Training material of AutoForm One Step....
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[email protected] ALGHAFORM FORUMLARI PAYLASIMIDIR
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4 AutoForm–OneStep
AutoForm–OneStep has been developed to recognize forming problems quickly and effectively at a very early stage of product development and to modify the part geometry accordingly. The flexible input in AutoForm–OneStep permits the creation of a binder surface including the punch opening line. Thus AutoForm–OneStep is suited for a simple feasibility analysis and additionally for a quick verification of a tool design and the comparison of different tool concepts. The simulation of completely designed tools can be made in extremely short calculation times. The seamless integration of AutoForm–OneStep with the AutoForm–Optimizer helps you finding optimized geometry and process parameters. The inverse formulation of AutoForm–OneStep allows for the simple and precise determination of the blank outline and thus the minimal material requirements. This opens new perspectives for quotations/estimations as well as for tool design considering the optimized blank and thus the minimal material consumption. The integration with all other AutoForm products makes many additional functions available such as AutoForm–DieDesigner or AutoForm–Optimizer for the optimization of the part geometry, binder surfaces, addenda or process parameters. AutoForm–OneStep supports five different calculation types, which require different forming knowledge of the user and are used for different tasks: Part only (1-step)
The calculation is exclusively based on the part geometry; starting from the part geometry the flat blank is calculated (inverse calculation method). The specification of the part boundary line allows for the simple modification of the part boundary. This simplest calculation type requires the least forming knowledge of the user and is especially suited for forming analyses during part design as well as for the estimation of the forming complexity of the part and for the determination of the minimal material consumption for quotation and estimation purposes. As the impact of the addendum is only considered by restraining forces on the part
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boundary, the accuracy of a Part only calculation is coarse, especially along the part boundary. This calculation type does not directly determine the flat blank but the curved blank, which in the real forming process conforms to the shape of the sheet after binder closure. The binder surface has to be defined. A two step process is simulated:
Part only (2-step)
• Friction free binder closure involving no restraining force • Deep drawing involving friction and restraining forces The remarks of the preceding paragraph obtain – indeed this calculation type provides more realistic results for parts with extremely curved binder surfaces. Since there is no real addendum involved in the calculation, it is important to have an especially realistic binder as used in the real tool. Yet it is sufficient if the surface tolerably conforms to the part contour to improve the quality of the calculated results. For this reason, this method is useful for the part designer who does not necessarily have a deep understanding of the forming process. Based on the defined binder surface and punch opening line, AutoForm–OneStep automatically generates a simple addendum, running out of the part boundary tangentially and running into the binder surface on the punch opening line tangentially. The calculation is based on the part and the addendum using the two step method. If a realistic binder surface is available, this calculation type improves the quality of the results considerably compared to the Part only calculation, because a rough geometric addendum is taken into account – the simulated process is thus closer to the real forming process.
Part+Binder (2step)
This calculation type is especially well–suited for rapid verification and comparison of different tool concepts. Since the binder essentially influences the addendum and hence the results, the user should possess the essential forming knowledge about the generation of binder surfaces. The calculation is based on the completely defined tool. The punch opening line and the flange boundary line at the end of the forming process have to be defined. These two lines determine the flange surface, on which binder pressure is applied to control material flow. The Full tool calculation type gives the most precise results of all OneStep calculation types.
Full tool (1-step)
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This approach is well–suited for the verification of tool concepts, developed e.g. in AutoForm–DieDesigner. As the blank outline after forming (OS boundary) has to be defined due to the inverse calculation method, precise minimal pre–cut parts can be determined, which can then be used as initial blank for an incremental simulation. The 1-step option of the Full tool calculation is suited for tool with plane binder surfaces. Full tool (2-step)
As for a Part only (2-step) calculation the binder surface is determined at first – binder closure is accomplished without friction and retraining forces. This calculation type is used for tools with a curved binder. As for Full tool simulations the restraining forces in the binder surfaces are of essential importance for the results, the 2-step option should be preferred – otherwise the simulation assumes that the restraining forces in the binder surface already apply for binder closure. That does not correspond to the real forming process and may lead to a significant overestimation of strains. Besides the remarks on the Full tool (1-step) calculation type obtain. The necessary geometric input data for the five simulation type are summarized in the following table: Full tool
Full tool
(2 - step)
Part + Binder (2 - step)
(1 - step)
(2 - step)
part
part
part
die
die
Binder surface
no
yes
yes
no
yes
OS boundary
pb line
pb line
f line
f line
f line
OS punch opening
no
no
yes
yes
yes
Part only
Part only
(1 - step)
Part/Tool geometry
Legend: pb line = part boundary line f line = flange line www.alghaform.com
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AutoForm offers a geometry module named AutoForm–PartDesigner for the advanced use of AutoForm–OneStep in feasibility analyses during part design. It makes possible the optimization of forming parameters in the most important geometric modifications of the part in AutoForm: • Automatic generation of variable fillets on the product geometry • Rapid determination of the best fillet radius for forming • Determination of the die tip (drawing direction) • Automatic geometry creation to fill designed holes • Boundary fill by filling concave inlets: The accuracy and usability of the Part only results increase significantly in the outer boundary area of the part. • Modification of geometry regions by cutting and controlled filling • Overcrowning of entire part regions • Automatic and interactive development of binder surfaces: The accuracy of the simulation increases significantly for the Part only (2-step) calculation type. • Fully parametrized treatment of input data to facilitate the optimization with AutoForm–Optimizer • AutoForm–OneStep provides five different simulation types. For certain functions described in this workshop the AutoForm– PartDesigner must be available. The respective functions are marked. One of the most important features of AutoForm–OneStep Version. 3.1 is the greatly improved user–friendliness and the ease with which the simulations are set up, run and evaluated. The Onestep wizard has been developed for the Part only simulation. This wizard makes it possible to run feasibility studies quickly and reliably considering different process parameters in a single simulation
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Contents of the Workshop „AutoForm–OneStep“ Lesson 1
Part only Simulation with OneStep Wizard . . . . . . . . . . . . . . . . 6 • • • •
Lesson 2
Part only (2-step) Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . 21 • • • •
Lesson 3
Importing CAD data Determining the drawing direction Defining holding conditions Evaluating the OneStep simulation
Variable Restraining Option Preparing the geometry Part boundary Binder surfaces
Part + Binder (2-step) Simulation Simulation.. . . . . . . . . . . . . . . . . . . . . . . 37 • Filling holes • Boundary fill • Automatic binder generation (Auto Binder)
Lesson 4
Full tool (1-step) Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 • • • • •
Lesson 5
Full tool (2-step) Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 • • • •
Lesson 6
Full tool Tailored blank Linear weld line Material mark Material lines
Drawbead Symmetry Optimizing the blank Importing and exporting lines
Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 • • • • •
Numerical optimization Parameter study Optimization of the force factor Optimization of the force factor of a drawbead Evaluating the optimization 5
Lesson 1: Part only Simulation with OneStep Wizard
4. 1 Lesson 1: Part only Simulation with OneStep Wizard This lesson presents a simple example for AutoForm–OneStep. Using AutoForm– OneStep is it possible to run a feasibility analysis for the part geometry in a fast and straightforward manner. Fig. 1.1
Geometry for the OneStep simulation
Setting up the Simulation File At the start of the OneStep simulation, you have to define the simulation file (*.sim). This simulation file contains all the information about the calculation (geometric input, process parameters, numerical values ...) and finally the results of the computation. Set up the simulation file using the following command: File > New onestep ... The window OneStep wizard (for a OneStep–Part only simulation) opens (Fig. 1.2):
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Lesson 1: Part only Simulation with OneStep Wizard
Fig. 1.2
OneStep wizard
Importing the Part Geometry The geometry import is carried out using the module afmesh, the integrated IGES–/VDAFS interface, which automatically meshes the part geometry. The part geometry needs to be available as surface model containing the inner or outer side of the part geometry. The following formats are supported for import: af, afb (binary Autoform–Format), Nastran, Dyna and Stl. For this lesson a VDAFS file is available. Import this file: OneStep wizard
Import ... > VDAFS > OK > Files: os_lesson_01.vda > OK > afmesh_3.1 > OK
Fig. 1.3
Import geometry
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Lesson 1: Part only Simulation with OneStep Wizard Fig. 1.4
Afmesh Options for meshing the CAD data • Error tolerance: Allowable chordal error tolerance for the meshing. Value is taken from New file dialog (Default: 0.1) (Fig 1.1), but it can be changed. For especially small radii (equal or lesser than 2 mm) 0.05 should be used as error tolerance. • Max side length: Maximum element side length. Default setting: 50.
Parameters
• Treat only: Only specified faces will be meshed. Possible entries are e.g. 1, 2, 6-8. • Exclude: The specified faces are not taken into account for meshing. Possible entries are e.g. 1, 2, 7-9.
Faces
• Treat only (for IGES import only): Only specified layers will be meshed. • Exclude (for IGES import only): The specified layers are not taken into account for meshing.
Layers
The meshed part geometry is immediately displayed in the main display.
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Lesson 1: Part only Simulation with OneStep Wizard
Fig. 1.5
OneStep wizard Enter a project identifier into the field Title of the OneStep wizard. This identifier will be always be indicated in the bottom of the user interface. Note: Note A title is automatically suggested including the current file name, the user name and the date of creation. OneStep wizard
Title: lesson_01 The following three areas of the OneStep wizard have to be specified to prepare the simulation: • Geometry • Blank • Process
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Lesson 1: Part only Simulation with OneStep Wizard First, the part geometry has to be rotated such that the drawing direction corresponds to the z–axis and no backdrafts occur in the part. Use the buttons in the field Tip. Checking for Undercuts Click the Backdrafts button in field Display. Geometry > Display > Backdrafts Faces containing undercuts will be displayed red in the main display (Fig. 1.6) The meaning of the colors: • Safe (green): Backdraft angle greater than 3 degrees • Marginal (yellow): Backdraft angle between 0 and 3 degrees • Severe (red): Areas containing undercuts smaller than 0 degree The part contains undercuts, thus it has to be tipped into drawing direction. To determine a proper drawing direction we recommend using the automatic function Min backdraft: Geometry > Tip > Min backdraft This function calculates a drawing direction with minimum undercuts. Fig. 1.6
Backdrafts: Backdrafts Representation of areas containing undercuts www.forum.alghaform.com
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Lesson 1: Part only Simulation with OneStep Wizard
The part contains no undercuts in the calculated drawing direction (Fig. 1.7). In case the tipping direction calculated with the automatic functions do not result in an acceptable drawing direction, use the manual functions (Tip: x-axis/y-axis) to modify the drawing direction. Fig. 1.7
Undercut free part geometry Having tipped the part geometry, you can now apply filleting in the areas containing sharp edges globally and fill the part boundary. Adjust the representation in the main display as follows: Geometry > Display > Faces Global Filleting of all sharp edges in the part geometry Use the following command to fillet sharp edges: Geometry > Fillet > Radius: 3 Filling the Part boundary Generate the boundary fill now. Fill areas are created automatically along the part boundary. The outer boundary fill line is determined by a roll cylinder moving around the part boundary and its roll radius: Geometry > Boundary fill > Roll radius: 100.00
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Lesson 1: Part only Simulation with OneStep Wizard To start the global filleting and the creation of the boundary fill and the generation of the resulting part boundary, click Apply The resulting geometry containing the generated part boundary is shown in Fig. 1.8. The part boundary has changed during the creation of the boundary fill (see also Fig. 1.9 and Fig. 1.10). Fig. 1.8
The resulting geometry and the part boundary Fig. 1.9
Detail: Detail Part boundary – before boundary fill
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Lesson 1: Part only Simulation with OneStep Wizard
Fig. 1.10
Detail: Detail Part boundary – after boundary fill The geometry has been completely prepared for the simulation. Define the sheet thickness and select a material: Defining Material Properties Blank > Thickness: 1 Blank > Material > Import ... > Select material > zste180bhZ_1.mat > OK Define the restraining forces on the part boundary in the area Process. Different holding conditions can be used. The holding condition Free corresponds to ideal deep drawing, e.g. for tools without a binder. In contrast the holding condition Locked corresponds to stretch forming, e.g. for tools with extremely high binder pressure. Restraining forces, corresponding to a usual tool in which material draw–in occurs, can be defined by means of weak, medium, strong and User defined. The current simulation will be calculated using standard settings (Free, Medium and Locked). The complete input for the simulation is shown in Fig. 1.11.
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Lesson 1: Part only Simulation with OneStep Wizard Fig. 1.11
OneStep wizard: Part only simulation wizard Prepared OneStep–Part Store the prepared simulation and start the simulation: File > Save as ... > os_lesson_01.sim > OK Start ... > Program: afos_3.1 > Start Note: Note The OneStep wizard contains a number of selected functions for the definition of the simulation. Use the Advanced ... button to access additional functions in AutoForm–OneStep. These additional functions will be described in the following lessons.
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Lesson 1: Part only Simulation with OneStep Wizard
Evaluating Simulation Results The following section describes the most important result variables of a OneStep simulation. Having completed the calculation of the simulation, re–open the SIM file using the command: User interface
File > Reopen The main display shows the calculated part geometry. In the lower part of the user interface, three buttons are available: free, medium and locked. Click one of the buttons to load the results for the respective holding condition from the SIM file. Compare the results.
Fig. 1.12
The user interface after loading the calculated simulation Formability The result variable Formability gives you a general survey of the feasibility of the part. Areas undergoing different stresses are colored differently on the part: • Cracks (red): Areas of cracks. These areas are above the FLC of the specified material. • Excess. Thinning (orange): In these areas, thinning is greater than the acceptable value (default value for steel is 30%).
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Lesson 1: Part only Simulation with OneStep Wizard • Risk of cracks (yellow): These areas may crack or split. By default, this area is in between the FLC and 20% below the FLC. • Safe (green): All areas that have no formability problems. • Insuff. Stretching (gray): Areas that have not enough strain (default 2%) • Wrinkling tendency (blue): Areas where wrinkles might appear. In these areas, the material has compressive stresses but no compressive strains • Wrinkles (purple): Areas where wrinkles can be expected, depending on geometry curvature, thickness and tool contact. Material in these areas has compressive strains which means the material becomes thicker during the forming process. Select the result variable Formability. Compare the results for the different restraining forces. The results for the holding condition • free is shown in Fig. 1.13, • medium is shown in Fig. 1.14 and • locked is shown in Fig. 1.15. Fig. 1.13
Formability with holding condition free
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Lesson 1: Part only Simulation with OneStep Wizard
Fig. 1.14
Formability with holding condition medium Fig. 1.15
Formability with holding condition locked
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Lesson 1: Part only Simulation with OneStep Wizard You can see from the figure that the part is insufficiently stretched, using the holding conditions free and medium. There are several areas containing wrinkles (purple), wrinkling tendencies (blue) and insufficient stretching (gray). Using the holding condition locked, the part is sufficiently stretched. A small area of insufficient stretching (gray) can be seen on the left end (Fig. 1.15). Thinning Switch to the result variable Thinning (second row of icon panel in main display, middle button). A scale is displayed in the lower part of the main display with a range of 30% thinning to 3% thickening (depending on the specified color settings) (Fig. 1.16). Fig. 1.16
Thinning (in percentage) with the holding condition locked The exact thinning value (in percentage) is displayed, when you click with the right mouse button on the geometry. Hit the Esc key to clear these labels from the display. To find the maximum thinning and the maximum thickening of the part use the following options Results > Show max Results > Show min
User interface
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Lesson 1: Part only Simulation with OneStep Wizard
Close AutoForm–User Interface The user interface can be closed with following option: File > Quit or hotkey Ctrl – Q.
The area Geometry (OneStep wizard) Use the functions of this area to check if the meshed part geometry is suitable for the simulation (undercuts and sharp edges) and to prepare the geometry for the simulation. The following functions are available: • Symmetry: Define the symmetry plane for symmetrical parts. This definition is possible for the values X = 0, Y = 0 or no symmetry. • Tip: Determines the drawing direction of the part. • Min backdraft: Calculates a drawing direction with minimum undercuts. • Screen axes: Uses the normal of the display as drawing direction. • Reset: Uses the original axis of CAD data (z–axis) as drawing direction. • X- and Y-axis: Allows for the manual rotation by a defined angle about the x– or y–axis. • Del picked: Removes selected faces from the meshed geometry. • Del backdraft: Removes faces containing undercuts from the geometry. • Undel picked: Deleted faces are restored. • Undel all: All deleted faces are restored. • Display: Switch for the representation • Faces: Each face is represented by another color. • Objects: The geometry is represented by a single color. • Backdraft: The geometry is automatically checked for faces containing undercuts. The faces are colored green for safe areas, yellow for areas with marginal undercuts and red for areas containing severe undercuts. • Deleted: Deleted faces are displayed again. • Part boundary: The part boundary needed for the simulation is generated. • Error tolerance: Acceptable chordal error for the part boundary. The value can be changed. For especially small radii (equal or lesser than 2 mm) 0.05 should be used as error tolerance.
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Lesson 1: Part only Simulation with OneStep Wizard • Fillet: The geometry is checked for sharp edges. The sharp edges are filleted by the defined radius automatically (Radius:). • Boundary fill: Holes are filled and the boundary fill is created (Roll radius:). • Apply: Use the Apply button to execute all functions defined.
The area Blank • • • • •
Thickness: Sheet thickness Material: Material Import ...: Import a material from the material database View ...: Shows the current material properties Input ...: Defining material properties
The area Process Use the functions of this area to define the restraining forces (Holding conditions). The following holding conditions are available: • • • • •
Free: No restraining forces (ideal deep drawing) Weak (0.15): Weak restraining forces Medium (0.35): Medium restraining forces Strong (0.9): Strong restraining forces Locked: Locked (stretch forming)
Besides the above conditions, it is also possible to enter freely defined values (User def.). Decide which of the holding conditions will be used for the simulation. Click All to use all holding conditions, click None to use no holding condition. The simulation is calculated separately for each of the defined holding conditions. By default the three holding conditions (Free, Medium and Locked) are set. In version 3.1, all OneStep results are stored in a single SIM file thus eliminating the need for manual iterations with different conditions being stored in separate files.
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Lesson 2: Part only (2-step) Simulation
4. 2 Lesson 2: Part only (2-step) Simulation The functions introduced in this lesson make possible the more precise definition of restraining forces in AutoForm–OneStep. Besides the Part only (2-step) simulation calculates the developed blank more precisely. This simulation type requires the definition of a binder surface in addition to the inputs required for a Part only (1-step) simulation. This simulation proceeds in two steps: • Simulation, in reverse, of the drawing process from binderwrap to the final product geometry. The reverse process takes into account friction as well as the restraints applied to the OS boundary, and establishes the outline of the developed blank mapped on to the geometry of the curved binder surface. • Simulation, in reverse, of the binderwrap process. During this process, no restraints are applied on the sheet, and the developed blank outline is unfolded from the curved binder surface on to the flat surface. The above 2–step approach is more representative, particularly in the case of curved and deep–drawn parts, of the actual stamping process. Therefore, results of 2–step simulations are more accurate for these parts, and are closer to those of an incremental process simulation. Fig. 2.1
Cross member geometry including the binder surface User interface
Setting up a new Onestep Simulation File > New onestep … to open the OneStep wizard.
Importing and Editing the CAD geometry Use the following commands to import the CAD data: OneStep wizard
Import ... > VDAFS > OK > os_lesson_02.vda > OK > Program: afmesh_3.1 > OK 21
Lesson 2: Part only (2-step) Simulation The crossmember geometry is displayed in the main display, and the OneStep wizard is filled with a few default values.
Editing Parts Faces There is an upstanding flange around one of the holes of this part. If this flange were to remain on the part geometry during simulation, a prediction of cracks would result at the flange. However, since these flanges would be formed in a secondary operation, they may be ignored in the OneStep simulation without any errors, and may therefore be eliminated as follows: Hold the Shift key down and use the right mouse button to pick the flange faces. Click the Del picked button to remove the faces from the geometry. The remaining faces form the part, i.e. it is only these faces that are taken into account during subsequent simulation. Fig. 2.2
Selected flange faces for deletion Del picked deletes selected faces.
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Lesson 2: Part only (2-step) Simulation
Fig. 2.3
Representation of deleted faces The deleted faces are represented as a mesh. Select the faces and subsequently use the buttons Undel picked or Undel all to add the faces back to the part again.
Establishing the Drawing Direction In preparation for a simulation, the imported product geometry needs to be rotated so that the drawing direction for the product is parallel to the z–axis: There should be no backdraft faces on the geometry relative to the z–direction. There are several manual or automatic options that you may apply to establish the required die tip. The ideal die tip may be established in the present case using the Min Backdraft option: Display: Backdrafts shows backdrafts on the geometry. Tip: Min backdraft re–orients the product geometry such that the product faces, on average, have the largest possible inclination to the z–direction.
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Lesson 2: Part only (2-step) Simulation Fig. 2.4
Re–oriented geometry with representation of backdrafts
Generating the Part Boundary (Outer boundary of the product geometry) After editing the product geometry, the boundary of the current geometry may be generated automatically by clicking the Apply button. Display: Objects shows the geometry in colored and shaded mode. Apply in the field Geometry generates the part boundary.
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Lesson 2: Part only (2-step) Simulation
Fig. 2.5
Geometry with part boundary
Defining the Material Properties The default material selection is FeP04; an alternate material file may be selected from the extensive material library using the Import ... button. Blank: Import ... to open the dialog Select material. Use the buttons View or Preview to display the properties of the selected material: Hardening curve, forming limit curve and r–values. Fig. 2.6
Select material / Preview 25
Lesson 2: Part only (2-step) Simulation Files: zste220P_1.mat > OK
The Advanced Mode All necessary information has been entered into the OneStep wizard. The settings in the area Process are left unchanged. Fig. 2.7
OneStep wizard containing all information Additional information is entered in the Advanced mode. Click OneStep wizard
Advanced ... The dialog AutoForm - Question pops up:
Fig. 2.8
AutoForm - Question Finish closes OneStep wizard and opens AFOS input generator. www.forum.alghaform.com
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Lesson 2: Part only (2-step) Simulation
Fig. 2.9
AFOS Input generator The full function range of the AFOS input generator will be described in one of the following lessons. For this example only the pages Geometry and Process are used. For the following steps, we require a license for AutoForm–PartDesigner.
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Lesson 2: Part only (2-step) Simulation
Preparing a Binder Surface Open the Geometry generator. Model > Geometry generator ...
User interface
Generate a binder on the Binder page.
Binder Fig. 2.10
Geometry generator: Binder page Auto > Apply (Leave the default settings unchanged)
Binder
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Lesson 2: Part only (2-step) Simulation
A log window pops up containing information on the progress of the binder surface calculation. Fig. 2.11
Log window The product geometry and a curved binder are shown in the main display. Fig. 2.12
Product geometry with binder
Selecting the Geometry Type Select the geometry type Part only (2-step) on the Geometry page of the Input generator. Part only (2-step)
Geometry
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Lesson 2: Part only (2-step) Simulation Fig. 2.13
Geometry Type Part only (2-step) In addition to the product geometry there is a binder surface now. The OS boundary has been copied depending on the part boundary.
Variable Restraining Options In a lot of cases, a constant magnitude of restraining force applied to the OS boundary in a Part only simulation does not lead to optimal predictions of product quality. For example, localized areas may be insufficiently stretched, or may have very large strains close to or exceeding the forming limit (leading to a prediction of cracks). In such cases, it would be useful to vary the holding conditions around the OS boundary to achieve optimal stretch conditions over the entire product geometry without causing splits, cracks or excessive thinning. Medium > Restraining options > Variable Enter the restr into the field Name:
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Process
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Lesson 2: Part only (2-step) Simulation
Holding condition > Name: restr Fig. 2.14
Restraining options Variable Before selecting nodes along the part boundary using the function Input points ..., we recommend to adjust the view from z–direction. User interface
View > From +Z (yx) and View > Fit to window This can also be done using the keyboard by pressing Ctrl – Z for the view orientation followed by Ctrl – W to fit to window.
Input generator
restr > Input points … The dialog for the definition of nodes opens:
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Lesson 2: Part only (2-step) Simulation Fig. 2.15 a
Definition of restraining forces Add/edit point Fig. 2.15 b
Definition of the force factor In the main display many nodes are shown along the part boundary. Select any of these nodes using the right mouse button and define a specific restraining force factor value at each of the selected nodes. OK to finish the definition of nodes. The actual restraining force variation over a segment is interpolated linearly between values set at the nodes bounding this segment.
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Lesson 2: Part only (2-step) Simulation
The figure below shows a total of 15 restraining point defined over the OS boundary of the cross member geometry. Fig. 2.16
15 nodes with different force–factors Fig. 2.17
Variable restraining forces User interface
Evaluation of the results File > Save as > os_lesson_03.sim to save the input data. Job > Start simulation ... > Start to start the calculation. File > Reopen reads the results. To review the results for the variable restraining forces, click the button restr at the bottom of the AutoForm–User Interface. restr
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Lesson 2: Part only (2-step) Simulation Click the button for the result variable Formability:
Fig. 2.18
Formability with variable restraining forces Besides the representation of the part with the result variable and the developed blank the representation of the binderwrap is available now. Use the three buttons on the lower left side of the AutoForm–User Interface to select the desired representation.
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Lesson 2: Part only (2-step) Simulation
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shows the binder-wrap. Fig. 2.19
Binderwrap
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Lesson 2: Part only (2-step) Simulation shows the developed blank. Fig. 2.20
Developed blank
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Lesson 3: Part + Binder (2-step) Simulation
4. 3 Lesson 3: Part + Binder (2-step) Simulation This simulation type is useful in the initial phase of methods and process planning when only the part geometry is available. By enabling quick and interactive generation of binder surfaces based on product geometry, and by allowing the binder surface to be used in the simulation, it becomes possible to assess the influence of these tool surfaces on feasibility, and possibly to optimize these and associated process parameters in conjunction with product geometry in early stages itself. Fig. 3.1
Part geometry The procedure in creating and defining inputs and in running simulations of this type is as follows: User interface
File > New > File name: lesson_os3 Units: mm and N Geometric error tolerance: 0.1 > OK
Geometry generator
File > Import > VDAFS > OK > File: lesson_os3.vda > OK
Prepare
Symmetry / double… > x-z-plane y: 0 > OK > Apply
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Lesson 3: Part + Binder (2-step) Simulation Fig. 3.2
Sharp Edges Go to the Fillet page to determine the sharp edges of the geometry. Check radius: 2.00 > Check > OK
Fillet
The areas on the part containing sharp edges are displayed. Fig. 3.3
Areas containing sharp edges Areas in the part containing sharp edges are displayed. It is necessary to fillet all sharp edged areas in the part. There are two ways to fillet sharp edges: Globally with a global fillet radius or locally with 38
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Lesson 3: Part + Binder (2-step) Simulation
a constant or variable radius or radius transition. We will describe all these variants. Global Filleting Global fillet radius: 3.00 > Apply All areas containing sharp edges will be filleted using a radius of 3 mm. Local Filleting by a Constant Radius (requires AutoForm–PartDesigner license) In order to generate variable radii at individual edges, the edges need to be identified and the radii need to be specified. Click the Add line ... button at the bottom of the Fillet page to identify sharp edges. Add line ... opens the window containing the message: Mark radius control edge. Finish with double click. Selecting an edge also involves identifying the length along the edge that will be filleted. Edges have to selected one after the other, each time clicking the Add line ... button to start a new selection. Fig. 3.4
Local filleting
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Lesson 3: Part + Binder (2-step) Simulation Click once with the right mouse button to select the starting point at an edge of interest, let go the mouse button and move your mouse cursor along the curved outline of the edge. This progressively highlights (in yellow) the length of the edge. Double click the right mouse button to end the edge selection. Note: Note If the run of the curve representing the edge is ambiguous (long, extremely curved edge or branchings along the curve), set intermediate points to define the run of the curve precisely. Click the right mouse button repeatedly along the curve representing the edge. Add line ...
Fillet
Mark the entire curve, as shown in Fig. 3.4. line1: > Constant > Constant fillet radius: 5.00 > Apply Local Filleting by a Variable Radius (requires AutoForm–PartDesigner license) To generate variable fillets, the edges to be filleted need to be selected as described above. Subsequently, „radius control“ points are selected on each of these edges, and radius values are specified at each of these points. Add line ... > line2: > Variable > Selecting 4 radius control points > OK
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Fillet
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Lesson 3: Part + Binder (2-step) Simulation
Fig. 3.5
Locally filleted edges Fillet
Assign a radius to each of the control points. Finally click the button Apply
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Lesson 3: Part + Binder (2-step) Simulation The Fillet page is as shown in Fig. 3.6: Fig. 3.6
Fillet page
Definition of Drawing Direction It is necessary to rotate the imported geometry from vehicle to draw position in order to eliminate backdraft conditions.
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Tip
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Lesson 3: Part + Binder (2-step) Simulation
Fig. 3.7
Backdraft faces on the part geometry Incremental tipping > Y-axis > by degrees: 45 > rotate: The part is now free of undercuts. Modify P page (requires AutoForm–PartDesigner license) Use the functions of the Modify P page to fill holes contained within the part geometry. Modify P
All holes > Define holes > Min size: 1.50 > Max size: 300.00 > Apply Use the functions of the Bndry page to fill of areas on the part boundary:
Bndry
Add Bndr fill ... > Curve 1 > OK > Fill parameters: Bndry fill roll radius: 300 > Apply Note: Note Smoothening the part boundary increases the accuracy of the simulation results on the part boundary, especially for concave regions.
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Lesson 3: Part + Binder (2-step) Simulation Fig. 3.8
Filling holes and boundary fill Generate the binder surface on the Binder page using the AutoBinder function (requires AutoForm–PartDesigner). Auto For the binder a minimum drawing depth is required. Drawing depth: Minimum The main curvature direction of the binder is defined in y–direction, i.e. by an angle of 90°. Profile orientation > Angle: 90 deg
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Binder
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Lesson 3: Part + Binder (2-step) Simulation
Fig. 3.9
Auto Binder page Binder
Apply A curved binder surface has been generated. Analyze the distance between the binder and the part in the AutoForm–User Interface. Adjust the value range of the result scale for the current example: Geometry generator > Display > Ranges > Min/Max Simulation
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Lesson 3: Part + Binder (2-step) Simulation Fig. 3.10
Plot of the drawing depth distribution on the part geometry Fig. 3.11
Adjusting display range Click any area of the part with the right mouse button to display the actual drawing depth value. Change the distance between binder and part using the function Binder position Shift. The preparation of the part geometry has been finished for the simulation. Define the process parameters in the Input generator: Model > Input generator > Simulation type: OneStep > OK
User interface
AFOS input generator Enter the title of the simulation. Enter further information on the current simulation into the field Comment.
Title
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Geometry
Lesson 3: Part + Binder (2-step) Simulation
Type: Part+binder (2-step) > Delete the current OS boundary line? > Delete
Fig. 3.12
Geometry type: Part + Binder (2-step) The definitions of part and binder geometries have been automatically accomplished by transferring data of the imported part geometry and generated binder surface from the Geometry generator. The sheet thickness for the part is 1.2 mm. By specifying an offset of 0.6 mm (Upwards), the simulation may be carried out on the midsurface of the product geometry – an Upwards offset is used since the imported surface represents the lower surface of the product. Geometry
Part > Offset: 0.6 Definition of the Punch Opening Line The punch opening line is used to define areas in which the generated mesh for the addendum has a tangential transition to the binder.
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Lesson 3: Part + Binder (2-step) Simulation OS punch opening line Dependent ... > Bndry (Bndry) > OK The Bndry (Bndry) line defines the part boundary including the outer boundary fill areas. It has to be adapted using the functions Expand and Smooth of the Curve editor. The adapted line will be used as punch opening line. Fig. 3.13
Select Curve dialog OS punch opening > Edit ... > Expand: 15 > Smooth: 0.05 > OK Fig. 3.14
Curve editor: editor OS–PO line The same approach – using the geometry of the Bndry (Bndry) line as the starting point for defining another line may be employed to accomplish the definition of the OS boundary line. This line represents the outer edge of the formed sheet at the end of the forming/ drawing process. Starting from the geometry of the Bndry (Bndry) line, Expand and Smooth options may be used to define the OS
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Lesson 3: Part + Binder (2-step) Simulation
boundary line, making sure to differentiate it from the previously defined OS punch opening line. OS boundary > Dependent ... > Bndry (Bndry) > OK Edit ... > Expand: 90 > OK > Smooth: 0.1 > OK Fig. 3.15
OS PO–line and OS boundary Blank
Thickness: 1.2 > Material: zste340_3
Fig. 3.16
Blank page Lube
Definition of Friction Lubrication > Constant > Standard 0.15
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Lesson 3: Part + Binder (2-step) Simulation Fig. 3.17
Process page
Definition of the Process Parameters Holding Conditions > Type: Binder pressure
Process
Pressure options > Pressure: 6 (default) Note: Note The binder pressure is defined relative to the final flange area. Thus a higher pressure has to be defined than for an incremental simulation, for which the pressure is defined with respect to the initial flange area. Accuracy > Mesh: Standard Starting the Simulation Job > Start simulation ... > Save > Start
Evaluating the simulation File > Reopen
Control AFOS input generator User interface
As a result of the simulation you can evaluate three different phases. Developed blank The outline of the developed blank is computed during the simulation. The edge of this blank may be exported in af, IGES or VDAFS format, and may be used to define the blank in an AutoForm–Incremental simulation. Blank outline may be exported as follows: File > Export boundaries > ...
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User interface
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Lesson 3: Part + Binder (2-step) Simulation
Fig. 3.18
Developed blank Binderwrap The result of the OneStep calculation is iterated in the binder surface considering friction. Particular high strains are thus avoided for highly curved binders.
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Lesson 3: Part + Binder (2-step) Simulation Fig. 3.19
Binder wrap Formed sheet AutoForm–OneStep offers among others the following results: • Distribution of strain and all dependent variables such as sheet thickness, failure, wrinkling, hardening, forming limit analysis and stress • Binder pressure distribution in the flange area • Distribution of sheet reaction stress • Friction shear stress • Formability etc.
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Lesson 3: Part + Binder (2-step) Simulation
Fig. 3.20
Formed sheet: Formability In the example a review of the so–called Formability map of the simulation geometry reveals a large region to be insufficiently stretched. Do as follows to improve the predictions of uniform stretching: Modify the binder pressure value to 10 N/mm², a value suitable for the higher thickness (1.2 mm) and higher strength sheet material. After modifying the simulation input data, save these to a new simulation file, run the simulation and review the results.
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Lesson 4: Full tool (1-Step) Simulation
4. 4 Lesson 4: Full tool (1-Step) Simulation This lesson describes a OneStep simulation based on a tool geometry with a tailored blank. In addition, that the weld line position is optimized in such a way that the original blank contains a linear weld line – thus reducing costs for the blank. Fig. 4.1
Tool geometry
Setting up a new Simulation File > New … > File name: os_lesson_4 > Length: mm > Force: N > Geometric error tolerance: 0.1
User interface
File > Import... > VDAFS > OK > Files: os_lesson_4.vda > OK
Geometry generator
Error tolerance: 0.1 > Max side length: 50 > OK
AF–Mesh window
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Lesson 4: Full tool (1-Step) Simulation
Definition of the Binder The meshed tool geometry is shown in the main display. Use the right mouse button to click on the binder surface of the tool geometry. The selected surface is highlighted in yellow. Click on the Binder button on the Prepare page of the Geometry generator to save these faces in the Binder register. Fig. 4.2
Selecting the binder surface
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Lesson 4: Full tool (1-Step) Simulation
Calculation of the Part boundary Part boundary generation > Error tolerance: 0.1 > Concatenation distance: 30.00
Prepare
To confirm the above selection, click on the button Apply Fig. 4.3
Geometry generator: Prepare page
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Lesson 4: Full tool (1-Step) Simulation
The part boundary of the remaining tool geometry (without binder) is shown as a blue line in the main display. Fig. 4.4
Representation of the part boundary User interface
Model > Input generator ... > Simulation type: OneStep > OK AFOS Input generator Geometry > Type > Full tool (1-Step) The pre–defined OS boundary has to be deleted. Delete > Autoform - Question: Delete the current OS boundary line? > Delete Tool The surfaces saved in the Part and the Binder registers are used to automatically define the tool geometry. Definition of the OS boundary This line represents the outer edge of the stamped part. Again, this may be defined as dependent upon the punch opening line. Dependent ... > Bndry (Pre) 1 > OK > Edit … > Curve editor > Global mod > Expand: 40 > OK
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Lesson 4: Full tool (1-Step) Simulation Definition of the OS punch opening The punch opening line may be defined as dependent upon as part boundary. Dependent ... > Bndry (Pre) 1 > OK Fig. 4.5
AFOS Input generator: Geometry page
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Lesson 4: Full tool (1-Step) Simulation
Fig. 4.6
OS boundary and OS punch opening Blank
Define the sheet thickness: Thickness: 1.0 Select the following material: Material: Import... > Steel_General+Europe: if18_1.mat > OK Define the weld line now: Add weld... > Weld line > Input ...
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Lesson 4: Full tool (1-Step) Simulation Fig. 4.7
Weld dialog The Curve editor is opened. Define the weld line by entering two points (x = 0/0, y = 200/-200). The start and end point of the weld line are positioned on the OS boundary. Note: Note To create a vertical line, press the Shift key when setting the end point of the weld line. Fig. 4.8
Definition of the weld line position Following the definition of the weld line, specify a new sheet thickness value, and then select the side of the defined weld line where the new thickness value applies (Weld dialog): Thickness: 1.5 Properties apply at > Click 60
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Lesson 4: Full tool (1-Step) Simulation
Fig. 4.9
Definition of area in the sheet with changed material properties Using the right mouse button, click at the right side of the weld line to which the new thickness will apply. Finalize the weld line definition in the Weld dialog by clicking on OK Lube
Lubrication > Constant > Constant > Standard: 0.15
Process
As you are preparing a Full tool OneStep simulation, it makes sense to define a binder pressure or binder force. Holding condition > Type: > Binder pressure > Pressure: 6 > Binder stiffness: 50
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Lesson 4: Full tool (1-Step) Simulation Fig. 4.10
Process page Leave the default settings on the Control page unchanged and start the simulation in the AFOS input generator. Job > Start simulation ... > Save > Start job: Start After simulation is completed, the results may be viewed and evaluated in the AutoForm–User Interface by reopening the simulation file: File > Reopen
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User interface
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Lesson 4: Full tool (1-Step) Simulation
Select the result variable Thickness.
Fig. 4.11
Distribution of thickness
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Lesson 4: Full tool (1-Step) Simulation Click on the button for the developed blank
: Fig. 4.12
Developed blank You realize that the original linear weld line has moved during the forming process. It is the objective now to keep the weld line position as it is and to optimize the weld line position in such a way that the original blank can be formed with a linear weld line. To achieve the objective, define material marks at both ends of the weld line on the developed blank. Results > Material marks ... > Set marks
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User interface
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Lesson 4: Full tool (1-Step) Simulation
Fig. 4.13
Coordinates of the material marks Define the two material marks as material line. Internally additional material marks are added along the material line. AutoForm - Material marks > Define > Material line Click on the button Formed Sheet in the lower left area of the AutoForm–User Interface and display the originally defined weld line. Display > Lines ... > Weld 1 > Dismiss You can judge from the material lines if the warped position within the part is still acceptable and if the weld line is still in the correct position.
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Lesson 4: Full tool (1-Step) Simulation Fig. 4.14
Different weld line positions Use the material line on the formed part as weld line for another simulation. For this purpose export the material line: Results > Material lines ... > Material line 1 > File > Write selected to file … > AF Poly3D > CLOSED polylines: No > weldnew.af > OK > Material lines > File > Dismiss
User interface
Save the simulation under another name: File > Save as > os_lesson_4b.sim > OK Open the AFOS Input generator again. Model > Input generator ... Edit the weld line position on the Blank page by importing the stored material line as new weld line. Symmetry-planes/welds/holes > Edit ... > Import ... > Delete > Format: af > OK > weldnew.af > OK > curve 1 > OK > OK
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User interface
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Lesson 4: Full tool (1-Step) Simulation
Start the simulation and check whether a linear weld line is available in the developed blank. Fig. 4.15
Optimized weld line on the developed blank
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Lesson 5: Full tool (2-step) Simulation
4. 5 Lesson 5: Full tool (2-step) Simulation This lesson is based on a prepared simulation file. The tool contained in this file has been generated with AutoForm–DieDesigner. Objective of this lesson is the definition of symmetry conditions and drawbeads. In addition, we will also show how to optimize the initial blank. Fig. 5.1
Tool geometry
Opening the prepared Simulation File Open the prepared simulation file in the AutoForm–User Interface: File > Open ... > Select a file: os_lesson_05.sim > OK The AFOS input generator is opened automatically. Because the Geometry page is shown in red, you have to enter more information on the Geometry page. The following settings have already been defined: Full tool (2-step) simulation with tools and binder surface. Define the OS boundary by importing an existing line in AutoForm format (.af).
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Lesson 5: Full tool (2-step) Simulation
Fig. 5.2
AFOS Input generator: Geometry page Geometry
Import OS boundary OS boundary > Import ... > Format: af > Vertices: use all rotate > OK > Select a file: osboundary05.af > OK > Select curve: Curve 1 > OK Define the OS punch opening line now. This line is defined as dependent on the punch opening line as specified in the DieDesigner tool geometry.
Geometry
OS punch opening OS punch opening > Dependent ... > Select curve: Punch opening 1 > OK
Symmetry Define the symmetry–plane on the Blank page. The sheet thickness and the material properties have already been specified.
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Lesson 5: Full tool (2-step) Simulation Symmetry-planes/welds/holes: Add symmetry ... > Symmetryplane: Click segment > User interface: Click the OS boundary at the symmetry-plane > Symmetry-plane: OK
Blank
Fig. 5.3
Symmetry plane
Defining Drawbeads Drawbeads may be modeled in AutoForm using a force factor to control metal flow, without having to build the detailed drawbead geometry into the CAD model of the tool. This gives the user flexibility in using AutoForm as a tryout tool – using it to quickly compare the performance of different drawbeads vis–a–vis feasibility requirements, and to identify the best bead configuration, based on comparisons, without having to modify tool geometry to accomplish the same. AFOS input generator Add > Drawbead > Add drawbead: Use default settings > Add drawbead A Drawbead (Drwbds) page is added to the AFOS input generator. Define the position of the drawbead:
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Lesson 5: Full tool (2-step) Simulation
Fig. 5.4
AFOS Input generator: Drawbead page Drwbds
Drawbead line > Input ... > Curve editor Move the mouse cursor into the main display. Using the right mouse button, click three points on the geometry to create the drawbead (see Fig. 5.5). End input of the drawbead by double click and finally close the Curve editor by clicking Curve editor > OK
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Lesson 5: Full tool (2-step) Simulation Fig. 5.5
Position of the drawbead Functions for generating a drawbead: • Name: Name of a drawbead can be specified. • Input ...: Position of drawbead line can be specified (Curve editor). • Import ...: Drawbead line is imported from CAD. • Copy from ...: Drawbead line is copied from an existing line. Base line and drawbead line are treated as different lines. • Dependent ...: Drawbead line is created from an existing line. Drawbead line is a reference to the base line. This means only the base line can be changed and the dependent drawbead line will also change correspondingly. • Position: Displacement of drawbead line in x–y plane • Width: Width of a drawbead • Forcefactor: Force factor of a drawbead Usage tip – Curve editor A curve – closed or open – may be created using the Curve editor by adding control points (or nodes). Each new control point creates a new curve segment running from the last point to the new one. Curve segments may be linear or curved. It is possible to toggle between two types of segments using the Ctrl key. Holding the Ctrl key down while creating a point with the right mouse button creates a linear segment. 72
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Lesson 5: Full tool (2-step) Simulation
Using just the right mouse button would create a curved segment. It is possible to switch the mode of an existing segment between curved and linear modes by holding the Ctrl key down while clicking (anywhere) on the segment with the right mouse button. Starting the Simulation Job > Start simulation ... > Start job: Start After simulation is completed, the results may be viewed and evaluated in the AutoForm–User Interface by re–opening the simulation file: User interface
File > Reopen The simulation results are shown by the result variable Formability in Fig. 5.6.
Fig. 5.6
Simulation results
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Lesson 5: Full tool (2-step) Simulation The initial blank will be optimized now, i.e. as a result a rectangular or trapezoidal blank will be determined. Click the button Developed blank. Process > Process stage: Developed blank
User interface
The initial blank as calculated on the basis of the OS boundary is shown. Generate a trapezoidal blank on the initial blank using material marks. These material marks are completely connected to the blank and will be defined as a material line. Results > Material marks ... > AutoForm - Material marks: Set marks Fig. 5.7
Position of the material marks Having defined four points on the blank, define these points as material line.
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Lesson 5: Full tool (2-step) Simulation
Fig. 5.8
Coordinates of the material marks AutoForm - Material marks > Define > Material line Activate the process stage containing the actual results of the OneStep simulation. Process > Process stage: Formed sheet
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Lesson 5: Full tool (2-step) Simulation Fig. 5.9
Material line at process stage Formed sheet The material line defined above is now shown on the decklid geometry. Use this line as OS boundary for another Full tool (2-step) simulation. For this export the material line in the process stage Formed sheet: Results > Material lines ... > AutoForm - Material lines: Material line 1 > File > Write selected to file ... > AF Poly3D > Should the data written as CLOSED polylines: Yes > Select a file: Selection: osboundarynew.af > OK Save the simulation under another name. A new simulation file is set up, containing the input data of the existing simulation file. File > Save as ... > Save as: Selection: os_lesson_05b.sim > OK Open the Input generator and go to the Geometry page: Model > Input generator ... > Geometry
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User interface
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Lesson 5: Full tool (2-step) Simulation
Import the new OS boundary now: OS boundary: Import ... > AutoForm - Question: Delete the current os boundary? Delete > AutoForm - Question: Delete currently defined symmetry plane(s)? Delete > Import line(s): Format: af > OK Select a file: osboundarynew.af > OK > Select curve: Pick or select from list: Curve 1 > OK Attention: Attention The existing symmetry–plane has been deleted by the import of the new OS boundary. Go to the Blank page of the Input generator and redefine the symmetry–plane. Start the new simulation and check both the forming results and the shape of the initial blank. Fig. 5.10
Optimized trapezoid blank
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Lesson 6: Optimization
4. 6 Lesson 6: Optimization This lesson describes in a simple example how process parameters can be automatically optimized using the optimization algorithm of AutoForm. Process parameters in OneStep can be the restraining forces at the part boundary. Fig. 6.1
Geometry of optimization example AutoForm offers an optimization algorithm that is fully integrated into the user interface. It allows the user to optimize various input parameters, so that a robust and high–quality part can be produced consistently. Optimization criteria can be defined by the user by using the different FLD zones. In most cases, the criteria will be used to produce a part without any cracks/splits and wrinkles, and having a uniform thickness strain (e.g. 2%) in all areas. Input parameters, which are available for an optimization can be binder forces, drawbead force factors, blank size or tool geometry (using AutoForm–DieDesigner). For all these optimization parameters, the user defines (a) the parameters and (b) the allowable minimum and maximum values of these parameters. Selected optimization parameters are marked in the Input and Geometry generator in yellow (highlighted). Parameter studies are also possible with AutoForm–Optimizer. Input parameters can be automatically varied and the result variations can be analyzed to determine the process sensitivity and dependence on the parameters. The goal is to find the dependency of the results of the drawing process on the parameters and to determine a process window. In the following example an optimization of restraining forces at the part boundary is defined which is based on a completed OneStep simulation.
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Lesson 6: Optimization
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Open the simulation file os_lesson_06_basis.sim: File > Open > os_lesson_06_basis.sim > OK Create an optimization: Model > Input generator … > Create > Optimization First the design variables have to be defined, which will automatically be varied by the optimization algorithm, to achieve better part quality. The restraining forces on the part boundary (Restraining Constant) will be optimized. Proceed as follows: Process
Restraining > Constant Click with the right mouse button the yellow framed input field of the restraining force. A menu titled Add/edit design variable will open (Fig. 6.2).
Fig. 6.2
Menu to define design variable • Name: Name of the design variable • Dependent: Name of a previously defined design variable: This defines a dependent design variable, which means the value of this parameter depends on the previous one. • Independent: Definition of a fully independent design variable • Start: Starting value of design variable to use • Min: Minimum allowable value of design variable • Max: Maximum allowable value of design variable The optimization range of restraining force is between a free part boundary (Forcefactor = 0.0) and a fixed or fully locked part bound-
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Lesson 6: Optimization ary (Forcefactor = 2.0). The start value for the restraining force is a free part boundary (Forcefactor = 0.0). Complete the input for force factor of the first restraining force (design variable) by using the sub–menu titled Design variable definition of the menu Add/edit design variable as follows: Name: rest > Dependent: Independent > Start: 0 > Min: 0 > Max: 2 (Fig. 6.2) > OK Now the background color of input field has changed to yellow. This means the parameter is to be used as a design variable. The name of this variable is displayed in the input field (Fig. 6.3). Fig. 6.3
Menu to define restraining forces Restraining > Constant > The design variable rest (force factor) is defined All design variables have been defined now. Complete the input on Optimize page of Input generator. Switch to this page (Fig. 6.4).
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Process
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Lesson 6: Optimization
Fig. 6.4
Optimize – Design v. page of Input generator Design variables
• Optimization/Parameter study: Definition of optimization or parameter study • Optimization: Optimization will be performed. • Normal random: Parameter study; variables will have a Gaussian distribution around a defined center in parameter range. • Uniform random: Parameter study; variables will have an arbitrary distribution in parameter range. • Regular grid: Parameter study; variables will have a regular distribution in parameter range with a specified number of calculations. • Name: Name of design variable • Current: Current value of design variable for the opened simulation file • Start: Start value of design variable • Min: Minimum value of design variable • Max: Maximum value of design variable Switch to subpage Optimize – Control (Fig. 6.5)
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Lesson 6: Optimization Fig. 6.5
Optimize – Control page of the Input generator • Maximum number of simulations: Maximum number of simulations for an optimization or parameter study. The study will be stopped if the maximum number of iterations is reached • Accuracy: If variation of target function is smaller than the Accuracy value. Optimization/parameter study will be stopped (convergence has been reached).
Iteration control
• All: All simulations are stored on disk (Warning: This requires a large amount of disk space). • Series of best: The next best simulation is always stored on disk. • Only best: Only the best simulation is stored on disk. • None: No simulation is stored on disk.
Keep simulations
User can specify a list of computers which can be used for optimization/parameter study: • Name: Name of computer
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Hosts
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Lesson 6: Optimization • Directory: Directory in which simulations can be stored temporarily • #Lic: Number of AutoForm licenses on computer • #Jobs: Number of jobs, which can run in parallel • Use: Use or do not use this computer for this optimization/ parameter study. • Add host …: Specify a new computer for optimization/ parameter study. • Edit host …: Edit computer parameters for optimization/ parameter study. • Save hosts: Save specified parameters of computers.
No inputs are necessary on Control page for this example. By default, the local computer is selected and activated for usage for optimization/parameter study. The directory in which simulations are stored is the directory from which the AutoForm–User Interface was launched or from which the simulation file was opened. Click on the host name on Control page. Now open the menu named Add/edit hosts by clicking the button Edit host ... (Fig. 6.6) Fig. 6.6
Add/edit host menu on Control page of optimizer Host definition
• Hostname: Name of computers • Get possible executables from host: Search for available AutoForm solvers. Solvers are displayed in the Incremental and Onestep fields. • Working directory: Directory in which the simulation file is stored • Remote shell: Type of shell
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Lesson 6: Optimization • • • • • • • •
Remote copy: Remote copy command Names of executables: Names of AutoForm solvers Incremental: AutoForm–Incremental solver # Incremental licenses: Number of AutoForm–Incremental solver licenses Onestep: AutoForm–Onestep solver # Onestep licenses: Number of AutoForm–Onestep solver licenses OK: OK Cancel: Cancel
Close this menu using Cancel. Switch to the Target page (Fig. 6.7). The target function is defined as follows: • For the whole part including the fill areas, the major strain must be 20% below the Forming Limit Curve (FLC). • Thinning is limited to 30% and thickening is limited to 2%. All other target values Wrinkles and Desired strain should be deactivated (Fig. 6.7).
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Optimize
Lesson 6: Optimization
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Fig. 6.7
Target page of Optimizer • Cracks – Limit % FLC: Target area – Percentage above (+) or below (-) the FLD • Excessive thinning – Acceptable thinning: Maximum acceptable thinning • Wrinkles – Acceptable thickening: Maximum acceptable thickening for wrinkles • Insuff. Stretching – Required thinning: Required thinning • Desired strain – Desired major=minor strain: Desired plastic strain Save the optimization input in file os_lesson_06.opt using the following options: File > Save as … > os_lesson_06.opt > OK Start the optimization using: Run > Start Optimization … > Program: afopt_3.1 > Start (Fig. 6.8)
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Lesson 6: Optimization Fig. 6.8
Optimization manager page
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• Save as plain simulation …: Save as simulation without optimization. • Fork to new optimization ...: Save as a base simulation file for new optimization. • Delete simulations …: Delete the stored simulation files (user–selected). • Strip optimization: Delete all simulation files except base simulation file.
File
• Program: Choice of optimizer version • Start: Start optimization • Open sim.: Opens a stored simulation file from an optimization run. • Base: Choice of stored simulation files from an optimization run • Convergence …: Display of convergence of the optimization run. • Delete sim …: Delete stored simulation files (user– selected). • Dismiss: Close the Optimization manager menu.
Buttons
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Lesson 6: Optimization
Analyze optimization results When all simulations of the optimization run have been successfully completed, open the simulation file using: File > Open optimization > os_lesson_06.opt > OK First open the menu titled Start/manage optimization ... using: Run > Start/manage optimization ... (Fig. 6.9) Fig. 6.9
Optimization manager page is opened when optimization run is completed Use the Convergence ... menu to get a first overview about the number of simulations, behavior of convergence, and the best simulation result. Open the Convergence ... menu using: Run > Start/manage optimization ... > Convergence ... The target function value is displayed over the number of simulations (Fig. 6.10).
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Lesson 6: Optimization Fig. 6.10
Menu Convergence with activated option Target Stored simulations are marked with a bullet, and the best simulation (55th) with a rectangle. Switch to option All criteria (Fig. 6.11). The target function is now divided into single criteria, displayed over the number of simulations in the optimization run. The different criteria of the target function are: • Wrinkles/Insufficient stretching • Desired strain • Cracks/Excessive thinning It can be seen that cracks are the reason for peaks in the target function (Fig. 6.11).
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Lesson 6: Optimization
Fig. 6.11
Menu Convergence with activated option All criteria Switch to the option Log(Target) (Fig. 6.12). The target function value is now displayed in logarithmic form over the number of simulations in the optimization run. The logarithmic representation makes sense because the representation is more concise Fig. 6.12
Menu Convergence with activated option Log(target) Open the first simulation of optimization using: Run > Start/manage optimization ... > Open sim.: 1 > Yes (Fig. 6.13)
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Lesson 6: Optimization Fig. 6.13
Optimization manager page with simulation 1 open Use Ctrl – E to go to the simulation end and switch on the Formability result variable. It can be seen that insufficient stretching occurs in large areas of the part. Fig. 6.14
Simulation 1 of optimization run with result variable Formability Get the current value of the restraining force (Fig. 6.15). Model > Input generator > Optimize > Design v.
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Lesson 6: Optimization
Fig. 6.15
Input generator – Optimize – Design v. page with current value of design variable rest from simulation 1 Now open the best (# 55) simulation of optimization run using: Run > Start/manage optimization ... > Open sim.: 55 > Yes (Fig. 6.16)
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Lesson 6: Optimization Fig. 6.16
Optimization manager page with simulation number 55 open Use Ctrl – E to go to simulation end and switch on result variable Formability. It can be seen that the part is much more uniformly stretched. Fig. 6.17
Simulation 55 of optimization run with result variable Formability Get the current value of restraining force (Fig. 6.18). Model > Input generator > Optimize > Design v.
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Lesson 6: Optimization
Fig. 6.18
Input generator – Optimize – Design v. page with current value of design variable rest of simulation 55
Quit User Interface Quit the user interface using File > Quit or use hotkey Ctrl – Q.
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Lesson 6: Optimization
ALGHAFORM TASARIM BUROSU www.alghaform.com
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