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John E. Renaud Professor Aerospace and Mechanical Engineering • Research Areas • Publications |
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Hybrid Cellular Automata: a biologically-inspired
structural optimization technique Structural adaptation models of living organisms can be used to solve topology optimization problems in engineering applications. This work presents a new approach for obtaining optimal topologies in continuum structures. The approach is referred to as the hybrid cellular automaton (HCA) method. The development of the HCA methodology has been inspired by the biological process of bone remodeling. The HCA method divides the design domain into a lattice of cellular automata (CAs). Locally, each CA is able to modify a continuum structural design variable based on the strain energy level in its neighborhood. A global structural analysis, using the finite element method, is used to obtain the strain energy information during each iteration. The local change in the design variable (i.e., density) is determined by a local design rule. The design rule drives the strain energy level towards a target point using a closed-loop control strategy. The controllers developed in this work include two-position, proportional, derivative and integral control. In more recent efforts, the hybrid cellular automaton (HCA) method for structural synthesis has been extended to facilitate simultaneous topology and shape optimization. The HCA methodology has been developed for application to continuum structures. In bone remodeling, only those elements located on the surface of the mineralized structure can be modified. In the HCA methodology implemented in this research only surface elements are allowed to change density during the structural synthesis process. Closed-loop control is used to modify the mass distribution on the internal and external surfaces of the design domain to find an optimum structure. The local control maintains a balance between mass and rigidity. The new methodology effectively combines elements of topology optimization and shape optimization into a single tool. |
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| Tovar, A., Patel, N., Niebur, G.L.,
Sen, M., Renaud, J.E., "Topology Optimization Using a Hybrid
Cellular Automaton Method With Local Control Rules", ASME
Journal of Mechanical Design. (in press) Tovar, A, Gano, S.E., Mason, J.J., Renaud, J.E., 2005, "Optimum Design of an Interbody Implant for Lumbar Spine Fixation", Advances in Engineering Software, Volume 36, Issue 9, pp. 634-642, September, Published by Elsevier Science, The Netherlands. Zhou, Y., Li, C., Renaud, J.E., Mason, J.J., 2005, "Improvement of Mechanical Properties of Bone Cement by Shape Optimization of Short Fibers", Engineering Optimization, Volume 37 (2), March , pp. 121-134, Published by Taylor & Francis. Tovar, A., Patel, N., Letona, G., Kaushik, A., Sanders, B., Renaud, J.E., 2004, "Hybrid Cellular Automata: A Biological Inspired Structural Optimization Technique", AIAA-2004-4558, Proceedings of the 10th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, Albany, NY, August 30-September 1. Tovar, A., Niebur, G.L., Sen, M., Sanders, B., Renaud, J.E., 2004, "Bone Structure Adaptation as a Cellular Automaton Optimization Process", AIAA 2004-1914, pp. 1-14, Proceedings of the 45th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, Palm Springs, CA, April 19-22. |
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