Design and Analysis of 50 Tonne Crane Hook for optimization

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 08, 2015 | ISSN (online): 2321-0613

Design and Analysis of 50 Tonne Crane Hook for Optimization Mr. Nikhil R. Patel1 Mr. Nilamkumar S. Patel2 1 P.G. Student 2Assistant Professor 1,2 Department of Mechanical Engineering 1,2 Ipcowala Institute of Engineering & Technology, Dharmaj, India Abstract—Hooks are employed in heavy industries to carry tonnes of loads safely. These hooks have a big role to play as far as the safety of the hoist loaded is concerned. With more and more industrialization the rate at which these hooks are forged are increasing. This work has been carried out on one of the major hoist hook carrying a larger load comparatively. So in present work the solid modeling and finite element analysis of crane hook has been done using Solidworks and ANSYS workbench. For analysis purpose virtual model of crane hook is prepared by picking data from design data book. Curved beam flexure formula is used for determination of stresses in crane hook analytically. Finite Element Analysis have been performed on trapezoidal cross sections. To investigate the static stress results, both finite element method and exact solution method are applied and compare the stress results obtained by finite element and exact solution methods. From the output of these analyses it is observed that results obtained are in close agreement with each other and maximum stress concentration occurs at inner most surfaces. Key words: Crane Hook, Curved Beam Flexure Formula, Finite Element Analysis, Solidworks, ANSYS Workbench I. INTRODUCTION Crane and hoisting machine are used for lifting heavy loads and transferring them from one place to another. Crane Hooks are highly liable components that are typically used for industrial purposes. Crane hooks with trapezoidal, circular, rectangular and triangular cross section are commonly used. Thus, such an important component in an industry must be manufactured and designed in a way so as to deliver maximum performance without failure. Products are designated just like clevis hooks, grab hooks, or eye hooks, and are used to connect lifting and rigging attachments. Most industrial products like hooks, which are forged from alloy steel, stainless steel, or carbon steel, and then quenched and heat treated. In this project work stress analyses of crane hook with trapezoidal cross section and load carrying capacity is 50 tonne as per IS: 3815-1969 have been carried out.[1] The crane hook is manufactured by EN3A steel material having Indian standard 4367-1967. [2] Firstly, the 3-D model of the hook is built used Solidworks. Secondly, the static analysis on the hook is proceeded by FEM software ANSYS. From the view point of safety, the stress induced in crane hook must be analyzed in order to reduce failure of hook. II. FAILURE OF CRANE HOOKS To minimize the failure of crane hook [3], the stress induced in it must be studied. Crane is subjected to continuous loading and unloading. This causes fatigue of the crane hook but the fatigue cycle is very low. If a crack is developed in the crane hook, it can cause fracture of the hook and lead to serious Accident. In ductile fracture, the crack propagates

continuously and is more easily detectible and hence preferred over brittle fracture. In brittle fracture, there is sudden propagation of the crack and hook fails suddenly [4]. This type of fracture is very dangerous as it is difficult to detect. Strain aging embrittlement [5] due to continuous loading and unloading changes the microstructure. Bending stresses combined with tensile stresses, weakening of hook due to wear, plastic deformation due to overloading, and excessive thermal stresses are some of the other reasons for failure. Hence continuous use of crane hooks may increase the magnitude of these stresses and ultimately result in failure of the hook. III. METHODOLOGY A virtual model of IS: 3815 lifting hook similar to actual sample is created using SOLIDWORKS software and then model was imported to ANSYS workbench for Finite element stress analysis and the result of stress analysis are cross checked with that of Curved beam flexure formula for curved beams. IV. STRESS CALCULATION OF CRANE HOOK The crane hook is a curved beam [6], simple theory of bending for shallow, straight beam does not yield accurate results. Stress distribution across the depth of such beam, subjected to pure bending, is nonlinear (to be precise, hyperbolic) and the position of the neutral surface is displaced from the centroidal surface towards the Centre of curvature. In case of hooks as shown in Figure 1, the members are not slender but rather have a sharp curve and their cross-sectional dimensions are large compared to their radius of curvature.[7]

Fig. 1: Curved beam with its cross section area The curved beam flexure formula is in reasonable agreement for beams with a ratio of curvature to beam depth (𝑟𝑐 /h) > 5 (rectangular section). As this ratio increases, the difference between the maximum stress calculated by curved beam formula and the normal beam formula reduces. The above equations are valid for pure bending. In case of crane hooks, the bending moment is due to forces acting on one side of the section under consideration. For calculations the area of cross section is assumed to be trapezoidal [8].

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Design and Analysis of 50 Tonne Crane Hook for Optimization (IJSRD/Vol. 3/Issue 08/2015/149)

A. Calculation for 50 Tonne Crane Hook

Fig. 2: Trapezoidal cross section of hook Load carrying capacity, F = 50 tonne = 490500 N Inner dia. of hook, C = 240mm bi = 150 mm bo = 60 mm Inner radius of curve beam, ri = C/2 =120 mm. Outer radius of curve beam, ro = ri +C = 120+240 = 360 mm. Depth of the section, h = 240mm. Radius of the neutral axis, rn = 1 h (bi + bo ) 2 bi ro −bo ri h 1

ln

ri

− (bi − bo )

240 (150 + 60)

2 (150×360)−(60×120) 240

ro

ln

360 120

− (150 − 60)

= 202.851 mm. Distance of centroidal axis from inner fiber, C1 = h bi + 2bo [ ] 3 bi + bo 240 150 + 120 = [ ] 3 150 + 60 =102.857 mm. Radius of centroidal axis, rc = ri + C1 = 120+102.857 = 222.857 mm Distance of neutral axis to centroidal axis, e = rc − rn = 222.857 – 202.851 = 20.006 mm. Distance of neutral axis to inner radius, Ci = rn − ri = 202.851 – 120 = 82.851 mm. Distance of neutral axis to outer radius, Co = ro − rn = 360 – 202.851 = 157.149 mm. Distance from centroidal axis to force, l = rc =222.857 mm. 1 Area of cross section, A = h(bi + bo ) 2 1 = 240(150 + 60) 2 2 = 25200 mm Bending moment about centroidal axis, Mb = F. l = 490500×222.857 = 1.093×108 N.mm Direct stress,

F A =19.464 N/mm2 Bending stress at the inner fiber, M b Ci σbi = Aeri = 144.533 N/mm2 (Tensile) Bending stress at the outer fiber, M b Co σ bo = − Aero = - 93.426 N/mm2 (Compressive) Combined stress at inner fiber, σri = σd + σbi = 19.464 + 144.533 = 163.997 N/mm2 (Tensile) Combined stress at outer fiber, σro = σd + σbo = 19.464 - 93.426 = - 73.962 N/mm2 (Compressive) Maximum shear stress, τmax = 0.5×σmax = 0.5×163.997 = 81.5425 N/mm2 at inner fiber. In exact solution method, a simple hook is considered as curved beam and the maximum stress on inner concave and the minimum stress on outer convex surfaces are calculated as σmax = 163.997 N/mm2 and σmin = -73.962 N/mm2 respectively.[9] σd =

V. DIMENSIONS, DESIGNATION AND MATERIAL OF HOOK The hook having Trapezoidal cross section as per IS: 38151969 has been considered for modeling in SOLIDWORKS software. Dimensions chosen for hook are tabulated below: Dim. Dim. Parameters Parameters (mm) (mm) D 240 R 30 S 180 170 Ra b 150 130 Rb h 240 320 Rc d 160 65 Rd 140 240 d1 Re l 330 280 Rf Rg 150 40 l1 120 5 l2 Rℎ L 730 Table 1: Dimensions of crane hook

Fig. 3: Geometry of the single hook

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Design and Analysis of 50 Tonne Crane Hook for Optimization (IJSRD/Vol. 3/Issue 08/2015/149)

Type of material used for crane hook is EN3A steel material having Indian standard 4367-1967. The material properties are: 1) Ultimate tensile strength 50-60 kg⁄mm2 2) Yield stress(Min) 29 kg⁄mm2 3) Elongation ( Min ) 20% 4) Hardness 140-180 BHN VI. PREPARATION OF CAD MODEL OF HOOK

For the selection of static analysis fixed support is chosen at shank end and the force is applied in y direction for selected materials of structural steel, now the solution is let to solve and Von-mises stresses are detected for trapezoidal hook. For analyzing the cross-section of the crane hook after and when it is designed in the SOLIDWORKS, loads are applied to check that how much load the designed crane hook with stands. The process of applying load and the results obtained in the Ansys are indicated below.

For generation of CAD model of crane hook various geometrical features and dimensions are selected from IS: 3815-1969. Some features are approximated for simplification. SOLIDWORKS-2014 software is used for creating solid model of hook. Complete Solid CAD model is prepared which is shown in fig.4 and it is saved in .igs format.

Fig. 7: Boundary Conditions and Application of Load Fig. 4: SolidWorks model of crane hook. VII. STRESS ANALYSIS USING FEM The solid CAD model in .IGS format is imported to ANSYS for FEA. Meshing is important part of Finite Element Method. The mesh taken has Tetrahedron shape. Simulation process meshing of the model is generated as shown in Fig.5 the mesh details done in the CAD model is shown in Table2. The nodes and elements created by meshing are given below: [10] Fig. 8: Fixed Support

Fig. 5: ANSYS .IGS file from SOLIDWORKS Nodes 14127 Elements 8114 Table 2: Mesh details

Fig. 6: Meshed model of crane hook.

Fig. 9: Equivalent (Von-Mises) Stress Distribution

Fig. 10: Total Deformation

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Design and Analysis of 50 Tonne Crane Hook for Optimization (IJSRD/Vol. 3/Issue 08/2015/149)

REFERENCES

Fig. 11: Maximum Shear Stress VIII. COMPARISON OF STRESSES For the model of crane hook, the induced stresses as obtained from analytical calculations are compared with results obtained by FEA software. [11] A. ANSYS v/s Analytical Innermost point of section: Max stress by ANSYS= 149.09 N/mm2; Max stress analytically= 163.997 N/mm2 % error = (163.997 – 149.09)/149.09 = 9.99 % Outermost point of section: Stress by ANSYS= 67.595 N/mm2; Stress analytical= 73.962 N/mm2; % error = (73.962-67.595)/67.595 = 9.41 % Stresses obtained for the hook by ANSYS and Curved beam flexure formula is tabulated below: Outer stress Inner Stress (MPa) (MPa) 163.997 73.962 Analytical 149.09 67.595 ANSYS 9.99 9.41 % Error Table 3: ANSYS and Curved beam flexure formula

[1] IS-3815-1969 Specification for forged crane hook. [2] IS-4367-1967, ‘Specification for alloy and tool steel Forging for general industrial use’. [3] B. Ross, B. McDonald and S. E. V. Saraf, “Big Blue Goes Down. The Miller Park Crane Accident,” Engineering Failure Analysis, Vol. 14, No. 6, 2007 pp. 942-961. [4] J. Petit, D. L. Davidson and S. Suresh, “Fatigue crack Growth under Variable Amplitude Loading,” Springer Publisher, New York, 2007. [5] Y.yokoyamal, "Study of Structural RelaxationInduced Embrittlement of Hypoeutectic Zr-Cu- Al", Ternary Bulk Glassy Alloys, Acta Material, Vol. 56, No. 20, pp. 6097-6108, 2008. [6] Curved Beam Analysis. www.roymech.co.uk/Useful_Tables/Beams/Curved_be ams.html [7] Rashmi Uddanwadiker, “Stress Analysis of Crane Hook and Validation by Photo-Elasticity”, Engineering, 2011, 3, 935-941. [8] H. A. Rothbart, “Mechanical Design Handbook: Measurement, Analysis, and Control of Dynamic Systems,” McGraw-Hill, Columbus, 2006. [9] L.S. Srinath, “Advanced Mechanics of solids”, 3rd edition, pp.: 209-216. [10] G. U. Rajurkar, Dr. D. V. Bhope et. al, “Investigation Of Stresses In Crane Hook By FEM,” International Journal of Engineering Research & Technology, ISSN: 2278-0181, Vol. 2 Issue 8, August – 2013, pp. 117122. [11] Yogesh Tripathi,” Comparison of stress between winkler-bach theory and ANSYS Finite Element Method for crane hook with a Trapezoidal crosssection”.Volume:02 Issue: 09 sep-2013.

IX. DESIGN IMPROVEMENT From the stress analysis we have observed the cross section of max stress area. If the area on the inner side of the hook at the portion of max stress is widened then the stresses will get reduced. Thus the design can be modified by increasing the thickness on the inner curvature so that the chances of failure are reduced considerably. This model has an important meaning to design larger tonnage lifting hook correctly. X. CONCLUSION The complete study is an initiative to establish a FEA procedure, by validating the results, for the measurement of stresses. For reducing the failures of hooks the estimation of stresses, their magnitudes and possible locations are very important. The main aim of this paper is to improve quality of crane hook to withstand bending stress and structural stresses and at the same time reduce stress concentration of the crane hook. So the further scope of work is optimization of design of crane hook by changing parameters like inner and outer thickness of crane hook cross section.

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