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Simulation of Electrohydraulic Forming Using Anisotropic, Rate-Dependent Plasticity Models Amir Hassannejadasl University of Windsor

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Simulation of Electrohydraulic Forming Using Anisotropic, Rate-Dependent Plasticity Models Amir Hassannejadasl University of Windsor University of Windsor Scholarship at UWindsor Electronic Theses and Dissertations 2014 Simulation of Electrohydraulic Forming Using Anisotropic, Rate-dependent Plasticity Models Amir Hassannejadasl University of Windsor Follow this and additional works at: http://scholar.uwindsor.ca/etd Recommended Citation Hassannejadasl, Amir, "Simulation of Electrohydraulic Forming Using Anisotropic, Rate-dependent Plasticity Models" (2014). Electronic Theses and Dissertations. Paper 5205. This online database contains the full-text of PhD dissertations and Masters’ theses of University of Windsor students from 1954 forward. These documents are made available for personal study and research purposes only, in accordance with the Canadian Copyright Act and the Creative Commons license—CC BY-NC-ND (Attribution, Non-Commercial, No Derivative Works). Under this license, works must always be attributed to the copyright holder (original author), cannot be used for any commercial purposes, and may not be altered. Any other use would require the permission of the copyright holder. Students may inquire about withdrawing their dissertation and/or thesis from this database. For additional inquiries, please contact the repository administrator via email ([email protected]) or by telephone at 519-253-3000ext. 3208. Simulation of Electrohydraulic Forming Using Anisotropic, Rate-dependent Plasticity Models by Amir Hassannejadasl A Dissertation Submitted to the Faculty of Graduate Studies through the Department of Mechanical, Automotive & Materials Engineering in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy at the University of Windsor Windsor, Ontario, Canada 2014 © 2014 Amir Hassannejadasl Simulation of Electrohydraulic Forming Using Anisotropic, Rate-dependent Plasticity Models by Amir Hassannejadasl APPROVED BY: ___________________________________________ Dr. P.D. Wu, External Examiner McMaster University ______________________________________________ Dr. S.F. Golovashchenko, Industrial Advisor Ford Research & Advanced Engineering, Dearborn, MI ______________________________________________ Dr. S. Cheng Department of Civil and Environmental Engineering ______________________________________________ Dr. N. Zamani Department of Mechanical, Automotive & Materials Engineering ______________________________________________ Dr. W. Altenhof Department of Mechanical, Automotive & Materials Engineering ______________________________________________ Dr. D.E. Green, Advisor Department of Mechanical, Automotive & Materials Engineering September 11, 2014 ii Declaration of Previous Publication This dissertation includes one original paper that will be published in the proceedings of the ICTP2014 conference (Nagoya, Japan). Two journal papers were written and are ready to be submitted for publication. However, due to co-authorship limitation and requirements, these papers are on hold at the present time and they will be submitted as soon as the other partner of this project (University of Waterloo) receives their final publication approval. Thesis Chapter Publication title/full citation Publication status Chapter 4 Prediction of DP600 flow surfaces at “accepted for Publication” various strain-rates using Yld2004- 18p yield function I certify that I have obtained a written permission (Appendix-A3) from the copyright owner(s) to include the above published material in my dissertation. I certify that the above material describes work completed during my registration as graduate student at the University of Windsor. I declare that, to the best of my knowledge, my dissertation does not infringe upon anyone’s copyright nor violate any proprietary rights and that any ideas, techniques, quotations, or any other material from the work of other people included in my dissertation, published or otherwise, are fully acknowledged in accordance with the standard referencing practices. Furthermore, to the extent that I have included copyrighted material that surpasses the bounds of fair dealing within the meaning of the Canada Copyright Act, I certify that I have obtained a written permission from the copyright owner(s) to include such material(s) in my dissertation. I declare that this is a true copy of my dissertation, including any final revisions, as approved by my dissertation committee and the Graduate Studies office, and that this dissertation has not been submitted for a higher degree to any other University or Institution. iii Abstract Electrohydraulic forming (EHF) is a pulsed forming process in which two or more electrodes are positioned in a chamber filled with a liquid and a high-voltage discharge between the electrodes generates a high-pressure to form the sheet. Deformation history of a sheet material in EHF process shows substantial changes in the strain rate of the material during the forming process. In this research, the mechanical properties of DP600, TRIP780, and AA5182-O were obtained at different strain rates. Uniaxial tensile tests showed significant strain-rate sensitivity in all three material orientations (RD, DD, and TD) for DP600 and TRIP780. In contrast, AA5182- O exhibits almost near-zero strain-rate sensitivity. Several anisotropic yield functions were calibrated at various strain rates to evaluate the effect of strain rate on the flow surface shape. By comparing the quasistatic and updated flow surfaces of DP600 and TRIP780 predicted by Yld2000-2d, results show a relatively considerable effect of updating anisotropy coefficients for higher strain rates ( ). Several rate-dependent anisotropic material models (plane stress and general) were developed, by combining updated anisotropic yield functions and a rate-dependent hardening model (KHL). The developed models were implemented as user-defined material subroutines (VUMATs) based on implicit stress integration algorithm for ABAQUS/Explicit code to simulate electrohydraulic free-forming (EHFF) and die-forming (EHDF) processes. EHF simulations were completed, using Eulerian elements and ignition-and-growth model. The EHFF process was simulated for four different geometries (representing four different strain paths). Also, the EHDF process was simulated using a conical die The EHFF simulation results for the DP600 biaxial specimen showed that von Mises predicts a maximum effective plastic strain around greater than Yld2000-2d for the same amount of applied energy. The EHDF simulation result for DP600 showed that with the same applied energy magnitude, von Mises overpredicts major, minor and through-thickness shear strains and consequently effective plastic strain ( higher) compared to Yld2004-18p. Results showed that of the effective plastic strain occurs under a proportional biaxial strain path before contacting the die. Also, results showed that von Mises overpredicts maximum absolute compressive through- thickness stress and shear strain compared to the values predicted by Yld2004-18p. iv Acknowledgements I would like to acknowledge my dear advisor, Dr. Daniel Green who substantially helped and guided me to complete this work. Dr. Green; I would like to say it was a great opportunity for me to work with you and I really appreciate all your great support throughout the duration of this work. I would also like to express my gratitude to my best friend/colleague, Chris Maris for his kind and unbelievable support and assistance. Chris; I was very lucky to have such a nice and mature friend as at the desk next to mine. I would like to express my appreciation to Dr. Sergey Golovashchenko who technically guided me during this project. His expertise and knowledge was really amazing and I learnt a lot from him. I would also like to thank my favorite professor, Dr. William Altenhof, who always generously contributed his exceptional knowledge and expertise to me and our team. And finally, I would like to express my warm gratitude to my beloved wife, MONA, for her patience and understanding throughout the duration of this work. v Table of Contents Declaration of Previous Publication ................................................................. iii Abstract ............................................................................................................... iv Acknowledgements ............................................................................................. v List of Tables ....................................................................................................... x List of Figures .................................................................................................... xii 1 Introduction .................................................................................................. 1 2 Literature Review ......................................................................................... 7 2.1 Introduction ...................................................................................................... 7 2.2 High speed metal forming ................................................................................ 8 2.2.1 High strain rate metal forming processes ............................................................. 8 2.2.2 Electrohydraulic forming (EHF) ........................................................................ 11 2.3 Constitutive model .......................................................................................... 15 2.3.1 Anisotropic yield functions ................................................................................ 16 2.3.2 Flow rule ...........................................................................................................
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