POST User Manual Version 13.0
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POST User Manual Update Sheet for Version 13.0 November 2010 Modifications: The following modifications have been incorporated: Section
Page(s)
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POST User Manual
Contents TABLE OF CONTENTS
1.
Introduction ........................................................................................................ 1-1 1.1. General Description ................................................................................... 1-1 1.2. Facilities Available .................................................................................... 1-2 1.2.1. Shell Elements ................................................................................... 1-2 1.2.2. Laminated Shell Elements ................................................................. 1-3 1.2.3. Beam Elements .................................................................................. 1-3 1.2.4. Axisymmetric Solid and Shell Elements ........................................... 1-3 1.2.5. Harmonic Solids................................................................................. 1-3 1.3. Program Requirements............................................................................... 1-4 1.4. Element Grouping ...................................................................................... 1-4 1.5. Loadcase Combination............................................................................... 1-5 1.6. Local Axes Consideration .......................................................................... 1-5 1.6.1. Local Axes for SHELL, LAMI and SBEAM Data ............................ 1-5 1.6.2. Local Axis for BRICK Data .............................................................. 1-6 1.6.3. Output Axes Definition ...................................................................... 1-6 1.6.4. Averaging Groups with Differing Output Systems ......................... 1-13 1.6.5. Material Axes for Laminated Shells ................................................ 1-14 1.7. Processing of Summed Out-of-Plane Shear Forces for the TRB3 Element 115 1.8. Boundary Conditions for Harmonic Runs ............................................... 1-16 1.9. UNITS ...................................................................................................... 1-16 2. INPUT Data ....................................................................................................... 2-1 2.1. General Principles ...................................................................................... 2-1 2.1.1. Special Symbols ................................................................................. 2-3 2.2. UNITS Command ...................................................................................... 2-9 2.3. Data Type Commands.............................................................................. 2-11 2.3.1. Data Type and Sub-Type Commands .............................................. 2-11 2.4. Output Axis Commands........................................................................... 2-13 2.4.1. CONS Command (SHELL or SBEAM data) .................................. 2-13 2.4.2. OUTP Command (SHELL data only).............................................. 2-14 2.4.3. OUTR Command (SHELL data only) ............................................. 2-15 2.4.4. OUTT Command (SHELL data only) ............................................. 2-16 2.4.5. OUTB Command (SBEAM data only) ............................................ 2-16 2.4.6. SKEW Command (SHELL data only) ............................................. 2-17 2.5. Group Data Commands............................................................................ 2-18 2.5.1. LAYE Command (LAMI data only)................................................ 2-18 2.5.2. RDAT Command ............................................................................. 2-20 2.5.3. TCRD Command ............................................................................. 2-21 2.6. Group/Element Selection Commands ...................................................... 2-22 2.6.1. GROU Command............................................................................. 2-22 2.6.2. EXTR Command ............................................................................. 2-23 2.6.3. SKIP Command ............................................................................... 2-24 2.6.4. NOAV Command ............................................................................ 2-25 2.6.5. AVGR Command............................................................................. 2-26 2.7. Loadcase Combination Commands ......................................................... 2-27 2.7.1. NEWC Command ............................................................................ 2-27 2.7.2. ADDC Command............................................................................. 2-28
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2.7.3. ADDF Command ............................................................................. 2-29 2.8. Stress Type Selection Commands ............................................................ 2-31 2.8.1. FACT Command .............................................................................. 2-31 2.8.2. AVST Command ............................................................................. 2-31 2.8.3. FANM Command (SHELL data only) ............................................ 2-32 2.8.4. BANM Command (SHELL data only) ............................................ 2-33 2.8.5. PRST Command .............................................................................. 2-34 2.8.6. PRVM Command............................................................................. 2-35 2.8.7. SHRS Command (SHELL data only) .............................................. 2-36 2.8.8. WOOD Command (SHELL data only)............................................ 2-37 2.8.9. REIN Command (SHELL data only) ............................................... 2-38 2.9. Control Output Commands ...................................................................... 2-39 2.9.1. PRIN Command ............................................................................... 2-39 2.9.2. PLOT Command .............................................................................. 2-40 2.10. Check Stresses ......................................................................................... 2-41 2.10.1. FECS and FECM Commands (SHELL data only) .......................... 2-41 2.10.2. VONM Command ............................................................................ 2-42 2.10.3. TRES Command .............................................................................. 2-43 2.11. Harmonic Combination Commands ........................................................ 2-44 2.11.1. Data for Harmonic Analyses ............................................................ 2-44 2.11.2. ANGL Command (HARM Data only) ............................................ 2-45 2.11.3. COMB Command (HARM data only) ............................................. 2-45 2.11.4. SELE Command (HARM data only) ............................................... 2-46 2.11.5. COS and SIN Commands (HARM data only) ................................. 2-47 2.12. Miscellaneous Commands ....................................................................... 2-49 2.12.1. SECT Command .............................................................................. 2-49 2.12.2. ANGL Command (SHELL data only) ............................................. 2-50 2.12.3. END Command ................................................................................ 2-50 3. Examples ............................................................................................................ 3-1 3.1. Example 1: Default Data ........................................................................... 3-1 3.2. Example 2: Simple Shell Result Processing ............................................. 3-1 3.3. Example 3: Simple Axi-symmetric Result Processing ............................. 3-2 3.4. Example 4: Post Processing Component Results from Multi Level Axisymmetric Analysis .......................................................................................... 3-3 3.5. Example 5: Loadcase Combinations ......................................................... 3-4 3.6. Example 6: Post Processing Harmonic Analyses ..................................... 3-5 3.7. Example 7: Harmonic Combinations ........................................................ 3-6 3.8. Example 8: Post Processing Shell Compatible Beams ............................. 3-7 3.9. Example 9: Post Processing Laminated Shells ......................................... 3-8 4. Output ................................................................................................................ 4-1 4.1. Printed Output ............................................................................................ 4-1 4.1.1. SHELL Data....................................................................................... 4-1 4.1.2. LAMI Data ......................................................................................... 4-2 4.1.3. Shell BEAM Data .............................................................................. 4-2 4.1.4. BRICK, AXIS and HARM Data ........................................................ 4-2 4.2. Backing Files ............................................................................................. 4-2 4.3. Plotting Program Input ............................................................................... 4-3 4.3.1. FEMVIEW Input ............................................................................... 4-3 4.3.2. PATRAN® Input ................................................................................ 4-4 Appendix A - Preliminary Data Block for POST .................................................A-1
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A.1 Introduction ................................................................................................A-1 A.2 SYSTEM Command ..................................................................................A-2 A.3 PROJECT Command .................................................................................A-2 A.4 JOB Command ...........................................................................................A-3 A.5 FILES Command .......................................................................................A-3 A.6 TITLE Command .......................................................................................A-3 A.7 TEXT Command ........................................................................................A-4 A.8 STRUCTURE Command...........................................................................A-4 A.9 COMPONENT Command .........................................................................A-5 A.10 NEWSTRUCTURE Command .................................................................A-6 A.11 OPTIONS Command .................................................................................A-6 A.12 SAVE Command .......................................................................................A-8 A.13 RESU Command........................................................................................A-9 A.14 UNITS Command (not valid for fixed format ASAS data) .......................A-9 A.15 END Command ........................................................................................A-10 Appendix B - Running Instructions for POST .................................................. B-1 B.1 ASAS Files Required by POST ................................................................. B-1 B.2 Running Instructions for POST ................................................................. B-1 Appendix C - Equations used for Stress Calculations ....................................... C-1 C.1 Notation...................................................................................................... C-1 C.2 Stress Formulae .......................................................................................... C-2 C.3 Wood-Armer Calculations ......................................................................... C-3 C.3.1 Wood-Armer Moments - Orthogonal Reinforcing ............................ C-3 C.3.2 Wood-Armer Moments - Skewed Reinforcing .................................. C-4 C.4 Reinforcement Area Calculations .............................................................. C-4 Appendix D - - Loadcase Combination Methods ................................................D-1
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Introduction
POST Post-processing for ASAS Stress Output 1.
Introduction
1.1. General Description POST is a general post-processing program designed to aid the engineer using ASAS to analyse shell, solid and three-dimensional axisymmetric structures. It performs many tedious tasks on the ASAS results such that the engineer can concentrate on the design of his structure without the need to waste precious man time in repetitive arithmetic calculations. ASAS and LOCO finish by printing stresses and/or moments for each node of each element and storing these on a backing file. POST reads these stresses from the backing file and averages the stresses given by all the elements at each node. From these, surface, principal, von-Mises, Tresca, section stresses and Wood-Armer moments may be calculated and printed depending on the processing requested and the element type. These and other facilities are described fully in the next section. Note that if POST is to be run, the command SAVE LOCO FILES must be included in the preliminary data of the previous ASAS or LOCO run, so that the appropriate files will be retained for use by the program. The program will also convert stress results into a suitable format ready for plotting using FEMVIEW or PATRAN®*. To produce an interface file for one of these plotting programs, SAVE commands must be given in the POST preliminary data (see Appendix A-). In addition, the run results may be saved permanently on the project files using the RESU command. Note that the BR32 element is not available with FEMVIEW at present. *
PATRAN®
- a corporate trademark of the MSC Software Corporation.
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Introduction
1.2. Facilities Available POST has six different processing paths depending on which type of element is being considered. The process required is selected by the user and causes POST to processes only those elements of the correct type in the model. Thus an analysis having a number of differing element types will require more than one run of POST to post-process the whole model. The processes are identified by data type as follows: Data Type Command
Element Family
SHELL
thick & thin shells
Elements
QUS4 TCS6 TCS8 GCS6 GCS8 TBC3
plate membranes sandwiches triangular plate
SLB8 QUM4 QUM8 TRM3 TRM6 SND6 SND8 SN12 SND16 TRB3
LAMI
laminated shells
QUS4 TCS6 TCS8
SBEAM
shell compatible beams
BRICK
bricks
AXIS SOLID AXIS SHELL
axisymmetric solids axisymmetric shells
QUX4 QUX8 TRX3 TRX6 ASH2
HARM SOLID HARM SHELL
harmonic axisymmetric solids harmonic axisymmetric shells
QHX4 QHX8 THX3 THX6 AHH2
GCB3 TCBM BRK6 BRK8 BR15 BR20 BR32 TET4 TE10
Only one data type command may be submitted in each run; other data type commands will be ignored. Restriction: When using SAVE FEMS or SAVE PICA, only one of the shell element families may be processed in each run. The GROU command should be used to restrict the element type(s) to those associated with one of the SHELL families. (Note that thick and thin plates are considered as one element family).
1.2.1.
Shell Elements
For Shell elements, top, middle and bottom surface stresses are calculated for each element in turn, and a set of average stresses is calculated for each node which is associated with two or more elements. The outshears for plate and shell elements, with the exception of the TRB3 element, may also be averaged by using the SHRS command. The in-plane principal stresses ( stress difference (
1
-
2).
1
and
2)
are printed for each of the three surfaces along with the principal
Two ‟check stresses‟ can be provided by the user, against which the stresses at each
node can be compared and flagged if they exceed the check stress. As an aid to results interpretation, asterisks are used to highlight the highest absolute values of
1,
2 and
(
1
-
2)
for each surface.
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1.2.2.
Introduction
Laminated Shell Elements
The nodal stresses in and normal to the fibre direction and also the inshear stress are calculated for individual laminae from the resultant strain for the whole composite section. Where a node is associated with more than one element in the same group the strains for the whole composite section will be averaged at the node prior to the layer stresses being calculated.
1.2.3.
Beam Elements
Results for TCBM and GCB3 elements are processed in terms of member forces and moments. Where a node is associated with more than one element within the same groups the averaged results will be presented. The user may also specify a new output axes for the elements to override the default element local axes.
1.2.4.
Axisymmetric Solid and Shell Elements
The program calculates average nodal stresses for the solid elements. The user may print the averaged nodal stresses for any or all of the loadcases, each factored by a constant if required. In addition to the average nodal stresses the program prints the von Mises equivalent stress for each node and the factor by which this stress exceeds a user defined allowable level. The user may also request a printout of principal stresses and directions for any or all of the loadcases, again factored by a constant if required. In addition to the principal stresses and directions, the program prints the sum of the principal stresses, the von Mises equivalent stress, the Tresca stress and the factor by which the Tresca stress exceeds a user defined allowable level. For axisymmetric solids only, the user may request additional information for the stresses across a specified section of the structure. This comprises the average „membrane‟ stress components across the section and the bending stress components at each node across the section. The principal membrane stresses are also printed along with the corresponding stress intensities.
1.2.5.
Harmonic Solids
Additional features of POST permit the calculation of the average nodal stresses for the harmonic solid elements THX3, QHX4, THX6 and QHX8. The user may generate a number of combined loadcases from structures with different harmonic numbers (analogous to the manner of operation of LOCO) and produce stress output at a number of angular stations around the structure for these combined loadcases. This allows the user to perform Fourier series types of analysis for known harmonics of load at substantially less cost than would be involved in a full three dimensional (brick) analysis.
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Introduction
In order to identify the combined results being created, a new structure name is required and this is defined using the NEWSTRUCTURE command in the preliminary data. If the set of files for the combined loadcases has been saved and additional POST runs on the same load cases are needed, a harmonic re-run with simplified data input requirements may be performed. In the re-run, the structure name becomes the new structure name in the original run with the NEWSTRUCTURE command omitted. All the loadcase combination data are also omitted. Average nodal stresses at each circumferential station, von Mises equivalent stress and the factor by which it exceeds a user defined allowable are printed. Principal stresses may be produced in an analogous manner to the purely axisymmetric values described above. Currently the facility to produce extra information about stresses across specific sections is not available with the harmonic elements.
1.3. Program Requirements The program works directly from backing files created during an ASAS or LOCO run. The files described must be saved using the appropriate commands described in the User Manuals. All other information is provided via the data commands described in detail in Chapter 2 Any elements other than those allowed for the data type specified in Section 1.2 are ignored by the program; however, at least one of these elements types must be encountered. For an axisymmetric job all the elements are not only axisymmetric themselves but the loading is also axisymmetric. For harmonic analyses the program checks that the user specified harmonic number on all the harmonic elements accessed from an individual ASAS structure have the same harmonic number. Clearly, a structure with a mixed harmonics in a loadcase is physically meaningless as discontinuities in displacements are implied.
1.4. Element Grouping It may not always be desirable, or even meaningful, to average the nodal stresses of adjacent elements. For example, where there are different material properties or thicknesses between elements, the strains may be continuous but there will be step changes in the stresses.
If the nodal stresses are averaged at such
discontinuities, these step changes will be lost and a false average obtained. For this reason, POST considers the elements in groups. These groups may be made up of one ASAS element group (i.e. the groups defined in the ASAS element topology data), or of elements defined by a list of element numbers in the POST data. In the case of the former, individual elements may be omitted from a group by using the SKIP command in the POST data. Note that if EXTR groups are created in POST, then the CREATE Command should be used on the SAVE FEMS line. POST works through the groups in order, considering all loadcases for one group before moving on to the next. Within the groups, all nodal stresses are averaged, but no averaging occurs across the group boundaries.
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Introduction
If a group contains a mixture of more than one sub-type, e.g. shells, plates and membranes, then POST will only process elements with the same type as the first valid element found for that group (i.e. shell, membrane or plate). If other element types are required from a group then new groups can be created using the EXTR command (Section 2.6.2) containing only the element types required. In SHELL data, should any thickness discontinuity be encountered between adjacent elements within a group, an error message is printed and POST moves on to the next group. The allowable tolerance is 1% difference in thickness at each node. It is possible to override this error by a warning if option CCGO is specified in the preliminary data. For SHELL and SBEAM data, a check is also provided to ensure the offset compatibility between adjacent elements within a group. An error message is printed if this check fails and POST moves on to the next group. As before, it is possible to change the error status to warning status by specifying option CCGO in the preliminary data. For LAMI data, strains rather than stresses are averaged. Nodal thickness however, is used in the calculation of the individual lamina stresses and so once again there may not be nodal discontinuities within a group. Additionally all the elements within the group must have a consistent ASAS material axes and composite layer data in order that the layer stresses are calculated correctly from the averaged strains. Further consideration of the ASAS material orientation is given in Section 1.6.5.
1.5. Loadcase Combination The program allows the user to create new loadcases by factoring and combining any or all of the existing loadcases, including new loadcases already created. Average nodal stresses and principal stresses may be printed for these combinations as well as for the original loadcases. A number of combination methods are available in addition to simple summation. These are described in detail in Appendix D-.
1.6. Local Axes Consideration
1.6.1.
Local Axes for SHELL, LAMI and SBEAM Data
ASAS nodal stresses are calculated in the element local axis system for some shell elements and the shell beam elements. In cases where the element local axis systems of adjacent elements within an element group are not consistent (that is, the same orientation with respect to the global axis system), it is not meaningful to average nodal stresses across element boundaries. In such cases it is possible to reorientate the stresses into a consistent set before averaging by specifying a new axis system, called the output axis system, which is common to all elements within the group.
The new output axis systems are defined by the OUTP, OUTR, and OUTT
commands for shell elements and the OUTB command for the shell beam elements. Whilst an output command must be used for any group containing elements with inconsistent axes they may also be used whenever the user simply wants to reorientate the output axes. If an output command is not used for a
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Introduction
given group, then the CONS command should be used for that group, indicating the axes are consistent. POST is not able to check for axes consistency, so if CONS is used it is the user‟s responsibility to satisfy himself that the axes are consistent. For laminated shells the strains used to calculate the individual layer stresses are once again in the element‟s local axes system. In this case the output orientation of the results is already predefined by the fibre orientation for each layer which in turn is related to the material axes of each each element. POST automatically converts the ASAS strains into the material axes before the nodal averaging, and then further rotates the strains into the fibre direction for each of the individual layers examined.
1.6.2.
Local Axis for BRICK Data
In the case of brick and axi/harmonic elements, the ASAS results are in the global axis system and therefore consistent. For this reason there are no commands for reorientating stresses for these element types.
1.6.3. (a)
Output Axes Definition Cartesian Axes System - OUTP Command
The cartesian axes are defined in terms of a reference direction and a reference point. Firstly, the top and bottom surfaces of the shell are defined. This is done by drawing a vector from the reference point towards the node in question. This is called the control vector. The first surface cut by the control vector is defined as the bottom surface, and the second as the top surface. The new Z axis at this node is normal to the shell and positive in the direction from the bottom surface towards the top surface. See Figure 1. The new X axis lies in the plane containing the new Z axis and the reference direction: note that the reference direction is specified by direction cosines with respect to the global axis system. The X axis is positive on the side of the Z axis containing the positive reference direction. The new Y axis forms a right-handed set with the new X and Z axes. See Figure 2. The above rules break down in two cases. The first is where the reference direction and the new Z axis are parallel and the second where the control vector is tangential to the shell surface. In both cases, warnings are printed when the control vector is within 5 of the shell surface tangent. Errors are printed should the angle be less than 1 . In the case of an error the node in question is omitted.
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Figure 1
Introduction
Figure 2
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Example: Cylindrical Shells Consider a cylindrical shell of diameter 10 and length 100 orientated parallel to the Z axis with its central axis at X=5, Y=0. A suitable output axes may be specified by a reference direction parallel to the central axis and the reference point on the central axis halfway along the cylinder.
Figure 3 The reference point could be anywhere within the boundary of the tube, but the central location ensures the least chance of failing the 5º check. The resulting output axes system has the outer surface of the cylinder as the top surface, the local x‟ stress in the longitudinal direction and the local y‟ stress in the hoop direction.
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Example: Flat Shells/Plates For a flat plate the ideal position for the reference point is on the plate normal through the centre of the plate at a distance equivalent to half the plate length below the plate. Again the exact position is not critical. The reference direction should then be defined in the plane of the plate in the direction required for the local x‟ stress.
L 2
Figure 4 In some cases it may be desirable to use the same output axes definition for a series of plates. If the reference point is placed between plates this will result in a reversal of the local y‟ direction. This may not be significant for stress results but will affect the definition of the skew angles for Wood-Armer moments and reinforcement area calculations.
y'
x'
T B
Reference point
x' y'
B T
y'
x'
T B
y'
x'
T B
Reference point
Figure 5
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(b)
Introduction
Radial Axes System - OUTR Command
The cartesian axes definition cannot be used to give radial and hoop stresses for a flat circular disc. In order to cover this case the radial axes definition may be used. These axes are defined by two points, the first is the centre point for the radial axes system and the second is a reference point as for the cartesian axes system. A reference direction is set up for each individual node within the group and is defined by the vector from the node to the centre point. The local axes system for the node is then set up from the reference direction and the reference point using the same conventions as for cartesian axes definition. See Figure 6. At the centre of the disc the centre point may coincide with the central node, such that a reference direction is not defined. In this case (and also if the reference direction defined is normal to the shell) the local X will be defined as lying in the plane containing the local Z (or shell normal) and the global ordinate that is most normal to the local Z. In the case of the local Z being normal to two global ordinates, the global X would be used as first preference and the global Y as the second. The local Y is then defined normally to both local X and Z.
Reference Direction for Node 1
Figure 6
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Introduction
Example: Hemispherical Shell/Disc For a hemispherical shell the reference point should be placed at or near the centre of the hemisphere (at zero radius) and the centre point on the hemisphere at the centre. In the case of a flat disc the reference point should be positioned on the axis of the disc at a distance equivalent to the radius of the disc below the disc.
Figure 7 In both cases the local y‟ stress will be in the hoop direction. For the hemispherical shell the local x‟ stresses will be in the longitudinal direction and for the flat disc in the radial direction.
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(c)
Introduction
Toroidal Axes System - OUTT Command
The toroidal axes system is used to give hoop and longitudinal stresses for torus shaped structures. These axes are defined by the coordinates of the torus centre point, the direction cosines for the major axes and the major radius. For each node a radial slice is made through the torus at the position of the node. The axes reference point for the node is then defined as being on the circular minor axis at the position of the slice, and the reference direction as tangential to the circular minor axis at the same point. The reference direction is positive in the positive sense of the minor axes which itself follows a right hand screw rule with the direction cosines defining the major axes. The local axes system for the node is then set up form the reference direction and reference point using the same conventions as for the cartesian axes definition. See Figure 8. For the toroidal axes system, the major radius may not be zero (instead the OUTP or OUTR systems should be used). Also if the node under consideration lies on the circular minor axes, the local axes for the node cannot be defined and the elements containing this node will be skipped.
Figure 8 OUTT Axes System See Figure 10 for an example demonstrating the use of the OUTT output axes system.
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(d)
Introduction
Beam Axes System - OUTB Command
The new output axes system is assumed to have the X lying tangentially along the beam element. The positive direction is defined by specifying a reference direction for the output X-axis. The positive direction along the beam is that which gives an angle in the range of ±90 with the reference direction. A second reference direction (relating to the Z) is used to complete the output axes system. The new Y is positioned such that it is mutually perpendicular to the new X and the second reference direction, the direction forming a right handed set with the reference direction and the new X. Finally the new Z is positioned to form an orthogonal right handed axes set with the new X and Y. Example output systems for beam elements are shown in Figure 9.
Z Z Axis Reference Direction
X
Y X Axis Reference Direction Z
X
Y
Figure 9 OUTB Axes System
1.6.4.
Averaging Groups with Differing Output Systems
The AVGR command gives the user the ability to average across group boundaries with differing output axes systems. This is admissible, but the user must ensure that where the groups meet the local axes systems are aligned so that averaging is valid.
Figure 10 shows a typical example of where averaging across group
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Introduction
boundaries with differing output axes systems may be used. The structure consists of a cylinder (Group 1 with output system OUTP), connected to a 90 section of a pipe bend or torus (Group 2 with output system OUTT). The other end of the bend connects to a second cylinder (Group 3 with output system OUTP). Finally the second cylinder is closed with a spherical cap (Group 4 with output system OUTR). For each section, the longitudinal stress is
x
and the hoop stress is
y.
The through thickness direction for all Groups in the local Z
axis.
Figure 10 Example of Averaging Across Groups
1.6.5.
Material Axes for Laminated Shells
The consistency of the material axes is a requirement for POST since the element strains are converted into the material axes prior to combination. This is usually satisfied unless different global reference axes have been defined to set up the material axes on adjacent elements. Figure 11 shows the relationship between global axes, element local axes, material axes and fibre orientation. Layers are numbered from the bottom surface of the shell element (on the negative local Z side of the element) towards the top surface.
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Introduction
Figure 11
1.7. Processing of Summed Out-of-Plane Shear Forces for the TRB3 Element For the TRB3 elements only, the nodal shear value obtained using the FANM command is the sum of the nodal shear force from all elements surrounding the node. This value is of limited use as it represents the outforce balancing any external force or reaction at that node and gives little indication of the internal shearing force in the plate. More useful values are obtained if the nodal shears are summed either side of a line or section defined by the element boundaries. The section may form a closed loop ie, first and last nodes identical, or may be open ended. If the FANM/BANM/AVST and the SECT commands are present in the data, the normal output is augmented by an extra table. The summed nodal shears on each side of the section are reported for each nodal point on the section, giving two shear forces at each node. The elements which contribute to each value are also reported.
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Introduction
These shear forces may be interpreted to give a picture of the internal shearing forces at each node on the section.
1.8. Boundary Conditions for Harmonic Runs If the harmonic part of the program is used then each ASAS job accessed must have the same element topology data. Thus, if an analysis was to combine a purely axisymmetric structure (and load) this must be run as a harmonic job with the geometry property for the harmonic number set to 0.0. To restrain rigid body motions special suppression data are required for the harmonics 0 and 1. For harmonic 0 at least one TH ( ) degree of freedom should be removed, to prevent the structure rotating as a rigid body about the Z axis. For harmonic 1 there must be at least one R and one
degree of freedom suppressed as the displaced shape implied by this
harmonic corresponds to a rigid body motion of the section in the R– plane. All harmonics require at least one Z suppression, but for the harmonics 2 and above there is no need to have any R or
suppressions to remove
rigid body movements.
1.9. UNITS If UNITS have been employed in the ASAS analysis it is possible to specify modified units for both the POST input data and the results. The default units will be those utilised in the original analysis and if this is satisfactory then no additional information is required in the POST data. Note, however, that the angular data unit defaults to degrees. If modified units for input data are required, this is achieved by specifying one or more UNITS commands within the main body of the POST data thus permitting a combination of unit systems within the one data file (see Section 2.2 UNITS command). If the stress results are required in different units to the default, the UNITS command can be specified in the Preliminary data. See Appendix A-, Preliminary Data. If UNITS were not employed in the ASAS analysis, the units of all data supplied must be consistent with that adopted for the original data. No modification to reported stresses is possible under these circumstances.
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Introduction
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2.
Input Data
INPUT Data
As with most of the member programs of the ASAS suite, the input of information and data is divided into two sections. The first is the Preliminary Data and the second is the POST Data. The Preliminary Data defines the relationship of the run to all the other runs already completed in the project, the backing files required, and also specifies the title of the run. If subsequent processing is required after POST, the data to be saved from the run must also be defined in the Preliminary Data. The full details of these commands, along with examples, are given in Appendix A- of this manual. A summary of the POST commands available is given in Table 1. Detailed descriptions of each of the commands will be found in the remainder of Chapter 2
2.1. General Principles The input data for POST are specified according to syntax diagrams similar to the one shown below. The conventions adopted are described in the following paragraphs.
Within a data block, each horizontal branch represents a possible input instruction. Input instructions are composed of keywords (shown in upper-case), numerical values or alphanumerics (shown in lower-case characters), and special symbols. Each item in the list is separated from each other by a comma or one or more blank spaces. An input line must not be longer than 80 characters. Numerical values have to be given in one of two forms: (i)
If an integer is required a decimal point must not be supplied.
(ii)
If a real is required the decimal point may be omitted if the value is a whole number.
Exponent formats may be utilised when real numbers are required. For example
0.004
4.0E-3
4.0D-3
are equivalent
similarly
410.0
410
4.10E2
have the same value
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Input Data
The letters A-Z may be supplied in either upper or lower case but no distinction is made between the upper and lower case form. Hence “A” is assumed identical with “a”, “B” with “b” and so on. For example
COMB
are all identical strings
Comb comb Integer lists are terminated by supplying an END command either on the last line of the integer data, or on the line immediately after. For example GROU 1 5
is the same as 6
END
GROU 1 5 END
6
Note that END following immediately after the header line specifies no values. For example GROU END In order to reduce the amount of data required, facilities exist to abbreviate the integer lists. (i)
Where the integer list represents all items from an existing list (for example, choosing all groups for processing) the list may be replaced by the word ALL. GROU ALL Note that when ALL is utilised, the keyword END is omitted. This may not be used where the integer list is to specify new items of information, for example, new loadcase numbers.
(ii)
A sequence of integers may be generated by giving the first value and following this with the negative of the last value for example 5 -8 generates the numbers 5,6,7 and 8.
If a command is optional, this is shown by an arrow which bypasses the line(s)
HEADER list
END
A data list is indicated by a horizontal arrow around the list variable
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Input Data
list
Where one or more possible alternative items may appear in the line, these are shown be separate branches for each
KEYWORD1 KEYWORD2
2.1.1.
Special Symbols
The following is a list of characters which have a special significance to the LOCO input.
*
An asterisk is used to define the beginning of a comment, whatever follows on the line will not be interpreted. It may appear anywhere on the line, any preceding data will be processed as normal. For example * THIS IS A COMMENT FOR THE WHOLE LINE case 4 2.7 * THIS IS A COMMENT FOR PART OF A LINE
’
single quotes are used to enclose some text strings which could contain otherwise inadmissible characters. The quotes are placed at each end of the string. They may also be used to provide in-line comments between data items on a given line. For example STRUCTURE
,
’As used for design study’
STRU
A comma or one or more consecutive blanks will act as a delimiter between items in the line. For example
5, 10, 15
is the same as
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5
10
15
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Input Data
Note that two commas together signify that an item has been omitted. This may be permissible for certain data blocks. For example
5,, 15
is the same as
5
0
15
Unless otherwise stated in the section describing the data block, omitted numerical values are zero.
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Input Data
Table 1 : Summary of Commands
Units Command Command UNIT
Meaning Input units definition
Section 2.2 Additional Data Required
Unit name(s)
Valid For all
Data Type Commands Command
Meaning
1
Section 2.3 Additional Data Required
Valid For
SHELL
SHELL
None
S
LAMI
LAMI type data
None
L
SBEAM
Shell BEAM type data
None
Sb
BRICK
BRICK type data
None
B
AXIS
AXISYMMETRIC type data
Data sub-type (on new line)
A
HARM
HARMONIC type data
Data sub-type (on new line)
H
SOLID
Data sub-type - SOLID elements
None
AH
SHELL
Data sub-type - SHELL elements
None
AH
Output Axis Commands Command
Meaning
Note
Note
Section 2.4 Additional Data Required
Valid For
Note
CONS
Consistent local axis system throughout elements
None
Sb
2
OUTP
Define cartesian output axis system
6 real numbers = 3 direction cosines, 3 coordinates
S
2
OUTR
Define radial output axis system
6 real numbers = 2 sets of 3 coordinates
S
2
OUTT
Define toroidal output axis system
7 real numbers = 3 coordinates, 3 direction cosines, 1 radius
S
2
OUTB
Define beam output axis system
6 real numbers = 2 sets of direction cosines
Sb
SKEW
Defines (non orthogonal) x, y, directions for Wood-Armer and reinforcement area calculations
2 real angles (degrees)
S
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Input Data
Group Data Commands Command
Meaning
Section 2.5 Additional Data Required
Valid For
Note
LAYE
Define laminate layers to be processed
Integer list of lamina layers or ALL
L
RDAT
Define data required for tensile reinforcement area calculations
4 real numbers = 2 design stresses, 2 cover depths
S
3
TCRD
Define data required for tensile/compressive reinforcement area calculations
5 real numbers = 3 design stresses, 2 cover depths
S
3
Group/Element Selection Commands Command
Meaning
Additional Data Required
Section 2.6 Valid For
GROU
Selection of specified ASAS groups
Integer list of ASAS groups or ALL
all
EXTR
Selects extra groups of elements
Integer list of user element numbers
all
SKIP
Selects elements not to be considered
Integer list of element numbers
all
NOAV
Prevents stress averaging at nodes
None
all
AVGR
Amalgamates groups for stress averaging
Integer list of ASAS groups or ALL
all
Loadcase Combination Commands Command
Meaning
Additional Data Required
Section 2.7 Valid For
NEWC
Defines new loadcase numbers
Integer list of loadcase numbers
all
ADDC
Defines loadcases to be used in creating new loadcases
Integer list of ASAS loadcase numbers
all
ADDF
Defines loadcases with specific factors used in creating new loadcases
Integer loadcase number followed by integer-real pairs for loadcase number and factor
all
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Note
Note
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Input Data
Stress Type Selection Commands Command
Meaning
Additional Data Required
Section 2.8 Valid For
FACT
Defines a factor to be applied to results
One real factor
all
AVST
Selects loadcases for processing of averaged stresses
Integer list of loadcase numbers or ALL
all
FANM
Forces and Moments printout for average stresses
Integer list of loadcase numbers or ALL
S
BANM
Bending and membrane printout for average stresses
Integer list of loadcase numbers or ALL
S
PRST
Selects loadcases for processing of principal stresses
Integer list of loadcase numbers or ALL
S Sb BAH
PRVM
Selects loadcases for processing of von Mises stresses
Integer list of loadcase numbers or ALL
S
SHRS
Selects loadcases for processing of averaged out-of-plane shear forces
Integer list of loadcase numbers
S
WOOD
Selects loadcases for processing of Wood-Armer moments
Integer list of loadcase numbers or ALL
S
REIN
Selects loadcases for processing of reinforcement areas
Integer list of loadcase numbers or ALL
S
Control Output Commands Command
Meaning
Additional Data Required
4
Section 2.9 Valid For
PRIN
Selects loadcases for printing
Integer list of loadcase numbers or ALL
all
PLOT
Selects loadcases for plotting
Integer list of loadcase numbers or ALL
all
Check Stresses Commands Command
Meaning
Additional Data Required
Note
Section 2.10 Valid For
FECS
Defines surface stress allowable
One real stress value
S
FECM
Defines mid-plane stress allowable
One real stress value
S
VONM
Defines level of allowable von Mises stress
One real stress value
BAH
TRES
Defines level of allowable Tresca stress
One real stress value
BAH
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Note
Note
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Input Data
Harmonic Combination Commands Command
Meaning
Additional Data Required
Section 2.11 Valid For
Note
ANGL
Defines angular position around structure for stress output
List of angles
H
5
COMB
Defines number of new loadcases
One integer value
H
5
SELE
Define new loadcase numbers and titles
List of new loadcase numbers and titles
H
5
COS
Selects component loadcases and defines factors for combined cases (even expansion about =0 )
List of component loadcase numbers and factors
H
5
SIN
Selects component loadcases and defines factors for combined cases (odd expansion about =0 )
List of component loadcase numbers and factors
H
5
Miscellaneous Commands Command
Section 2.12
Meaning
Additional Data Required
SECT
Defines a section across which stresses are to be calculated
Integer list of ASAS group numbers, section numbers and node numbers
AS
ANGL
To print the angle of the principal axes for SHELL type data or define angular location for HARM type data
None for SHELL type data. Real list of angular locations for HARM type data
SH
NAME
For PATRAN, instructs POST to create stress files using the first four characters of the name followed by a unique integer and extension, e.g. MODE0001.NOD MODE0002.NOD etc
Name of model to be created in PATRAN database e.g. MODE
all
VMPS
This command defines that von Mises stress is to be calculated from principal stresses. If no VMPS command is present the von Mises stress is calculated from average stresses. Not applicable for PATRAN.
SB AH
END
Terminate the run
all
Data types:
S
-
Shell type data
Sb -
Shell beam type data
L
-
Laminated shell type data
B
-
Brick type data
A
-
Axisymmetric type data
H
-
Harmonic type data
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Valid For
Note
6
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Input Data
Notes 1.
UNIT command may only be used if units have been specified in the preceding ASAS run.
2.
Only one is applicable to a group of elements, however different groups may have different output axis within the same run. If none are present then CONS is assumed.
3.
RDAT and TCRD may be used in same run but must apply to different groups.
4.
For shell elements von-Mises stresses are not printed but the PRVM command will cause them to be added to the plot file.
5.
For HARM type jobs, these commands must follow the data sub-type command.
6.
Mandatory END command: all other decks are optional subject to note 2
2.2. UNITS Command Specifies the units associated with subsequent data. This command is only valid if UNITS were employed in the ASAS analysis (see Section 1.9).
UNITS
unit
Parameters UNITS
: keyword
unit
: name of unit to be utilised (see below)
Note Force, length and angular unit may be specified. Only those terms which are required to be modified need to be specified, undefined terms will default to those of the analysis global units unless previously overwritten by another UNITS command. The default angular unit is degrees for all data types. Valid unit names are as follows: Length
Force unit
METRE(S)
M
CENTIMETRE(S)
CM
MILLIMETRE(S)
MM
FOOT,FEET
FT
INCH,INCHES
IN
NEWTON(S)
N
KILONEWTON(S)
KN
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Angular unit
Input Data
MEGANEWTON(S)
MN
TONNEFORCE(S)
TNEF
POUNDAL(S)
PDL
POUNDFORCE
LBF
KIP(S)
KIP
TONFORCE(S)
TONF
KGFORCE(S)
KGF
RADIAN(S)
RAD(S)
DEGREES(S)
DEG(S)
The UNITS command may be repeated throughout the data deck thus permitting the greatest flexibility in the data input.
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Input Data
Example
Command
Operational Units
Notes
SYSTEM DATA AREA 50000 .
UNITS do not have to
. .
appear in the Preliminary data, see Section 1.9
UNITS N M .
NEWTON, METRES, DEGREES
and Appendix A-.
NEWTONS, METRES, DEGREES
Default global analysis units except that angular
. . END SHELL CONS GROU ALL
input is in degrees
AVST ALL UNIT MM
NEWTONS, MILLIMETRES, DEGREES
Stress now input in N/mm2
FECS 200.0 END
2.3. Data Type Commands
2.3.1.
Data Type and Sub-Type Commands
This command defines the type of elements to be processed in the POST run and must be the first command to follow the preliminary data.
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Input Data
SHELL LAMI SBEAM BRICK
SOLID AXIS SHELL SOLID HARM SHELL
Parameters SHELL
: keyword to denote that one or more of the following element types are to be processed: Shell Plate
GCS6, GCS8, TCS6, TCS8, TBC3, QUS4 SLB8, TRB3
Membrane Sandwich
QUM8, QUM4, TRM6, TRM3 SND6, SND8, SND12, SND16
Only one element type will be processed for each group defined (see Section 1.4) LAMI
: keyword to denote that laminated shells are to be processed: QUS4, TCS6 and TCS8 elements
SBEAM
: keyword to denote that shell beam elements are to be processed: TCBM or GCB3 elements
BRICK
: keyword to denote that brick elements are to be processed: BRK6, BRK8, BR20, BR32, TET4, TE10 elements
AXIS
: keyword to denote that the axisymmetric elements are to be processed SOLID : subcommand to AXIS to denote that axisymmetric solid elements are to be processed: TRX3, TRX6, QUX4, QUX8 elements SHELL : subcommand to AXIS to denote that the axisymmetric shell element is to be processed: ASH2 elements If neither subcommand is given, SOLID is assumed.
HARM
: keyword to denote that the axisymmetric harmonic elements are to be processed.
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SOLID
Input Data
:
subcommand to HARM to denote that harmonic solid elements are to be
processed: SHELL
:
THX3, THX6, QHX4, QHX8 elements
subcommand to HARM to denote that the harmonic shell element is to be
processed:
AHH2 elements
If neither subcommand is given, SOLID is assumed. Note All POST runs require either SHELL, LAMI, SBEAM, BRICK, AXIS or HARM as the first command following the preliminary data; they are mutually exclusive options.
2.4. Output Axis Commands
2.4.1.
CONS Command (SHELL or SBEAM data)
Specifies that the element local axis systems are consistent and that no stress reorientation is required (see Section 1.6)
CONS
Parameters CONS
: keyword
When CONS is specified, any groups referenced by subsequent GROU and EXTR group commands will be assumed to have consistent local element axis systems until a new output axis system is defined (OUTP, OUTR, OUTT, OUTB). If no output command is supplied, CONS will be assumed. Notes 1.
A group may only be assigned one axis system within the same run. Different groups however, may have different output axis systems.
2.
This command does not make elements within a group have consistent axes. If they do not already have consistent axes in the ASAS model then the CONS command must not be used otherwise invalid stress averaging will occur. In this instance one of the alternative output commands (OUTP, OUTR, OUTT, OUTB) must be used.
Example
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Input Data
CONS GROU 1 5 EXTR
END
10
16
2.4.2.
15
17
END
OUTP Command (SHELL data only)
Defines a cartesian/cylindrical output axis system into which all nodal stresses are to be converted prior to nodal averaging (see Section 1.6)
OUTP
dx
dy
dz
x
y
z
Parameters OUTP
: keyword
dx,dy,dz : direction cosines of the reference direction with respect to the global axis system. (Real) x,y,z
: global coordinates of the reference point. (Real)
When OUTP is specified, any groups referenced by subsequent GROU and EXTR group commands will adopt the output axis system defined by the direction cosines and reference point until a new output axis system is defined (CONS, OUTR, OUTT, OUTP). Note A group may only be assigned one axis system within the same run. Different groups, however, may have different output axis systems. Example OUTP 0.7071
0.7071
0.0
10.0
0.0
0.0
GROU 1
5
END
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EXTRA 10 15
2.4.3.
16
Input Data
17
END
OUTR Command (SHELL data only)
Defines a radial/spherical output axes system into which all nodal stresses are to be converted prior to nodal averaging (see Section 1.6).
OUTR
xo
yo
zo
xr
yr
zr
Parameters OUTR
: keyword
xo,yo,zo : global coordinates of the centre point. (Real) xr,yr,zr
: global coordinates of the reference point. (Real)
When OUTR is specified, any groups referenced by subsequent GROU and EXTR group commands will adopt the output axis system defined by the two pairs of coordinates until a new output axis system is defined (CONS, OUTP, OUTT, OUTR). Note A group may only be assigned one axis system within the same run. Different groups, however, may have different output axis systems. Example OUTR 1.0 GROU
0.0
1 5 EXTRA 10
10.0
1.0
0.0
2.0
END 15
16
17
END
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2.4.4.
Input Data
OUTT Command (SHELL data only)
Defines a toroidal output axes system into which all nodal stresses are to be converted prior to nodal averaging (see Section 1.6).
OUTT
xc
yc
zc
dx
dy
dz
r
Parameters OUTT
: keyword
xc,yc,zc : global coordinates of centre of torus (Real) dx,dy,dz : direction cosines of major axis (Real) r
: major radius (Real)
When OUTT is specified, any groups referenced by subsequent GROU and EXTR group commands will adopt the output axis system defined by the specified torus until a new output axis system is defined (CONS, OUTR, OUTT, OUTP). Note A group may only be assigned one axis system within the same run. Different groups, however, may have different output axis systems. Example OUTT 100.00
0.0
100.0
0.0
1.0
0.0
25.0
GROUP
2.4.5.
OUTB Command (SBEAM data only)
Specifies information to determine output axis system for shell beam elements (see Section 1.6)
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Input Data
OUTB
dxx
dxy
dxz
dzx
dzy
dzz
Parameters OUTB
: keyword
dxx,dxy,dxz : directions cosines for x-axis reference direction with respect to the global axis system. (Real) dzx,dzy,dzz : direction cosines for z-axis reference direction with respect to the global axis system. (Real) When OUTB is specified, any groups referenced by subsequent GROU and EXTR group commands will adopt the output axis system defined by these direction cosines until a new output axis system is defined (CONS, OUTB). Note A group may only be assigned one axis system within the same run. Different groups, however, may have different output axis systems. Example OUTB 0.7071 GROU 7 5 EXTRA 10
2.4.6.
0.7071
0.0
0.0
0.0
1.0
END 15
16
17
END
SKEW Command (SHELL data only)
Defines the local axes for Wood-Armer moment and reinforcement area calculations.
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Input Data
SKEW
angx
angy
Parameters SKEW
: keyword
angx
: angle that local x axis makes to the output x axis (CONS, OUTP, OUTR or OUTT) (Real)
angy
: angle between local y axis and local x axis. (Real).
Notes 1.
The WOOD/REIN commands normally assume that orthogonal axes are in use. The SKEW command allows non-orthogonal axes to be defined.
2.
The angles defined are measured in a conventional right-handed system. The units are degrees.
Example SKEW 22.5
78.5
2.5. Group Data Commands
2.5.1.
LAYE Command (LAMI data only)
Specifies which layers of a laminated shell are to be processed.
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Input Data
LAYE
ilay
END
ALL
Parameters LAYE
: keyword
ilay
: individual layers to be processed
END
: keyword to denote the end of the current block of layer data. If the list of layers continues onto subsequent lines, END is required on the last line only.
ALL
: keyword to denote that all layers are to be reported. END not required.
Note When LAYE is specified, any groups referenced by subsequent GROU and EXTR group commands will have the layers processed that are defined on this command. If no LAYE command is given then all layers of the groups selected will be processed. Example LAYE 1 2 5 6 END GROU 1 2 END LAYE ALL EXTR 11 1 -20 END
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2.5.2.
Input Data
RDAT Command
Specifies details of allowable stresses and cover depths for tensile (only) reinforcement calculations. For this case it is assumed that all compressive stress is carried by the matrix (e.g. concrete) alone and all the tensile stress by the reinforcement (e.g. steel) alone.
RDAT
rdstrs
mdstrs
cdeps
Parameters RDAT
: keyword
rdstrs
: reinforcement design stress (Real)
mdstrs
: matrix design stress (Real)
cdeps
: cover depths (Real)
Notes 1.
If cdeps is omitted the cover depth for all reinforcing will default to 10% of the shell thickness.
2.
If only one cdeps value is specified, this is taken as the cover depth for all reinforcing.
3.
If two cdeps values are specified, these are taken as the top and bottom surface cover depths respectively.
4.
If four cdeps values are specified, these are taken as the top X and Y direction cover depths followed by the bottom X and Y direction cover depths.
5.
This data applies to any groups of elements defined on subsequent GROU or EXTR commands, until superceded by further RDAT or TCRD commands.
6.
RDAT and TCRD may appear in the same run but may not be for the same group of elements.
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2.5.3.
Input Data
TCRD Command
Specifies details of allowable stresses and cover depths for tensile/compressive reinforcement calculations. For this case it is assumed that the tensile stress is carried by the reinforcement (e.g. steel) alone, but the compressive stress is carried by both the matrix (e.g. concrete) and the reinforcement.
TCRD
rdtstr
rdcstr
mdstrs
cdeps
Parameters RDAT
: keyword
rdtstr
: tensile reinforcement design stress (Real)
rdcstr
: compressive reinforcement design stress (Real)
mdstrs
: matrix design stress (Real)
cdeps
: cover depths (Real)
Notes 1.
If cdeps is omitted the cover depth for all reinforcing will default to 10% of the shell thickness.
2.
If only one cdeps value is specified, this is taken as the cover depth for all reinforcing.
3.
If two cdeps values are specified, these are taken as the top and bottom surface cover depths respectively.
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Input Data
4.
If four cdeps values are specified, these are taken as the top X and Y direction cover depths followed by the bottom X and Y direction cover depths.
5.
This data applies to any groups of elements defined on subsequent GROU or EXTR commands, until superseded by further RDAT or TCRD commands.
6.
RDAT and TCRD may appear in the same run but may not be for the same group of elements.
2.6. Group/Element Selection Commands
2.6.1.
GROU Command
Specifies the ASAS group numbers to be processed by subsequent execution commands (AVST, PRST, SHRS, WOOD and REIN)
GROU igroup
END
ALL
Parameters GROU
: keyword
igroup
: ASAS group number to be processed (Integer). All the group numbers specified must exist otherwise POST will stop after data checking.
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END
Input Data
: keyword to denote the end of the current block of group number data. If the list of group numbers continues onto subsequent lines, END is required on last line only.
ALL
: keyword to indicate that all groups are selected. END is not required.
Note If this command is omitted, and provided no extra groups are specified (see Section 2.6.2, EXTR groups) then all the ASAS groups will be processed by default. If this command is omitted, but extra groups are defined, then none of the ASAS groups will be processed. Examples (i)
To process ASAS groups 1 2 3 4 GROU 1
(ii)
-4
END
To process all ASAS groups GROU ALL
(iii)
To process ASAS groups 1,3,5,7,10,12,14 GROU 1 10
2.6.2.
3 12
5
7 14
END
EXTR Command
Defines new group numbers and assigns elements to the groups for processing by subsequent execution commands (AVST, PRST, SHRS, WOOD and REIN)
EXTR
igroup
ielem
END
Parameters
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EXTR
: keyword
igroup
: group number for new group to be generated (Integer). This group number must be unique and must not exist in the original ASAS analysis.
ielem
: user element numbers to be included in the new group (Integer).
END
: keyword to denote the end of the current block of extra group data. If the list of element numbers continues onto subsequent lines, END is required on last line only.
Note 1.
One extra group is defined by each EXTR group command. Up to 50 groups may be processed at a time.
2.
This command effectively removes the elements from their original ASAS group since an element may only be in one group at a time.
3.
EXTR groups may be redefined with different lists of elements in separate runs of POST provided the Interface file is not saved from run to run.
4.
Note that if EXTR groups are created in POST, then the CREATE Command should be used on the SAVE FEMS line.
Examples (i)
New group 12 contains elements 7 to 35 EXTR 12
(ii)
7
-35
END
New group 5 contains elements 1 to 10 and new group 7 contains elements 11 to 20 EXTR 5 1
-10
END
EXTR 7
2.6.3.
11
12
13
14
15
-20
END
SKIP Command
Specifies user element numbers which are to be excluded from the analysis.
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SKIP
ielem
END
Parameters SKIP
: keyword
ielem
: user element number to be skipped (Integer)
END
: keyword to denote the end of the SKIP data. If the list of element numbers continues onto subsequent lines, END is required on last line only.
Note 1.
This command is used to remove elements from an ASAS group. If the skipped elements need processing on their own, the EXTR group command should be used which will remove the elements in the extra group from their original ASAS groups.
2.
Up to 500 elements may be skipped.
Example SKIP 1
2.6.4.
7
9
END
NOAV Command
Specifies that no averaging of adjacent element stresses is to be carried out.
NOAV
Parameters
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NOAV
Input Data
: keyword
Notes 1.
By default, nodal stresses of adjacent elements within a group are averaged and reported. For model checking it may be useful to manually check the absolute variation from element to element in a consistent axis set using this command together with an output axis system definition. (OUTP, OUTR, OUTT).
2.
With the NOAV command no thickness checks are carried out to ensure that all elements at a node have the same thickness.
3.
This command will require a significantly larger data area (see Appendix A.2) and will produce larger results files than usual and thus should be used with care.
2.6.5.
AVGR Command
Specifies a set of group numbers which are to be considered as one single group for the purposes of stress averaging.
AVGR igroup
END
ALL
Parameters AVGR
: keyword
igroup
: group number (Integer). This may be either an ASAS group or one defined in an earlier EXTR group command.
END
: keyword to denote the end of the current block of averaged group data. If the list of group numbers continues onto subsequent lines, END is required on last line only.
ALL
: keyword to indicate that all groups are selected. END is not required.
Notes 1.
By default, stress averaging only occurs between elements which are in the same group. (See Section 1.4). There may be situations, however, where groups of elements require different axis sets but stress averaging across the group boundaries is both desirable and meaningful (see Figure 10). This may be
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Input Data
achieved by use of the output axis commands (CONS, OUTP, OUTR, OUTT) and AVGR (See Section 1.6.4). 2.
The results will be reported under the first group number appearing in the list.
Example (see Figure 10) OUTP 0.0 0.0 1.0 0.0 0.0 50.0 GROUP 1 END OUTT 50.0 0.0 100.0 0.0 1.0 0.0 50.0 GROUP 2 END OUTP 1.0 0.0 0.0 100.0 0.0 150.0 GROUP 3 END OUTR 200.0 0.0 150.0 150.0 0.0 200.0 GROUP 4 END AVGR 1 2 3 4 END
2.7. Loadcase Combination Commands
2.7.1.
NEWC Command
Specifies the numbers and titles of new loadcases that are to be created using the ADDC and ADDF commands (see Sections 2.7.2 and 2.7.3 respectively).
NEWC
new case
END
loadcase
`title'
Parameters NEWC
: keyword
newcase : number of new loadcases to be created (Integer).
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END
Input Data
: keyword to denote the end of the current block of new loadcase numbers.
If the list of new
loadcase numbers continues onto subsequent lines, END is required on last line only. For each loadcase defined by newcase loadcase : loadcase number which must also appear in the newcase list above. (Integer) title
: title associated with the new loadcase number. (Maximum 40 characters)
Note The order of the title lines is not important. Example NEWC 5 5
7
9
11
END ’FIRST COMBINATION’
9 7
’THIRD COMBINATION’ ’SECOND COMBINATION’
11
’LAST COMBINATION’
2.7.2.
ADDC Command
Specifies the constituent loadcases to be added together to form a new loadcase defined in the NEWC command (see Section 2.7.1).
ADDC
new case
(keyw rd)
loadcase
END
Parameters ADDC
: keyword
keywrd
: second keyword to define the type of summation to be carried out to the constituent loadcases defined on the following line(s). Valid options are: SSUM
simple summation (default)
MAXE
maximum envelope
MINE
minimum envelope
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MXAE
maximum absolute envelope
ABSS
absolute sum
SRSS
square root sum square
REEN
reinforcement calculation envelope
WDME
Wood-Armer moment envelope
newcase : new loadcase number which must have been defined using the NEWC command. (Integer). loadcase : existing loadcase number to be used in the creation of the new loadcase (see notes below). (Integer) END
: keyword to denote the end of the current block of constituent data. If the list of loadcase numbers continues onto subsequent lines, END is required on last line only.
Notes 1.
The constituent loadcases are factored by the value defined in the latest FACT command.
2.
Either ADDC and/or ADDF commands must be used for each of the new loadcases defined on the NEWC command.
3.
The loadcase list may include new loadcases defined on earlier ADDC or ADDF commands.
4.
Appendix D- gives details of summation types.
Example ADDC 5
2.7.3.
SSUM 2
-4
END
ADDF Command
Specifies the constituent loadcases, together with their factors, to be added together to form a new loadcase defined in the NEWC command (see Section 2.7.1).
ADDF new case
(keyw rd) loadcase
factor
END
Parameters ADDF
: keyword
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keywrd
Input Data
: second keyword to define the type of summation to be carried out to the constituent loadcases defined on the following line(s). Valid options are: SSUM
simple summation (default)
MAXE
maximum envelope
MINE
minimum envelope
MXAE
maximum absolute envelope
ABSS
absolute sum
SRSS
square root sum square
MXLS
maximum limit stress
MNLS
minimum limit stress
WDME
Wood-Armer moment envelope
REEN
reinforcement calculation envelope
newcase : new loadcase number which must have been defined using the NEWC command. (Integer) loadcase : existing loadcase number to be used in the creation of the new loadcase (see notes below). (Integer) factor
: factor to be applied to the loadcase. (Real) For the MXLS and MNLS two factors per loadcase are required.
END
: keyword to denote the end of the current block of constituent data. If the list of loadcase numbers continues onto subsequent lines, END is required on the last line only.
Notes 1.
Either ADDC and/or ADDF commands must be used for each of the new loadcases defined as the NEWC command.
2.
The use of „-‟ to indicate a range of integers is prohibited in this command.
3.
The loadcase list may include new loadcases defined on earlier ADDC or ADDF commands.
4.
Appendix D- gives details of summation types.
Example ADDF 7 1
SSUM 1.5 2
ADDF MXLS 11 1 1.5
0.5 1.0
END 2
0.5
0.0
END
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2.8. Stress Type Selection Commands
2.8.1.
FACT Command
Specifies a factor to be applied to the stresses from the loadcases defined by subsequent execution commands (AVST, PRST, SHRS, WOOD and REIN) or loadcases referred to with the ADDC command. FACT factor
Parameters FACT
: keyword
factor
: scaling factor to be applied to subsequent loadcases. (Real)
Note The factor remains on the selected loadcases until it is overwritten by another FACT command. The default value is 1.0 Example FACT 105.0
2.8.2.
AVST Command
Specifies the loadcases for which average stresses are to be calculated.
AVST loadcase
END
ALL
Parameters
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AVST
Input Data
: keyword
loadcase : loadcase number to be processed (Integer). This must either appear in the original ASAS analysis or be defined in a NEWC command. END
: keyword to denote the end of the current block of averaged stress data. If the list of loadcase numbers continues onto subsequent lines, END is required on last line only.
ALL
: keyword to indicate that all loadcases are selected.
Notes 1.
If AVST and PRST commands are both omitted then the averaged stresses and principal stresses (if applicable) will be calculated for all loadcases in the ASAS run.
2.
For BRICK, AXIS and HARM data types, the von Mises equivalent stress is calculated during printing of average nodal stresses. The formulae are given in Appendix C-. If the von-Mises equivalent stress exceeds the allowable value set by a previous VONM command (see Section 2.10.2) the factor by which the allowable value is exceeded is also printed.
Example AVST 1 4
(i)
END
AVST ALL
(ii)
2.8.3.
6
FANM Command (SHELL data only)
Specifies the loadcases for average stress calculation where FORCES and MOMENTS are required, as opposed to surface stresses.
FANM loadcase
END
ALL
Parameters
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FANM
Input Data
: keyword
loadcase : loadcase number to be processed. (Integer). This must either appear in the original ASAS analysis or be defined in a NEWC command. END
: keyword to denote the end of the current block of force and moment data. If the list of loadcase numbers continues onto subsequent lines, END is required on the last line only.
ALL
: keyword to indicate that all loadcases are selected. END is not required.
Notes 1.
If FANM is specified, the nodal averaged values are output as force/unit length and moment/unit length instead of stresses at the top, middle and bottom surfaces.
2.
For TRB3 elements this command will produce summed through thickness shears for each node.
3.
FANM only controls the type of values output. AVST is also needed if nodal averaged values are required.
Example FANM 1
2.8.4.
3
END
BANM Command (SHELL data only)
Specifies the loadcases for average stress calculation where BENDING and MEMBRANE stresses are required, as opposed to surface stresses.
BANM
loadcase
END
ALL
Parameters BANM
: keyword
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Input Data
loadcase : loadcase number to be processed (Integer). This must either appear in the original ASAS analysis or be defined in a NEWC command. END
: keyword to denote the end of the current block of bending and membrane stress data. If the list of loadcase numbers continues onto subsequent lines, END is required on the last line only.
ALL
: keyword to indicate that all loadcases are selected. END is not required.
Note 1.
If BANM is specified, the nodal averaged values are output in the form of bending and membrane stresses instead of stresses at the top, middle and bottom surfaces.
2.
BANM only controls the type of values output. AVST is also needed if odal averaged values are required.
Example BANM 4
2.8.5.
-6
END
PRST Command
Specifies the loadcases for which principal stresses are to be calculated.
PRST loadcase
END
ALL
Parameters PRST
: keyword
loadcase : loadcase number to be processed. (Integer). This must either appear in the original ASAS analysis or be defined in a NEWC command. END
: keyword to denote the end of the current block of principal stress data. If the list of loadcase numbers continues onto subsequent lines, END is required on last line only.
ALL
: keyword to indicate that all loadcases are selected. END is not required.
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Notes 1.
If AVST and PRST commands are both omitted then the averaged stresses and principal stresses will be calculated for all loadcases in the ASAS run.
2.
During the processing of principal stresses for solid elements (including axi-symmetric) the Tresca stress and von Mises equivalent stress are calculated. The formulae are given in Appendix C-.
3.
For SHELL data, P3 is the through thickness stress and is equal to zero, and hence the Tresca stress becomes the greater of the P1, P2 or P1 - P2 values. This value of Tresca stress is flagged with an asterisk in the printout but not printed separately.
4.
The von-Mises equivalent stress is not printed but if the PRVM command is specified, the value is written to the plot file. See Section 2.8.6 and A.12.
5.
PRST may not be used with the SBEAM data type.
Example PRST 5 2
1
END
PRST ALL
2.8.6.
PRVM Command
Specifies the loadcases for which von-Mises equivalent stresses are to be processed.
PRVM
loadcase
END
ALL
Parameters PRVM
: keyword
loadcase
: loadcase number to be processed (Integer). This must either appear in the original ASAS analysis or be defined in a NEWC command.
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END
Input Data
: keyword to denote the end of the current block of von-Mises data. If the loadcase numbers continue onto subsequent lines, END is required on the last line only.
ALL
: keyword to indicate that all loadcases are selected. END is not required.
Notes 1.
This command must be used in conjunction with the PRST command, see section 2.8.5.
2.
The von-Mises stress is not printed for shell elements even when the PRVM command is used.
3.
The PRVM command causes the von-Mises stresses to be written to the plot file.
4.
The formulae used to calculate the von-Mises stress are given in Appendix C-.
Example PRVM 3
2.8.7.
7
9
END
SHRS Command (SHELL data only)
Specifies the loadcases for which average out of plane shear force/unit lengths are to be calculated.
SHRS
loadcase
END
ALL
Parameters SHRS
: keyword
loadcase
: loadcase number to be processed (Integer). This must either appear in the original ASAS analysis or be defined in a NEWC command.
END
: keyword to denote the end of the current block of SHRS data. If the loadcase numbers continue onto subsequent lines, END is required on the last line only.
ALL
: keyword to indicate that all loadcases are selected. END is not required.
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Notes 1.
This command should not be used for TRB3 elements which are covered separately by the SECT command in Section 2.12.1 (see also Section 1.7)
2.
SHRS only controls the type of values output. AVST is also needed if nodal averaged values are required.
Example SHRS 3
2.8.8.
7
9
END
WOOD Command (SHELL data only)
Specifies the loadcase numbers for which Wood-Armer moments are to be calculated. Only valid for SHELL data and element types GCS6, GCS8, TCS6, TCS8, TBC3, QUS4, SLB8 and TRB3.
WOOD
loadcase
END
ALL
Parameters WOOD
: keyword
loadcase : loadcase numbers to be processed (Integer). This must either appear in the original ASAS analysis or be defined in a NEWC command. END
: keyword to denote the end of the current list of loadcases. If the list of loadcase numbers continues onto subsequent lines, END is required on the last line only.
ALL
: keyword to indicate that all loadcases are selected. END is not required.
Notes 1.
The formulae used for calculating Wood-Armer moments are given in Appendix C-.
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2.
If Wood-Armer moment envelopes are required, the WDME combination type should be used on an ADDC/ADDF command (see Section 2.7.2/2.7.3).
3.
Specifying WOOD for a loadcase will automatically invoke the FANM command, unless BANM has been specified, in which case Wood-Armer stresses are produced.
Example WOOD 5
2.8.9.
3
END
REIN Command (SHELL data only)
Specifies the loadcase numbers for which reinforcement areas are to be calculated. Only valid for SHELL data and element types GCS6, GCS8, TCS6, TCS8, TBC3, QUS4, SLB8 and TRB3.
REIN
loadcase
END
ALL
Parameters REIN
: keyword
loadcase : loadcase numbers to be processed (Integer). This must either appear in the original ASAS analysis or be defined in a NEWC command. END
: keyword to denote the end of the current list of loadcases. If the list of loadcase numbers continues onto subsequent lines, END is required on the last line only.
ALL
: keyword to indicate that all loadcases are selected. END is not required.
Notes 1.
The formulae used for calculating Reinforcement Areas are given in Appendix C-.
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2.
If reinforcement area envelopes are required, the REEN combination type should be used on an ADDC/ADDF command (see Section 2.7.2/2.7.3).
3.
Specifying REIN for a loadcase will automatically invoke the FANM command.
Example REIN 5
3
END
2.9. Control Output Commands
2.9.1.
PRIN Command
Specifies which loadcases are to be printed. Only loadcases that are processed may be printed (AVST, PRST, SHRS, WOOD and REIN commands).
PRIN loadcase
END
ALL
Parameters PRIN
: Keyword
loadcase : loadcase number to be printed. (Integer) END
: keyword to denote the end of the current block of print data. If the list of loadcase numbers continues onto subsequent lines, END is required on the last line only.
ALL
: keyword to indicate all loadcases are selected. END is not required.
Notes 1.
By default all loadcases that are processed will be printed.
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2.
Input Data
The PRIN command must only be used with a SAVE plot FILE command (see Appendix A.12). In this case, all cases processed will be written to the plot file.
Example To print loadcases 5 and 6 only PRIN 5
6
END
To suppress printing of all the loadcases PRIN END
2.9.2.
PLOT Command
Used to specify which loadcases are to be saved for processing with any valid plotting program. Only loadcases that are processed may be plotted (AVST, PRST, SHRS, WOOD and REIN commands). A SAVE plot FILE command must be supplied in the preliminary data if plotting is required (see section A.12).
PLOT loadcase
END
ALL
Parameters PLOT
: keyword
loadcase : loadcase number to be saved for plotting. (Integer) END
: keyword to denote the end of the PLOT data. If the list of loadcase numbers continue onto subsequent lines, END is required on the last line only.
ALL
: keyword to indicate that all loadcases are selected. END is not required.
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Notes 1.
If the PLOT command is omitted then all loadcases that are processed will be saved for plotting if a SAVE plot FILE command has been supplied, otherwise none is saved.
2.
If the PLOT command is used and no SAVE plot FILE command has been specified, the program will terminate after reading the data.
Example Cases 1,2,3,6,7 and 8 will be added to the plot file. PLOT 1
2
3
6
-8
END
All loadcases processed will be added to the plot file. PLOT ALL No results will be added to the plot file. PLOT END
2.10. Check Stresses
2.10.1. FECS and FECM Commands (SHELL data only) Specifies an effective surface or membrane stress to be used as the check stress to be applied to subsequent average and principal stress calculations.
FECS
FECM stress
Parameters FECS
: keyword to denote that an effective surface stress is to be defined.
FECM
: keyword to denote that an effective membrane stress is to be defined.
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stress
Input Data
: check stress. (Real). A value of zero implies no checking.
Note If the FANM command is in operation for any of the loadcases then no stress checking will be carried out. Example
Command AVST 6 END
Current Check Stress Values FECS
FECM
0.0
0.0
0.0
150.0
200.0
150.0
FECM 150.0 AVST 1
2
END
FECS 200.0 PRST 5 END
2.10.2. VONM Command Specifies a user defined von Mises stress level against which the calculated von Mises stresses will be checked, for loadcases defined by subsequent AVST and PRST commands.
VONM
stress
Parameters VONM
: keyword
stress
: von Mises stress check value (Real). A value of zero implies no checking
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Note The stress check value remains for selected loadcases until it is overwritten by a subsequent VONM command. Example VONM 5.0
2.10.3. TRES Command Specifies a user defined Tresca stress level against which the calculated Tresca stresses will be checked, for loadcases defined by a subsequent PRST commands.
TRES
stress
Parameters TRES
: keyword
stress
: Tresca stress check value (Real). A value of zero implis no checking.
Note The stress check value remains for selected loadcases until it is overwritten by a subsequent TRES command. Example TRES 10.0
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2.11. Harmonic Combination Commands
2.11.1. Data for Harmonic Analyses If a Fourier series type of analysis is being carried out on the harmonic solid elements, THX3, QHX4, THX6 and QHX8, data must be defined for the constituent structures and loadcases (see Section 1.2.5). The following commands provide this additional information and must follow the HARM and BRICK / SHELL command.
ANGL angl
END
COMB
numcomb
SELE
new case
STRUCTURE
struct
COMPONENT
struct
title
tree
COS
SIN loadcase
factor
END
Parameters See following sections for details of each command.
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Note The harmonic combination commands must be omitted in a harmonic re-run and the loadcase details will be obtained from the previously saved files.
2.11.2. ANGL Command (HARM Data only) Specifies the angular positions around the structure at which stress output is required.
ANGL angle
END
Parameters ANGL
: keyword
angle
: angle at which results are required. (Real)
END
: keyword to denote the end of the angle data.
Notes 1.
A maximum of 50 angular stations are permitted.
2.
Continuation lines are permitted, the END appearing at the end of the last continuation line.
3.
The ANGL command is compulsory for all HARM data files and must be the first data after the HARM BRICK / SHELL data type commands.
Example ANGL 20.0
33.0
42.0
57.0
30.0
END
2.11.3. COMB Command (HARM data only) Specifies the number of harmonic combinations which are to be created by this run.
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COMB
Input Data
numcomb
Parameters COMB
: keyword
numcomb
: number of harmonic combinations to be created. Must be 9 or less. (Integer)
Note The COMB command must immediately follow the last ANGL command Example COMB 3
2.11.4. SELE Command (HARM data only) This command identifies the combination number and title to be associated with the harmonic combination created by the subsequent commands.
SELE
combno
’title’
Parameters SELE
: keyword
combno : user combination number for this case (Integer) This value must be 9 or less (see note below). title
: combination title, up to 40 characters.
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Notes 1.
The combination number specified on the SELE command line is used in conjunction with the specified angular positions to generate internal loadcase numbers for reporting results.
2.
The combination number defined on the SELE command is multiplied by 1000 and added to the integer angle of a station (in degrees) to arrive at a representative loadcase number. For example, if the SELE command defines a new combination 5 and angles of 20.0, 32.0 and 47.0 degrees have been specified on the ANGL command, the following internal loadcases will be generated:- 5020, 5032 and 5047.
3.
There must be as many SELE commands supplied as the number defined on the COMB command.
Example SELE
2
’CASE 7 HARMONIC 0 + CASE 5 HARMONIC 2’
2.11.5. COS and SIN Commands (HARM data only) Specifies constituent loadcase numbers and factors to be used in the generation of a harmonic combination, together with optional information defining the structure or component to which the loadcases are relevant.
STRUCTURE
struct
COMPONENT
struct
tree
COS
SIN loadcase
factor
END
Parameters STRUCTURE :
keyword
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struct
Input Data
: 4-character ASAS structure name identifying which structure within the current project is to be accessed
tree
: this is the path down the component tree from the given structure in sname to the component being used for the POST combinations. If processing a global structure run from a multilevel analysis, i.e. the component tree is not required, use the STRUCTURE command instead.
COS
: keyword to indicate that the loadcases selected are symmetrically expanded about the reference direction ( =0.0), i.e. the loading is maximum at =0.0)
SIN
: keyword to indicate that the loadcases selected are antisymmetrically expanded about the reference direction ( =0.0), i.e. the loading is maximum at an angle of = /2n, where n is the harmonic number
loadcase
: constituent ASAS loadcase number (Integer)
factor
: factor by which the constituent loadcase is to be multiplied (Real)
END
: keyword to denote the end of the current block of constituent loadcase information. Required on the last COS or SIN command for the current SELE command.
Note If all the constituent load information is from one ASAS run, i.e. as defined in the Preliminary data, the COMPONENT and STRUCTURE commands are unnecessary. If the loadcase information is drawn from more than one component or structure, the appropriate command should precede the relevant COS or SIN command. Having specified the STRUCTURE or COMPONENT in this way, POST will continue to draw information from the loadcase selection commands accordingly. To avoid ambiguities it is recommended that the STRUCTURE or COMPONENT commands be defined explicitly at all times. Example Loadcases 1, 2 and 3 are taken from the assembled component defined in the Preliminary data. To these are added loadcases 5 and 7 from assembled component CMP9 of structure WQH2. SELE
6
COS 1 1.3
COMBINED LOADCASE 2
2.4
SIN 3 -2.3 COMPONENT WQH2 CMP9 SIN 5 1.0 COS 7 2.0 END
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2.12. Miscellaneous Commands
2.12.1. SECT Command Specifies a section across which stresses are to be calculated and printed for the loadcases defined with the AVST command. This command is only valid for AXIS type jobs or to process summed out of plane shears for TRB3 elements (see Section 1.7). SECT
igroup
sectid
END
sectid
nodenm
END
Parameters SECT
: keyword
igroup
: the ASAS group number across which the sectional stresses are to be calculated (Integer).
sectid
: identifying number for each section defined across the ASAS group.
nodenm : node numbers defining the section. (Integer). END
: keyword to denote the end of the current block of data. If the list of node numbers continues onto subsequent lines, END is required on last line only.
Notes 1.
For each section identifier defined on the igroup line, there must be a related sectid line.
2.
Up to 17 nodes may be specified across a section. These nodes should form a ”straight” line although they do not necessarily have to follow the edge of an element (the section may pass diagonally across elements). The nodes defining a given section must be in the same order as the nodes across the ASAS model.
3.
Each section may be at any angle to the global axis system. A new reference plane, defined by the first and last nodes in the list, will be calculated for each section. All averaged nodal stresses are then resolved normal and parallel to this plane before the member components are evaluated.
Example Three sections are to be numbered 22, 23 and 24, taken across ASAS group number 2. Section 22 has nodes 1, 8, 9, 10 and 14 across it
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Section 23 has nodes 11, 18, 19, 20 and 24 across it Section 24 has nodes 21, 28, 30, 34 and 29 across it SECT 2 22 22 1 23 11 20 24 21
-24 8 18 24 28
END 9 10 19 END 30 34
14
END
29
END
2.12.2. ANGL Command (SHELL data only) Requests output of the direction of first principal stress instead of (P 1 - P2)
ANGL
Parameters ANGL
: keyword
Notes 1.
If present, the angle of the first principal stress measured from the output x-axis is reported instead of the principal stress difference (P1 - P2).
2.
This command should not be confused with the ANGL command in a HARM run. (See Section 2.11.2)
2.12.3. END Command Specifies the end of the data. This command must be present.
END
Parameters END
: compulsory keyword
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3.
Examples
Examples
3.1. Example 1: Default Data This example shows the minimum of data necessary to run POST. The preliminary data defines the space required (30000 words), the project name and the ASAS results to be processed (LVW1, a single level analysis), a title and the option GOON (to prevent termination if any warnings are issued). Two POST commands are used: SHELL to indicate that the shell elements of LVW1 are to be processed and END to denote the end of the post data. For this particular example it is assumed that the local axes of the shell elements are consistent. POST will also make this assumption and print a warning which necessitates the GOON option in the preliminary data. Similar default data may be used for each of the POST data types by substituting the appropriate data type keyword. POST will process all loadcases and print average and principal stresses. No files will be saved for plotting. SYSTEM DATA AREA 30000 PROJ LVW1 JOB POST TITLE POST PROCESSING FOR LVM MODEL OPTION GOON END END SHELL END
3.2. Example 2: Simple Shell Result Processing This example shows the data file for running POST after a single level ASAS analysis. The structure name to be accessed is SBSS from project SBSS. As the elements within each group are all aligned similarly with regard to the global axes, the CONS option is selected. Elements from Groups 1, 3, 5, 6, 7 and 9 are to be processed. The mid-plane check stress is 50.0 and the surface check stress is 75.0. The average stresses and principal stresses are to be processed for user loadcases 1, 3, 7 8, 9, 10, 11 and 14. The average stresses and principal stresses are to be printed for user loadcases 1 and 10. All processed stresses will be written to a FEMVIEW file with default filename SBSSFS and default model name SBSS. SYSTEM DATA AREA 35000 PROJ SBSS JOB POST TITLE EXAMPLE ILLUSTRATING SHELL DATA STRUCTURE SBSS OPTIONS END
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SAVE FEMS FILES END SHELL CONS GROU 1 3 5 -7 9 END FECM 50.0 FECS 75.0 AVST 1 3 7 -11 14 END PRST 1 3 7 -11 14 END PRIN 1 10 END END
3.3. Example 3: Simple Axi-symmetric Result Processing This example shows the data deck for running POST after a single level ASAS analysis. The structure to be accessed is named is ROTA. Elements from Groups 1, 3, 5, 6, 7 and 9 are to be processed. The von Mises check stress is 50.0 and the Tresca check stress is 75.0. The average stresses for all loadcases are to be processed, and principal stresses for user loadcases 1, 3, 7, 8, 9, 10, 11 and 14. The average stresses and principal stresses are to be printed for user loadcases 1 and 10. All processed stresses will be written to a FEMVIEW file called ROTA.FVI with a model name ROTOR. SYSTEM DATA AREA 35000 PROJ ROTA JOB POST TITLE EXAMPLE ILLUSTRATING AXIS DATA STRUCTURE ROTA OPTIONS END SAVE FEMS FILES CREATE ROTOR FILE ROTA.FVI END AXIS GROU 1 3 5 -7 9 END VONM 50.0 TRES 75.0 AVST
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ALL PRST 1 3 7 -11 14 END PRIN 1
10
END
END
3.4. Example 4: Post Processing Component Results from Multi Level Axisymmetric Analysis This example considers elements in component MLS1 which has been assembled into structure MLST. Elements in groups 1, 3 and 5 are selected. One section (numbered 19) is taken from ASAS group 1 on a plane defined by nodes 28 and 49 and passing through nodes 29, 30 and 48. Averaged stresses will be printed for loadcases 1, 4, 5, 6 and 7. Next an extra group, number 15, is formed of user elements numbered 31 to 36, 40 and 62 to 70. This extra group has von Mises and Tresca check stress levels of 25.0 and 37.5 and the averaged stresses will be printed for loadcases 2, 3, 8, 9 and 10. SYSTEM DATA AREA 40000 PROJECT MLPJ JOB POST TITLE AXIS DATA WITH EXTRA GROUP STRUCTURE MLST COMPONENT MLST MLLB MLS1 OPTIONS END END AXIS GROU 1 3 5 END SECT 1 19
END
19 28 29 30 48 49 END AVST 1 4 5 -7 END EXTRA 15 31 -36 40 62 -70 END VONM 25.0 TRES 37.5 AVST 2 3 8 -10 END END
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3.5. Example 5: Loadcase Combinations This example considers elements in component MLS1 which has been assembled into structure MLST. The elements considered do not all have consistently oriented local axes and hence the OUTP and OUTR commands are given to define new output axis systems. Firstly a cartesian output axis system is defined using the OUTP command. This will then be used for elements in groups 1 3 and 5. A new radial output system is then defined using the OUTR command. This will then be used for the elements which are defined as a new group using the EXTR command and also for elements in groups 2 and 4. The new group will be group 16 consisting of elements 75 to 80 and 82. In all these groups user elements numbered 37 to 39, 43 to 47 and 51 to 53 are to be omitted from the calculations. Mid-plane and surface check stresses of 50.0 and 75.0 are set and the averaged stresses and principal stresses will be printed for loadcases 1, 4, 5, 6 and 7. Next the output axis system is set back to consistent axes using the CONS command, and a new extra group, number 15, is formed of user elements numbered 31 -36, 40 and 62 -70. This extra group has mid-plane and surface check stress levels of 25.0 and 37.5. Two new loadcases are formed, 101 by adding together cases 1 and 4 and factoring by 1.05 and 102 by adding case 4 factored by 1.25 and case 6 factored by -0.5. The averaged stresses will be printed for loadcases 2, 3, 8, 9, 10 and 101. Note, the FACT command is used to reset the factor to 1.0 before printing. SYSTEM DATA AREA 40000 PROJECT MLPJ JOB POST TITLE
SHELL DATA WITH EXTRA GROUPS AND OUTPUT COMMANDS
STRUCTURE MLST COMPONENT MLST MLLB MLS1 OPTIONS END END SHELL OUTP 0.5
0.8660
0.0
25.0
0.0
0.0
GROU 1 3 5 END OUTR 1.0
0.0
10.0
1.0
0.0
2.0
EXTRA 16 75 -80 GROU 2 4 SKIP
82 END
END
37 -39 43 -47 51 -53 END FECM 50.0 FECS 75.0
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AVST 1 4 5 -7 END PRST 1 4 5 -7 END CONS EXTRA 15 31 -36 40 62 -70 END FECM 25.0 FECS 37.5 NEWC 101 102 END 101 COMBINATION OF CASE 1 AND 4 102 FACT
COMBINATION OF CASE 4 AND 6
1.05 ADDC 101 1
4
ADDF 102 4
1.25
END 6
-0.5
END
FACT 1.0 AVST 2 3 8 -10 101 END END
3.6. Example 6: Post Processing Harmonic Analyses This data file runs POST for a HARMonic analysis. One new loadcase is generated which is just case 1, with an antisymmetric expansion about =0, of STRUCTURE WQH1. Stress output is generated for angle =20 only. Note, this will have loadcase 5020 on its printout. SYSTEM DATA AREA 60000 PROJ WQX8 JOB POST FILE WHHH TITLE
SIMPLE HARMONIC EXAMPLE
STRUCTURE WQH1 NEWSTRUCTURE WHHH OPTIONS END SAVE FEMS FILES END
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HARM ANGL 20.0 END COMB 1 SELE 5 LOADCASE 1 of WQH1 STRUCTURE WQH1 SIN 1 1.0 END END
3.7. Example 7: Harmonic Combinations This example produces two new loadcases (5, 6) from the stress results from structures WQHO, WQH1, WQH2, WQH3, and WQH4. Output is requested at angles 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 and 120 degrees. The output will refer to loadcases 5020, 5030, 5040 ..... 5110, 5120, 6020, 6030 .... 6110, 6120. Each combined loadcase accesses each structure and more than one loadcase from each original structure. As no PRST or AVST command appears, the output will include both principal and average stress results. SYSTEM DATA AREA 60000 PROJ WQX8 JOB POST FILE WHHH TITLE STRUCTURE WQHO
FULL HARMONIC EXAMPLE
NEWSTRUCTURE WHHH OPTIONS END END HARM ANGL 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 END COMB 2 SELE 5 1ST COMBINED LOADCASE COS 2 1.0 3 1.0 STRUCTURE WQH1 COS 2 1.0
3 1.0
STRUCTURE WQH2 COS 2 1.0 3 1.0
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STRUCTURE WQH3 COS 2 1.0 3 1.0 STRUCTURE WQH4 COS 2 1.0 3 1.0 END SELE 6 2ND COMBINED LOADCASE STRUCTURE WQHO COS 1 1.0 2 1.0 3 3.0 STRUCTURE WQH1 COS 1 1.0 2 2.0 3 3.0 STRUCTURE WQH2 COS 1 1.0 2 2.0 3 3.0 STRUCTURE WQH3 COS 1 1.0 2 2.0 3 3.0 STRUCTURE WQH4 COS 1 1.0 2 2.0 3 3.0 END END END
3.8. Example 8: Post Processing Shell Compatible Beams This example shows the data for running POST after an ASAS analysis which includes shell BEAM elements (TCBM or GCB3). It is assumed that all the beam elements in groups 1 2 and 3 have consistent local axis and that the user wishes to have the moments/forces reported in the element local axis. Groups 4, 5 and 6 are to be reported in a new output axis system defined by the preceding OUTB command. Three new loadcases have been formed. The first two have the same combination factors, one representing the positive (or maximum) limit stress value, the second the negative (or minimum) limit stress value. The third new loadcase takes the first two new cases and finds the absolute envelope, giving the overall worst absolute values. Finally the forces/moments for all loadcases are to be printed out. Since a SAVE FEMS FILES command is present in the preliminary deck, all results will be saved for plotting in FEMVIEW. Since APPEND is specified, no model data (coordinates and element definitions) will be added to the plot file.
If the plot file
STIFFNER.FVI already exists the results will be appended to it. If not then the new STIFFNER.FVI file can be read into FEMVIEW if the model data already exists for model STIFNR. SYSTEM DATA AREA 35000 PROJECT STIF JOB POST
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TITLE EXAMPLE ILLUSTRATING SBEAM DATA STRUCTURE STIF OPTIONS END SAVE FEMS FILES APPEND STIFNR FILE STIFFNER.FVI END SBEAM CONS GROU 1 2 3 END OUTB 0.0 1.0 0.0 0.0 0.0 1.0 GROU 4 5 6 END NEWC 101 102 103 END 101 MAXIMUM LIMIT STRESS CASE 102 MAXIMUM LIMIT STRESS CASE 103 MAXIMUM ABSOLUTE ENVELOPE OF CASES 101 & 102 ADDF MXLS 101 1 1.3 1.0 2 1.0 1.0 3 1.3 -1.3 END ADDF MNLS 102 1 1.3 1.0 2 1.0 1.0 3 1.3 -1.3 END ADDC MXAE 103 102 101 END AVST ALL END
3.9. Example 9: Post Processing Laminated Shells This example shows the data deck for calculating laminate layer stresses with POST following an ASAS analysis using laminated shells. For the ASAS groups 1 and 2 only the stresses of layers 1, 2, 5 and 6 are to be reported (these may be the top and bottom two layers of the composite section). In addition a new group (group 11) has been formed from elements 1 to 20 for which all the layers are to be processed. Finally a new loadcase has been formed consisting of the summation of ASAS loadcases 1 and 2. SYSTEM DATA AREA 35000 PROJECT COMP JOB POST TITLE EXAMPLE ILLUSTRATING LAMI DATA OPTION GOON END SAVE FEMS FILES END LAMI LAYE
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1 2 5 6 END GROU 1 2 END LAYE ALL EXTR 11 1 TO 20 END NEWC 101 END 101 LOADCASE 1 + LOADCASE 2 ADDF 101 1 1.0 2 1.0 END END
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4.
Output
Output
Three forms of output are available from POST, the printed stress output, a backing file that may be used for further post-processing, and the sequential files required as input for a variety of proprietary plotting packages.
4.1. Printed Output The printed output consists of the data check, followed by the stress output, listed group by group. Within each group the average surface stresses and also the principal stresses are listed if requested for each loadcase in turn. The exact form of the output will depend on the type of data being analysed, and is discussed in further detail in the subsequent sections of this manual.
4.1.1.
SHELL Data
The average surface stresses are printed for the top, bottom and mid-surfaces of the element (as defined in Section 2.1). These stresses are given in terms of the output axis system, as defined by the OUTP or OUTR commands, or the local element axis system in the case of consistent axes. This set of output also includes the number of elements contributing to the nodal average and the maximum variation in stress at the particular node. The variation shows the user the level of the stress difference between adjacent elements at the same node and also indicates on the accuracy of the overall stresses. In the cases of high variation compared to averaged stresses, the accuracy of the model should be checked. The in-plane principal stresses P1 and P2 together with the principal stress difference (P 1 and P2) are printed for each of the three surfaces. Two check stresses are also printed at the head of each page of principal stress output. These are the mid-plane (membrane) and the surface (membrane plus bending) stress allowables FECM and FECS respectively, and are defined by the user for the particular loadcase. At each node the „effective‟ stress on each of the three surfaces is checked against the allowable stress - that is the top and bottom surface effective stresses are compared with FECS and the mid-surface effective stress is compared with FECM. The maximum of the surface stress ratios and the mid-plane stress ratio are printed only for values greater than unity under columns headed FECS and FECM respectively. In the above, the effective stress is the Tresca stress T
T
where:
= max. absolute of P1, P2, (P1 - P2)
Asterisks are used throughout the printout to highlight maximum values of P1, P2, (P1, - P2) and the stress ratio. The backing file, when saved, contains the information required to plot the stress contours for both principal stresses and averaged nodal stresses for each loadcase of every group considered in the POST run. If the user has specified some of the options (BANM, FANM, WOOD) which produce SHELL output with forces and/or moments instead of the surface stresses the same procedures are followed as described above. The
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principal and average values will, however, relate to the net section forces and moments rather than to individual surface stresses. If the SHRS command is used, only the out-of-plane shear forces are reported.
4.1.2.
LAMI Data
The direct stresses in the fibre direction and to the normal fibre direction and the inshear stresses are presented for each of the layers requested at each node on a group basis.
4.1.3.
Shell BEAM Data
The results for shell beams are presented as forces and moments in the output axis system defined by the OUTB command, or the local element axis in the case of the CONS command. In addition to the forces and moments, a variation value is printed giving an indication of the force/moment variation at a node common to two or more elements.
4.1.4.
BRICK, AXIS and HARM Data
The average nodal stress output gives the direct stress in the three global directions and also the three shear stresses in these directions. The von Mises stress is also calculated and listed for each node. The user defined allowable stress is listed at the top of each page of output; where it is exceeded the ratio of the von Mises stress to the allowable is printed in the „EXCESS‟ column. The principal stress output gives the three principal stresses at each node and also the sum of the principal stresses and their direction cosines or principal angle. (For AXIS data, the hoop stress
HH
is a principal stress).
The von Mises and Tresca stresses are also printed for each node. The Tresca stress is checked against the user defined allowable which is printed at the top of the page. When the allowable is exceeded the ratio of the Tresca stress to the allowable is printed in the „EXCESS‟ column.
4.2. Backing Files The backing file, or intermediate file, is used within POST to temporarily save data that will be written to a plot file or used in loadcase combination/enveloping. It contains information on both the form of the model (nodes, elements groups etc) and calculated stress results. For this reason it is a useful file if further processing of results is to be undertaken. If it is required then it may be saved using SAVE INTE FILE in the preliminary deck. The saved file will be called XXXX12 where XXXX is the 4 character structure name. If a subsequent run of POST is made on the same structure and an intermediate file is found to exist then post will try to append data from the current run. Before it can do this it has to check for any inconsistencies on the
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intermediate file with the current run. Such inconsistencies include different element groupings and conflicting loadcase numbering. In this event the current run would be terminated. In some cases it is desirable to overwrite an existing intermediate file rather than append to it. This can only be achieved by using SAVE NEWP FILES in the preliminary data. It is not recommended to delete the old intermediate file, since its existence is determined from the project index file not its physical existence, hence deleting the 12 file will require you to re-run in order to correct the project file referencing. If the RESU command is specified in the preliminary data, the results from POST will be saved to a file called XXXX45.
4.3. Plotting Program Input This section describes the contents of the file(s) produced by POST for input to different plotting packages.
4.3.1.
FEMVIEW Input
FEMVIEW uses a formatted file that is created when the SAVE FEMS FILES command is present in the preliminary data. By default the file will be saved as nnnnFS where nnnn is the four character backing file name. This may be overridden by specifying a file name explicitly on the SAVE FEMS FILES command (Appendix A-). The exact format of the FEMVIEW file is described in detail in the FEMGEN/FEMVIEW user documentation (Appendix B-). This section will only give a brief overview of the file format, sufficient for the user to be able to understand the data within it. The data is divided into a series of „data decks‟, each of which begins with a header line and a terminator line (consisting of -3 only). The first number on the header line defines the type of data that follows. The following are used in the POST created file: 1
-
user header defining model name (no corresponding terminator line)
2
-
nodal coordinates
3
-
element connectivity
100
-
results data
9999
-
end of data file
If APPEND is defined in the SAVE FEMS command then data types 2 and 3 will not be written. These may already be in the file to which the data is being appended. The data type number is followed by either C (for create, if model data present) or A (for append, no model data present). On the user header line this is followed by the model name to be used by FEMVIEW. By default this is the four character backing file name, but may be defined explicitly on the SAVE FEMS FILES command. Note that if EXTR groups are created in POST, then the CREATE Command should be used on the SAVE FEMS line. The nodal coordinate data and element connectivity are self explanatory except that on the elements the group number is output in place of the material number required by FEMVIEW. The reason for this is that POST
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averages stresses on a group basis and so a node may have different stresses for each of the groups, which can only be accommodated by FEMVIEW by material based nodal results. This has repercussions throughout the ASAS suite of programs, the material and group numbers being swapped over to maintain compatibility with POST. The results data header is followed by a loadcase name, made up of „L‟ followed by the loadcase number, and the loadcase title truncated to 20 characters. This is followed by further headers that give the name of the results set, the type of results, and the names of each component of the results. Two basic results types are used, material based nodal results and element nodal results, the latter being used only for the SBEAM results. Where the results are in the global axes system they are written in a matrix form allowing FEMVIEW to calculate principal stresses and present vector diagrams of principal stresses. For multi-surface results (e.g. shell/plate stresses), the results are written from bottom surface to top surface. Thus, surface 1 is the bottom surface.
4.3.2.
PATRAN® Input
PATRAN® displays any defined stresses at each node. In POST stresses are calculated on an element group basis and, therefore, any node lying on a boundary between two or more element groups can have more than one set of stresses. To overcome this problem each element group is output to a separate file generated by POST. Two files per group are generated, the first containing average stresses, the second containing principal stresses. SBEAM result cannot be plotted in PATRAN®.
4.3.2.1. The PATRAN® Results File Each PATRAN® Results file generated by POST is assigned a different file name. This file name is made up from the first 4 characters given on the line following the NAME command. Appended to this is a 4 digit integer starting at 0001 and increment by 1 for each file output. Finally, the 4 characters .NOD are added to indicate that the values are nodal stresses. The type of stress contained in any file, average or principal, is indicated in the title record on the file. This title is also printed in the POST output together with the corresponding file name. The structure of the PATRAN® input file depends upon the stress output requested. The file is written as binary or formatted depending on the save option PATN or PTNC. Record 1 for non-lamina stresses
85 1-80 81 82-84 85
Record 1 85 for lamina 1-7 „ GROUP ‟
Words Title (First byte of each word only - A1 format) No. of nodes in the group (NNOG) Dummy No. of stresses on each record (NST) Words
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stresses
8-12 13-23 24-28 29-48 49-53 54-80 81 82-84 85
Record 2 Record 3
80 80
Record 4
NST+1 1 2-(NST+1)
. . Record NNOG+3
Output
Group number „ LOAD CASE ‟ Loadcase number „ LAMINA STRESS ‟ No. of layers Dummy No. of nodes in the group (NNOG) Dummy No. of stresses on each record (NST=3 x No. of layers) Words. Subtitle. Contains all blanks Words. Subtitle. Contains all blanks Words Node number The stresses for that node
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4.3.2.2. PATRAN® Results File for each Analysis Type Each type of analysis processed by POST will write a different set of nodal stresses to the PATRAN® results file. The correspondence between analysis type and the stress written to file is shown in Tables 4.3 and 4.4.
Stresses
No. of Stresses
Element
Surface xx
yy
zz
xy
yz
xz
AXIS
4
RR
HH
ZZ
RZ
HARMONIC
6
RR
HH
ZZ
RZ
ZH
RH
BRICK
6
xx
yy
zz
xy
yz
zx
SHELL
9
xx
yy
xy
T
xx
yy
xy
M
xx
yy
xy
B
xx
yy
xy
T
xy
B
xy
M
xy
1 to NLAY
PLATE
9 0
0 xx
MEMBRANE
9
0
yy
0 xx
0 LAMI
3*NLAY
0
0 yy
0 xx
0 yy
Notes T NLAY
M
B
refer to top, middle and bottom surfaces respectively number of layers in laminate Table 4.3 Average Stresses Written to Patran® Results File
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Stresses No. of Stresses
Element
AXIS
7
HARMONIC
BRICK
12
12
SHELL
12
PLATE
12
MEMBRANE
12
N1 N3
Surface
P1 L2
P2 M2
P3 N2
L1 L3
M1 M3
P1
P2
Ph
L1
M1
L2
M2
P1
P2
P3
L1
M1
N1
L2
M2
N2
L3
M3
N3
P1
P2
P3
L1
M1
N1
L2
M2
N2
L3
M3
N3
P1
P2
(P1-P2)
T
P1
P2
(P1-P2)
M
P1
P2
(P1-P2)
B
Tresca(T)
Tresca(M) Tresca(B)
P1
P2
(P1-P2)
0
0
0
P1
P2
(P1-P2)
Tresca(T)
0
Tresca(B)
0
0
0
P1
P2
(P1-P2)
0
0
0
0
Tresca(M) 0
T
B
M
Table 4.4 Principal Stresses Written to Patran® Results File Note P1 Ph L1
P2
P3
M1
N1
are principal stresses hoop stress are direction cosines for P1
L2
M2
N2
are direction cosines for P2
L3 T
M3 M
N3 B
are direction cosines for P3 refer to top, middle and bottom surfaces respectively
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Appendix A
Appendix A A.1
Preliminary Data Block for POST
Introduction
The preliminary data is the first block of the LOCO data. It defines the memory size to be used, the project name, structure and component names, file names and options to be used. It also defines which files are to be saved for further processing.
SYSTEM
DATA AREA
PROJECT
pname
JOB
POST
FILES
fname
TITLE
title
TEXT
text
STRUCTURE
sname
COMPONENT
sname
NEWSTRUCTURE OPTIONS
UNITS SAVE
memory
tree
nsname option
unitm
resultnm set
(FILES)
RESU END
The preliminary data must commence with the SYSTEM command and terminate with END. Within these bounds the other commands may be given in any order. It is suggested, however, that the order given above is adopted.
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A.2
Appendix A
SYSTEM Command
To define the amount of memory used for data by this run. Optional. SYSTEM
DATA AREA
memory
Parameters SYSTEM
: keyword
DATA AREA memory
:
keyword
: amount of memory (in 4 byte words) to be used by this run. Typical values are between 30000 and 1000000. If the SYSTEM command is omitted, a default value of 1000000 is used. (Integer)
Examples SYSTEM
A.3
DATA AREA 80000
PROJECT Command
To define the project name for the current run. Optional. PROJECT
pname
Parameters PROJECT
: keyword
pname
: project name for current run. (Alphanumeric, 4 characters, first character must be alphabetic)
Note All runs with the same project name access the same data base. A project data base consists of one project file (with a file name consisting of the 4 characters of pname with the number 10 appended) which acts as an index to other files created under this project, together with those other files. Example PROJECT HIJK
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A.4
Appendix A
JOB Command
To define the type of analysis being performed. Compulsory. JOB
POST
Parameters JOB
: keyword.
POST
: keyword.
Example JOB
A.5
POST
FILES Command
To define the prefix name for the backing files created in this run. Optional.
FILES
fname
Parameters FILES
: keyword.
fname
: prefix name for any backing files created by this run. (Alphanumeric, 4 characters, first character must be alphabetic)
Note fname is used as a prefix for all files created during the current run. The four characters are appended with two digits in the range 12 to 35 to create each individual file. Example FILES
A.6
BILL
TITLE Command
To define a title for this run. Recommended.
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TITLE
Appendix A
title
Parameters TITLE
: keyword
title
: this line of text will be printed out at the top of each page of ASAS output. (Alphanumeric, up to 74 characters)
Example TITLE
A.7
THIS IS AN EXAMPLE OF A TITLE LINE
TEXT Command
To define a line of text to be printed once only at the beginning of the output. Several TEXT lines may be defined to give a fuller description of the current analysis on the printed output.
TEXT
text
Parameters TEXT
: keyword
text
: this line of text will be printed once, at the beginning of the output. (Alphanumeric, up to 75 characters)
Example
A.8
TEXT
THIS EXAMPLE OF THE TEXT
TEXT
COMMAND IS SPREAD
TEXT
OVER THREE LINES
STRUCTURE Command
To define the name of an existing structure within the current project that is to be processed in this run.
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STRUCTURE
Appendix A
sname
Parameters STRUCTURE : sname
keyword
: structure name identifying which existing structure is to be accessed from the project defined on the PROJECT command.
(Alphanumeric, 4 characters, the first character must be
alphabetic) Note For harmonic combinations the loadcase information to be processed may be drawn from more than one structure and this is achieved by respecifying a STRUCTURE command within the COMBination data (see Section 2.11.3). The structure defined in the preliminary data is adopted until a new STRUCTURE command is supplied. For harmonic re-run, the structure name should identify the files that contain the combined loadcase information. See also A.9 COMPONENT command. Example STRUCTURE SHIP
A.9
COMPONENT Command
For substructure analyses, this command defines the recovered component being processed in the current run.
COMPONENT
sname
tree
Parameters COMPONENT
: keyword
sname
: structure name as defined on the previous STRUCTURE command. (Alphanumeric, 4 characters, the first character must be alphabetic)
tree
: this is the path down the component tree from the given structure in sname to the component which is being used for POST post-processing.
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Appendix A
Notes (i)
If the user is processing the global structure run in a substructure analysis, use only the STRUCTURE command (A.8).
(ii)
For harmonic combinations the loadcase information to be processed may be drawn from more than one structure and this is achieved by respecifying a COMPONENT command within the COMBination data (see Section 2.11.3). The structure defined in the preliminary data is adopted until a new COMPONENT command is supplied.
Example To process the second level component, CMP2, which is part of assembled component CMP1, which is part of structure STRU. COMPONENT STRU CMP1 CMP2
A.10
NEWSTRUCTURE Command
This command is only needed for HARM data type and is used to identify the results being created. However, in this case the new structure name will not be permanently saved in the project file if no SAVE or RESU command is specified. In this case, the same new structure name may be used repeatedly within one project.
NEWSTRUCTURE
nsname
Parameters NEWSTRUCTURE : keyword nsname
: new structure name. This must be unique within the current project (but see note above). (Alphanumeric, 4 characters, the first character must be alphabetic)
Example NEWSTRUCTURE
NSTR
Notes NEWSTRUCTURE command is not needed in a harmonic re-run where the loadcase combination data are omitted.
A.11
OPTIONS Command
To define the control options for this run. Optional.
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OPTIONS
Appendix A
option
Parameters OPTIONS
: keyword
option
: 4 character option name, or list of option names. See table below for details of the options available
Note The following options are available in POST:
Option Name
Application
DATA
Stop after checking the data and do not process the stresses.
GOON
Proceed even after printed WARNINGS. This option allows the program to continue despite doubtful data. It should be used after a run in which the WARNINGS have been noted and rejected.
NOBL
Do not print the POST title page.
CCGO
Proceed with stress averaging even after thickness and/or offset discontinuities are encountered within an element group, see Section 1.4.
GLST
Print shell element stresses to FEMVIEW file in global stress format. This allows the FEMVIEW stress calculation facilities to be used. Note: This does not convert the FEMVIEW stresses into the global system and so vector plots may be misleading.
UPLT
Write any unity stress values computed in the current run to the plot file. Unity stress values are computed when check stress values are defined, see Section 2.10.
OAIS
The material axis definition for anisotropic shells changed with the issue of POST version H11.3. This option allows the user to continue to employ the old material axis definition if needed. It is required if and only if the structural analysis was undertaken using a version of ASAS prior to H11.3, or the complementary OAIS option has been used in the ASAS run.
Example OPTIONS
DATA
GOON
END
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A.12
Appendix A
SAVE Command
To define the plot file which is to be saved for subsequent display by the relevant plotting program, or to save the intermediate file
SAVE
FEMS
(FILES)
SAVE
prog
(FILES)
SAVE
INTE
(FILES)
SAVE
NEWP
(FILES)
CREATE
(model)
(FILE)
(filename)
APPEND
Parameters SAVE
: keyword
FEMS
: keyword to save the FEMVIEW plot file
prog
: mnemonic to define the plotting program name. Valid names are:
(FILES)
PATN
-
PATRAN nodal results file, binary
PTNC
-
PATRAN nodal results file, formatted
: keyword
CREATE : keyword to signify model data is to be included (default) APPEND : keyword to signify no model data to be included model
: model name to be used by FEMVIEW
FILE
: keyword to indicate filename follows
filename : name of FEMVIEW file to be created INTE
: keyword to save the intermediate file and append data to it if necessary
NEWP
: keyword to save the intermediate file and overwrite existing file if necessary
Notes 1.
The plot files are mutually exclusive and only one may be specified within any POST analysis.
2.
CREATE/APPEND and following data is only valid for prog = FEMS
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Appendix A
3.
FILE may only be omitted if model is specified
4.
Note that if EXTR groups are created in POST, then the CREATE Command should be used on the SAVE FEMS line.
Example SAVE PATN FILE
A.13
RESU Command
To specify saving of results. The results processed by POST will be added to the database.
RESU
Parameters RESU
:
keyword
Example RESU
A.14
UNITS Command (not valid for fixed format ASAS data)
If UNITS have been employed in the ASAS analysis it is possible to specify modified units for the POST results. The default units will be those utilised in the original analysis and if this is satisfactory the UNITS command may be omitted. UNITS
STRE
unitm
Parameters UNITS
: keyword
STRE
: keyword
unitm
: name of unit to be utilised (see Section 2.2)
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Appendix A
Notes 1.
If the results from more than one structure or component are being combined in a HARM type analysis, the analysis units must be identical
2.
Only those terms which are required to be modified need to be specified, undefined terms will default to those supplied on the global units definition.
3.
For a full list of valid unit names see Section 5 of the ASAS User Manual.
Example The global units defined in the ASAS run are N and M. If the units are redefined in the POST runs as follows: UNITS
STRE
MM
the stress results will be reported in N/mm2.
A.15
END Command
To terminate the preliminary data. Compulsory.
END
Parameters END
: compulsory keyword
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Appendix A
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Appendix B B.1
Appendix B
- Running Instructions for POST
ASAS Files Required by POST
POST operates on the files produced by the preceding ASAS or LOCO analysis. The appropriate files must physically be present in the user‟s disk space for the program to run successfully. In all cases the Project File must exist which contains information about all other files in the current set of analyses. The name of this file is derived from the four character Project name defined on all PROJECT commands in the set. For example, if the project name is PRDH, then the Project File will be PRDH10. The appropriate results for running POST will be saved when a „SAVE LOCO FILES‟ or a ‟SAVE STRESS FILES‟ command appears in the preliminary data of the ASAS or LOCO data. The file name will be derived from appending 35 to the four character name on the FILES command of the ASAS or LOCO preliminary data. This name will also appear on the STRUCTURE command of the current preliminary deck (name2 in Appendix A-). For example, if this name had been RNDH, then the backing file containing stresses (and displacements) would be RNDH35. For a POST run on a substructured analysis the file name for the results is derived from the second four character name on the JOB command of the relevant stress recovery run. If this name has been SRGP then the file would be SRGP35. For a harmonic run accessing several structures the files required by POST are precisely analogous to those required by LOCO.
B.2
Running Instructions for POST
See the appendices in the ASAS User Manual for details on how to run any of the programs in the ASAS suite.
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Appendix B
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Appendix C -
Appendix C
- Equations used for Stress Calculations
The equations used for stress calculations are based on the averaged nodal stresses. These will be orientated according to the ASAS local element axes system unless an output axes system has been specified to reorientate the stresses.
C.1
Notation
Stresses and Moments
, xy , rr , rh , xx
, yz , hh , hz , yy
zz
Direct stress in X, Y and Z directions
zx
Shear stresses in XY, YZ and ZX planes
zz
Direct stresses in R, H and Z directions
zr
Shear stresses in RH, HZ, ZR planes
M xx , M yy , M zz M xy , M yz , M zx
Moments in X, Y, and Z directions Torques in XY, YZ and ZX planes
Principal Stresses
P1, P2 , P3
Principal stresses (P1 is the highest principal stress value) Principal stress angle (measured from the output X axes to the absolute maximum principal stress - not necessarily P1)
Equivalent Stresses V
von-Mises equivalent stress
T
Tresca equivalent stress
Wood -Armer Values
M Px , M Py M Nx , M Ny
Positive Wood-Armer moment in X and Y directions Negative Wood-Armer moment in X and Y directions Skew angle between reinforcement directions
Reinforcement Values
CT ,C B h
Reinforcement cover depths (top and bottom)
N x , N y , N xy * * N x, N y F RA Ax , A y fc
Equivalent in-plane loads in idealized layers
Thickness of slab
Loads to be resisted by reinforcing in X and Y directions Design stress for reinforcing Area of reinforcement required in X and Y directions Compressive force in concrete
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C.2
Appendix C
Stress Formulae
Principal Stresses: 2D Stress Field:
P1 =
P2 =
=
+
xx
yy
2 xx
+
yy
2
2 2 xy
4 xx - y y
-
2
tan-1 2
xx - y y
+
2 2 xy
4
xy
xx -
yy
3D Stress Field P1,P2 & P3 are given by theroots of the equation : P3-
xx +
yy+
zz
P 2+
yy+
xx
yy zz +
zz
2 2 2 xx - xy - yz- zx
2 xx yy zz + 2 xy yz zx - xx yz-
-
P
2 yy zx -
zz
2 xy
=0
Von-Mises Equivalent Stress: V=
P1 P1-P2 +P2 P2-P3 +P3 P3-P1
V=
1
V=
1
V=
2
2
2 xx +
xx - yy
2
rr- hh
2
2 yy-
+
yy- zz
2
+
hh - zz
2
+
zz - xx
+
zz - rr
- Solids
2
2
+3
+3
2 2 2 xy +3 yz+3 zx
2 2 2 rh +3 hz +3 zr
2 xx yy+ 3 xy
Tresca Equivalent Stress: T = maximum value of P1- P2 or P2-P3 or P3-P1 T = maximum
value of P1 or P2 or P1-P2
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- Solids
- Axi-symmetrics
- Shells
- Solids - Shells (P3=0)
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C.3
Appendix C
Wood-Armer Calculations
C.3.1 Wood-Armer Moments - Orthogonal Reinforcing Positive Moments:
MPx = Mxx + Mxy MPy = Myy + Mxy
If MPx < 0 then :
or
M xy
M Py = M y y +
If MPy < 0 then :
2
M Px = M xx +
M xx
M xy
2
Myy
and MPx = 0
and MPy = 0
If MPy < 0 then MPy = 0
If MPx < 0 then MPx = 0
Negative Moments:
MNx = Mxx - Mxy MNy = Myy - Mxy
If M Nx > 0 then :
M Ny = M yy -
M xy
or
If M Ny > 0 then :
2
M Nx = M xx -
M xx
M xy
2
Myy
and MNx = 0
and M Ny = 0
If MNy > 0 then MNy = 0
If MNx > 0 then = 0
Note : Wood - Armer Stresses are given by substituting
Px for MPx etc.
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Appendix C
C.3.2 Wood-Armer Moments - Skewed Reinforcing Positive Moments:
MPx=Mxx -2Mxycot
MPy=
Myy sin 2
+
+Myycot 2 +
Mxy-Myycot 2 sin
Mxy-Myycot 2 sin
If MPx< 0 then : MPx= 0 M Py=
1 sin 2
M y y+
2 M xy -M y ycot 2 M xx -2M xy cot +M y ycot
If MPy< 0 then : MPy= 0
MPx= M xx -2M xy cot
+M yycot
2
+
M xy -M yycot
2
M yy
Negative Moments:
MNx =Mxx -2Mxycot M Ny =
+Myycot 2 -
Mxy-Myycot 2 sin
M yy Mxy -M yycot 2 sin sin 2
If MNx > 0 then :
M Nx = 0 M Ny =
1 sin 2
M y y-
2 M xy -M y ycot 2 M xx -2M xy cot +M y ycot
If MNy> 0 then : M Ny = 0
M Nx = Mxx -2Mxycot
+M yycot 2 -
Mxy-M yycot
2
M yy
Note: In the original Wood-Armer papers the equations were derived using a left handed axis system. Since ASAS uses a right handed system the above equations have been modified by reversing the direction of the reinforcing skew angle .
C.4
Reinforcement Area Calculations
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Appendix C
Reinforcement areas are calculated using the approach described by Clark using the equations by Nielson. The full equations are extensive and complex and so only a brief overview of the method employed is given below. Full details of the procedure may be found in the document ESR170490 - ASASPOST „Reinforcement Area Calculations‟. The method assumes that the loading in a slab is carried as direct loading only in the layers of concrete at the top and bottom of the slab. The thicknesses of these layers are assumed to be twice the relevant reinforcement cover depth. The loading in the layers are calculated from the following equations:
Similar equations may be written for NyT, NyB, NxyT and NxyB equivalent forces. The actual load to be carried by the X and Y directional reinforcing is then given by:
N*x = Nx + Nxy N*y = Ny + Nxy
If N*x < 0 then :
N*y = N y +
N xy
If N*y < 0 then :
or 2
N*x = N x +
Nx
N xy
2
Ny
and N*x = 0
and N*y = 0
If N*y < 0 then N*y = 0
If N*x < 0 then N*x = 0
It will be apparent that these are effectively the same as the Wood-Armer equations above and indeed the full set for skew reinforcement applies. Having established the load carried by the reinforcing (N*) the area of required area of reinforcing is given by:
Ax =
N*x FRA
A y=
N*y FRA
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Appendix C
In addition the principal concrete compressive force fc is also calculated:
f c= -2 Nxy
If N*x < 0 then :
f c = Nx +
or
N2xy
If N*y < 0 then :
f c= N y +
Nx
N 2xy Ny
and N*y = 0
and N*x = 0 If N*x < 0 and N*y < 0 then :
f c=
Nx + Ny + 2
2
Nx-N y + N 2xy 4
The above equations do not consider any compressive load capability of the reinforcement. For details of how this effect is included see the document ESR170490 described above.
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Appendix C
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Appendix D -
Appendix D
- Loadcase Combination Methods
The stress results for new loadcases in POST may be formed by factoring the stresses from the ASAS, or previously formed new POST loadcases and combining them according to one of the following methods: SSUM
-
simple summation (default) The factored stresses for each of the constituent loadcases are simply added together.
ABSS
-
absolute sum. The absolute values of the factored stresses for each of the constituent loadcases are added together. All resulting stresses will be positive.
SRSS
-
square root of the sum of the squares The factored stresses for each of the constituent loadcases are squared and then added together. The resulting stresses are then square rooted. The final stresses will be positive.
MXLS
-
maximum limit stress The stresses for each of the constituent loadcases are examined to see if they are positive (additive) or negative (relieving). If they are additive, then they are factored by the first factor, if relieving, then they are factored by the second. The resulting factored stresses are then combined using the SSUM method.
MNLS
-
minimum limit stress The stresses for each of the constituent loadcases are examined to see if they are negative (additive) or positive (relieving). If they are additive, then they are factored by the first factor, if relieving, then they are factored by the second. The resulting factored stresses are then combined using the SSUM method.
MAXE
-
maximum envelope The factored stresses for each of the constituent loadcases are considered in turn. The final loadcase consists of the highest (positive) stress values found in the constituent loadcases for each stress type.
MINE
-
minimum envelope The factored stresses for each of the constituent loadcases are considered in turn. The final loadcase consists of the lowest (negative) stress values found in the constituent loadcases for each stress type.
MXAE
-
maximum absolute envelope The absolute values of the factored stresses for each of the constituent loadcases are enveloped using the MAXE method.
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WDME
-
Appendix D
Wood-Armer moment envelope The Wood-Armer moments are calculated from the factored stresses of each of the constituent loadcases. The resulting Wood-Armer moments are then enveloped.
REEN
-
Reinforcement Calculation Envelope The reinforcement requirements are calculated from the factored stresses of each of the constituent loadcases. The resulting reinforcement requirements are then enveloped.
For LAMI type data the loadcase combination is conducted on the composite section strains and not the individual layer stresses. The user should take this into account in the case of envelope and limit stress type combinations.
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Appendix D
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