Structural Analysis of Bolero Maxi-Truck Chassis using ANSYS 14.5

Transcription

1 IJIRST International Journal for Innovative Research in Science & Technology Volume 2 Issue 11 April 2016 ISSN (online): Structural Analysis of Bolero Maxi-Truck Chassis using ANSYS 14.5 Mr. Takale Mayuresh U UG Student Department of Automobile Engineering Mumbai university, Maharashtra, India Mr. Mohotkar Prithviraj S UG Student Department of Automobile Engineering Mumbai university, Maharashtra, India Mr. Shet Shirodkar Sanket K UG Student Department of Automobile Engineering Mumbai university, Maharashtra, India Mr. Mahadik Omkar P UG Student Department of Automobile Engineering Mumbai university, Maharashtra, India Mr. Rawool S. D Assistant Professor Department of Automobile Engineering RMCET Ambov, Maharastra, India. Abstract Chassis is a main component of the vehicle. This work involves static and dynamics analysis to determine the key characteristics of a Bolero Maxi-Truck chassis. The modelling of the chassis was done by using the modelling software AUTODESK INVENTOR PROFESSIONAL 2016 and then imported into finite element package ANSYS The analysis was done by using one of the most important numerical methods is FEA and the software used is ANSYS 14.5.The static characteristics include identifying location of high stress area and maximum deformation area of the chassis. The dynamic characteristics of maxi-truck chassis such as the natural frequency and mode shape were determined by using finite element (FE) method. In the analysis, the behaviour of the chassis will be shown in 6 mode shapes. Modal updating of the truck chassis model was done by adjusting the selective properties such as mass density and Poisson s ratio. Modifications have been suggested on the current chassis. Finally, the modification of the bolero maxi-truck chassis model was proposed to reduce the stress, deformation & weight of the truck chassis. The static structural analysis was done at different mesh conditions and results will be tabulated and graphs were plot. The results obtained from the modified chassis are compared with the original chassis, and the most optimized chassis is presented. Keywords: ANSYS14.5, Autodesk Inventor professional, Ladder frame chassis, Modal analysis, Structural analysis, Weight reduction I. INTRODUCTION A chassis is a very important component of the vehicle. It should be rigid enough to withstand shocks, vibrations, stresses etc. Therefore maximum stress and deformation are important criteria for chassis design. Usually, customers tend to carry extra amount of load on the vehicle than the load limit specified by the manufacturer. This produces large amount of stresses which can lead to fatigue failure of the chassis. So, in order to eliminate such failures we need to modify the design of the chassis by changing the geometrical properties which will reduce the stresses induced. Static structural analysis is used to determine maximum stress, maximum defection & its position. When you perform a prestressed modal analysis, the support conditions from the static analysis are used in the modal analysis. You cannot apply any new supports in the modal analysis portion of a pre-stressed modal analysis. Modal analysis is technique used to determine vibration characteristic (natural frequency & modal analysis) of structure. Problem statement The main focus of paper is to reduce stress of the chassis, reduce the weight and increases its performance standard. The reduced stress can be achieved by changing the geometrical shape structure where maximum stress is applied. Experimental objective To determine the stresses generated in the chassis. To improve the static behavior of the chassis by changing the geometrical dimension and structural properties to reduce the stresses. To compare the effect of various behavior of cross-sections taken into consideration. The various sub objective is listed below: Static structural analysis: All rights reserved by 504

2 To find the Von-Mises stresses and its position. To find minimum and maximum deflection and its position. Modal analysis: To find the mode shape and natural frequency of the chassis. II. METHODOLOGY The finite element method is a numerical technique for finding approximate answer to boundary value problem. It is a powerful analysis tool used for subdivide large problem into smaller, parts called as finite element. Formation 3D CAD model: The 3D modelling of the chassis is done using Autodesk inventor professional 2016 software and saved in a neutral format such as.igs format. Importing: Import the CAD geometry into the FEA package ANSYS Material properties: The material of chassis is tested in Metasys testing and calibration laboratories, Kolhapur and according to their results the material properties are defined in the FEA package. The material to be used is mild steel. Meshing: In this operation the CAD model is divided into large number of small pieces called mesh. By using various meshing feature of ANSYS 14.5 the results are calculated and by using convergence theory a specific mesh condition is considered for further analysis. Boundary conditions: Fixed supports are provided beneath the chassis to act as the support from axles/suspension. Effects of rivets and welded joints are ignored and the chassis is considered to be uniformly joined. Solve: The FEA package ANSYS 14.5 solves the model with the given mesh and loads for static, modal analysis. Post processing: The reviewing of the results and the solutions are carried out in ANSYS 14.5 itself. The results are in the various formats such as: graph, values and animations. Material properties The material that has been used in the manufacture of the chassis frame is Structural Steel. The physical and mechanical properties of the steel are listed below: 1) Density = 7850 kg/m3 2) Young s modulus = 2E+11 Pa 3) Poisson s ration = ) Bulk Modulus = 1.692E+11 Pa 5) Shear Modulus = E+11 Pa 6) Ultimate tensile strength = MPa 7) Yield tensile strength = MPa 8) Yield compressive strength = 250 MPa III. GEOMETRIC MODELING OF CHASSIS The modeling of the chassis was done by using the modelling software AUTODESK INVENTOR PROFESSIONAL It has two side member and 10 cross members as shown in figure (1) below. Fig. 1: Model of chassis Analysis of Existing Chassis: Static Structural Analysis: Static Structural Analysis was being carried out in order to find the stresses and deformations. Under this analysis different mesh conditions were used to obtain accurate results. Different meshing conditions: Mesh Sizing: Element sizing = 200mm; Element sizing = 100mm; Element sizing = 25mm; Element sizing = 15mm; All rights reserved by 505

3 Element sizing = 50mm; Element sizing = 10mm; Mesh Methods: 1) Tetrahedron (Patch Conforming Method) 2) Tetrahedron (Patch Independent Method) 3) Hex Dominant Effect on stresses and deformations due to various mesh conditions: Mesh sizing Case 1: Element size = 200 mm Fig. 2: Total deformation Fig. 3: Equivalent (von-mises) stress Case 2: Element size = 100 mm Fig. 20: Engine mounting bracket (location of max stress) All rights reserved by 506

4 Fig. 4: Total deformation Fig. 5: Equivalent (Von-Mises) stress Case 3: Element size = 50 mm Fig. 6: Total deformation Fig. 7: Equivalent (Von-Mises) stress Case 4: Element size = 25 All rights reserved by 507

5 Fig. 8: Total deformation Fig. 9: Equivalent (Von-Mises) stress Case 5: Element size = 15 mm Fig. 10: Total deformation Fig. 11: Equivalent (Von-Mises) stress All rights reserved by 508

6 Case 6: Element size = 10 mm. Fig 12: Total deformation Fig 13: Equivalent (Von-Mises) stress Case 7: Using tetrahedron (PCM) mesh method Fig. 14: Total deformation Fig. 15: Equivalent (Von-Mises) stress Case 8: Using tetrahedron (PIM) mesh method All rights reserved by 509

7 Fig 16: Total deformation Case 9: Using Hex Dominant mesh method Fig 17: Equivalent (Von-Mises) stress Fig 18: Total deformation Fig 19: Equivalent (Von-Mises) stress Observation table and graph Table No - 1: Observation table for static structural analysis Sr. No. Element Type Total Deformation (mm) Equivalent Stress (MPa) Min Max Min Max mm mm mm mm mm All rights reserved by 510

8 6 10 mm Tetrahedron (PCM) Tetrahedron (PIM) hex dominant Fig. 21: Bar graph (Stress Vs Element type) Conclusion for Static Structural Analysis: From the above analysis, it can be seen that the stresses are not constant for different face sizing elements and mesh methods. But for 10mm face sizing and tetrahedron mesh method (i.e. PCM) we get constant stresses and deformation. Also smaller the element size, the results will be more accurate. By using convergence theory, for further analysis we have considered face sizing as 10mm. IV. MODIFICATION OF THE DESIGN From the current design details, it is found that maximum stresses are generated at the engine brackets and max deformation is obtained at the engine brackets, gear box mounting section and fuel tank mounting section. So, in order to minimize these stresses and deformation, modification in the design of chassis were made. Modifications done: 1) Fillet given at the inner corners of engine bracket. 2) Increased the thickness of cross member where the gear box is mounted. 3) Changed the cross section of the cross member where fuel tank is mounted. 4) C section, I section, Rectangular section Static structural analysis Case 1: C section Fig. 22: Modify engine bracket Fig. 23: Meshing & C section All rights reserved by 511

9 Fig. 24: Total deformation Fig. 25: Equivalent (Von-Mises) stress Case 2: I-section Fig. 26: Meshing & I section (enlarged view) Fig. 27: Total deformation All rights reserved by 512

10 Fig. 28: Equivalent (Von-Mises) stress Case 3: Rectangular section Fig. 29: Meshing & Rectangular section (enlarged view) Fig. 30: Total deformation Fig. 31: Equivalent (Von-Mises) stress All rights reserved by 513

11 Observation Table and Graph: Table No - 2: Observation table for static structural analysis of various cross-sections. Sr. No. Cross Section Total Deformation(mm) Equivalent Stress (MPa) Min Max Min Max 1 Hat section (original chassis ) 'C' Section E 'I' Section E Rectangular section E Hat section (original chassis ) Cross section v/s stresses and deformation Rectangular section 'I' Section 'C' Section Equivalent Stress (Mpa) Max Total Deformation(mm) Max Fig. 32: Bar graph (cross-section Vs stress & deformation) Effect on weight of the chassis due to changes in design On changing few geometrical factors, there was some effect on the weight of the chassis The original chassis was weighing about kg. The current weight of the chassis (i.e. after changing its design) is shown in table below: Table - 3 Effect on weight of the chassis due to changes in design Sr. No. Cross Section Total Weight (Kg) 1 Hat section (original chassis weight ) Rectangular section 'C' Section 'I' Section Discussion The modification of chassis in contrast with the existing chassis has been carried out by iterating on various design factor. From above data i.e. table no 1, fig 9.4 and table no 3, discussion were carried out and chassis with cross member having I-section is considered as an optimum design. Further, modal analysis on this modified design is carried out. V. MODAL ANALYSIS OF THE CHASSIS In order to find natural frequency and mode shape of structural component modal analysis is carried out. Natural frequency: At what frequencies the structure would tend to naturally vibrate. Mode shape: In what shape the structure would tend to vibrate at each frequency. Modal analysis is done in free-free boundary condition. Natural frequency of the structural component should not match with the excitation frequency in order to avoid the resonance phenomenon. Boundary Conditions of Modal Analysis In the modal analysis, chassis has fixed support at rear axle and front axle. It means that all degree of freedom at rear axle and front axle are fixed. No external force is applied to the chassis. In this analysis we have extracted 6 different modes of vibration. All rights reserved by 514

12 Various Mode Shape & Their Frequencies: Fig. 33: Mode Shape 1 Fig. 34: Mode Shape 2 Fig. 35: Mode Shape 3 Fig. 36: Mode Shape 4 All rights reserved by 515

13 Fig. 37: Mode Shape 5 Fig. 38: Mode Shape 5 Mode Shape results in tabular form Table - 4 Mode shapes and their frequencies. Sr. No. Mode Shapes Frequency Total Deformation (Hz) (mm) Min Max 1 Mode Shape Mode Shape Mode Shape Mode Shape Mode Shape Mode Shape VI. CONCLUSION The modification was done on the current design to optimize the results. Natural frequency and mode shape are obtained. A total of 4 modifications were carried out, from which 2 designs were selected (i.e. fillet at engine bracket and I-section cross member) which were examined w. r. t. existing chassis. The modified chassis is presented as more ideal chassis with a reduced Von-Mises stress of 34.57MPa (20.32%) and reduced weight of 1kg. ACKNOWLEDGMENT Working on this project was one of the wonderful and existing experiences in our life. This project not only bears testimony of extensive efforts but also reflects co-operations, help and guidance, which we received time to time from college. It is obvious that we acknowledge the help without which the project would never have been completed. We would like to thank UNIVERSITY OF MUMBAI for giving us opportunity to apply our knowledge and skills in practical environments part of curriculum. We owe this moment of satisfaction with dear sense of gratitude to our project guide PROF. RAWOOL S. D. and PROF. WATEGAONKAR R. D. for his valuable guidance, suggestions and active involvement in our project. We are also thankful to the head of department of automobile engineering PROF. DHOLE N. S. and our principal DR. BHAGWAT M. M. without whose help this project would have been impossible. We thank deeply to invaluable guidance rendered to us all occasion by all others to directly or indirectly contribute to our humble performance. Also, we would like to thank SAHYADRI MOTORS PVT. LTD., SATARA and METASYS TESTING AND CALIBRATION LABORATORIES LLP, SHIROLI-KOLHAPUR for providing us the necessary details for this project. All rights reserved by 516

14 REFERENCES [1] Sairam Kotari, V. Gopinath STATIC AND DYNAMIC ANALYSIS ON TATRA CHASSIS, International Journal of Modern Engineering Research (IJMER) Vol.2, Issue.1, pp [2] Dr.R.Rajappan, M.Vivekanandhan, Static and Modal Analysis of Chassis by Using FEA, The International Journal Of Engineering And Science (IJEAS), Volume 2, Issue 2, Pages [3] Patel Vijaykumar V, Prof. R. I. Patel, Structural Analysis of Automotive Chassis Frame and Design Modification for Weight Reduction, International Journal of Engineering Research & Technology (IJERT) Vol. 1 Issue 3, May ISSN: [4] Ketan Gajanan Nalawade, Ashish Sabu, Bhaskar P, Dynamic (Vibrational) and Static Structural Analysis of Ladder Frame, International Journal of Engineering Trends and Technology (IJETT) Volume 11 Number 2 - May [5] Indu Gadagottu, M. V. Mallikarjun, STRUCTURAL ANALYSIS OF HEAVY VEHICLE CHASSIS USING HONEY COMB STRUCTURE, International journal of mechanical engineering and robotics research ISSN Vol. 4, No. 1, January IJMERR. [6] M. Ravi Chandra, S. Sreenivasulu, Syed Altaf Hussain, Modeling and Structural analysis of heavy vehicle chassis made of polymeric composite material by three different cross sections, International Journal of Modern Engineering Research (IJMER) Vol.2, Issue.4, July-Aug pp ISSN: [7] Hirak Panchal, Khushbu C. Patel, Chetan S. Jadav, Structural Analysis of Truck Chassis Frame and Design Optimization for Weight Reduction, International Journal of Engineering and Advanced Technology (IJEAT) ISSN: , Volume-2, Issue-4, April 2013 [8] Ahmad O. Moaaz, Nouby M Ghazaly, A Review of the Fatigue Analysis of Heavy Duty Truck Frames, American Journal of Engineering Research (AJER) e-issn: p-issn : Volume-3, Issue-10, pp [9] K. P. Sirisha, R. Lalith Narayana, A. Gopichand, Ch. Srinivas, G. Ram Balaji Structural and Modal Analysis on A Frame Less Chassis Construction of Heavy Vehicle for Variable Loads International Journal of Engineering Research and Applications (IJERA) ISSN: Vol. 3, Issue 4, Jul-Aug 2013, pp [10] Prof. Byra Reddy & Prof. Dadapeer B Design and Analysis of A Ladder Frame Chassis for Static and Dynamic Characteristics International Journal of Latest Trends in Engineering and Technology (IJLTET) ISSN: X Vol. 6 Issue 1 September [11] Goutham Solasa, Nariganani SD Satadeep, T.Raghu Krishna Prasad, G.Suresh Babu Modal Analysis of Chassis International Journal of Engineering and Advanced Technology (IJEAT) ISSN: , Volume-2, Issue-4, April 2013 All rights reserved by 517