A Thesis entitled Design, Analysis and Optimization of Rear Sub-frame using Finite Element Modeling and Modal Analysis by Gaurav Kesireddy Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Mechanical Engineering _________________________________________ Dr. Hongyan Zhang, Committee Chair _________________________________________ Dr. Sarit Bhaduri, Committee Member _________________________________________ Dr. Matthew Franchetti, Committee Member _________________________________________ Dr. Amanda Bryant-Friedrich, Dean College of Graduate Studies The University of Toledo May 2017 Copyright 2017, Gaurav Kesireddy This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of Design, Analysis and Optimization of Rear Sub-frame using Finite Element Modeling and Modal Analysis by Gaurav Kesireddy Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Mechanical Engineering The University of Toledo May 2017 A sub-frame is a structural component of an automobile that carries suspension, exhaust, engine room, etc. The sub-frame is generally bolted to Body in White(BIW). It is sometimes equipped with springs and bushes to dampen vibration. The principal purposes of using a sub-frame are, to spread high chassis loads over a wide area of relatively thin sheet metal of a monocoque body shell, and to isolate vibration and harshness from the rest of the body. As a natural development from a car with a full chassis, separate front and rear sub-frames are used in modern vehicles to reduce the overall weight and cost. In addition, a sub-frame yields benefits to production in that subassemblies can be made which can be introduced to the main body shell when required on an automated line. The objective of the project is the design, analysis and optimization of Rear Sub-frame considering the modal analysis and natural frequency of the system using Altair Hypermesh®, Optistruct®, RADIOSS® and Altair HyperView®. iii Acknowledgements I would like to thank Dr. Hongyan Zhang and Dr. Wang Bin for their guidance and patience during my time at The University of Toledo. Their support and encouragement has helped me in addition to countless other students at aspiring highest goals in the field of mechanical engineering. Special thanks to Dr. Sarit Bhaduri and Dr. Mathew Franchetti for evaluating my work and being a member of my thesis defense committee. Lastly, I would like to thank my friends and family for their patience, support and all the encouragement they have provided during this stressful period of my life. iv Table of Contents Abstract .............................................................................................................................. iii Acknowledgements ............................................................................................................ iv Table of Contents .................................................................................................................v List of Tables .................................................................................................................. viii List of Figures .................................................................................................................... ix List of Abbreviations ........................................................................................................ xii List of Symbols ................................................................................................................ xiii 1 Introduction ..........................................................................................................1 1.1 Introduction to Design .......................................................................................1 1.2 Noise, Vibration and Harshness .........................................................................2 1.2.1 Normal Mode Analysis .......................................................................3 1.2.2 Degrees of Freedom ............................................................................5 1.2.2.1 Single Degree of Freedom ...................................................5 1.2.2.2 Multiple Degree of Freedom ................................................6 2 Literature Review and Background .........................................................................8 2.1 Literature Review...............................................................................................8 2.2 Manufacturability .............................................................................................10 2.3 Design Considerations .....................................................................................11 v 3 Tools and Resources ..............................................................................................12 3.1 FEM & FEA .........................................................................................12 3.1.1 FEA Process Introduction .................................................................13 3.1.2 Pre-Analysis Processing....................................................................14 3.2 Mesh Generation ..............................................................................................14 3.2.1 Mesh Setup........................................................................................14 3.3 Converting Solid Bodies to Surface Bodies.....................................................17 3.4 Creating New Simulation and Finite Element Model ......................................20 3.4.1 Element Simulated Physical and Material Properties .......................24 3.4.2 1D,2D & 3D Mesh ............................................................................26 3.4.3 Simulation Constraints and Loading Applications ...........................27 3.4.3.1 Constraints .........................................................................27 3.4.3.2 Load & Other Factors ........................................................28 3.5 Solving Simulations .........................................................................................29 3.6 Post-Processing Results ...................................................................................30 4 Simulation Loading Scenarios ...............................................................................33 4.1 Loading Conditions ..........................................................................................33 4.1.1 Two-Wheel Bump .............................................................................34 4.1.2 Forward Braking ...............................................................................34 4.1.3 Reverse Braking ................................................................................35 4.1.4 Cornering ..........................................................................................35 4.1.5 Forward Acceleration........................................................................35 4.1.6 Reverse Acceleration ........................................................................35 vi 4.1.7 Max Torque .......................................................................................35 5 Sub-frame Modified Design ..................................................................................36 5.1 Design Space ....................................................................................................36 5.2 Optimization and Results .................................................................................38 6 Conclusions .......................................................................................................54 6.1 Conclusions ......................................................................................................54 References ..........................................................................................................................56 Appendix A: Types of Load Cases and Results.................................................................58 Appendix B: Original and New sub-frame FEA Results ...................................................60 vii List of Tables 3.1 Physical properties of steel ....................................................................................25 3.2 Frequency and Mode shape of original sub-frame ................................................31 5.1 Frequency and Mode shape of optimized result ....................................................42 5.2 Frequency and Mode shape of Final sub-frame .....................................................44 5.3 Comparison between original and optimized model .............................................45 5.4 Von-Mises Maximum Stress Comparison of Optimized and Original model .......46 5.5 Component Mass and Name ..................................................................................47 5.6 Summary Table of new and original sub-frames ...................................................52 viii List of Figures 1-1 Original Sub-frame CAD model ..............................................................................1 1-2 Modal analysis of a car body ...................................................................................4 1-3 Single DOF System..................................................................................................6 1-4 2-DOF System .........................................................................................................7
Details
-
File Typepdf
-
Upload Time-
-
Content LanguagesEnglish
-
Upload UserAnonymous/Not logged-in
-
File Pages78 Page
-
File Size-