Structural design for crashworthiness is a challenging area of research due to large plastic deformations and complex interactions among diverse components of the vehicle. Previous research in this field primarily focused on energy absorbing structures that utilize a desired amount of material. These structures have been shown to absorb a large amount of the kinetic energy generated during the crash event; however, the large plastic strains experienced can lead to failure. This research introduces a new strain-based topology optimization algorithm for crash-worthy structures undergoing large deformations. This technique makes use of the hybrid cellular automaton framework combining transient, non-linear finite-element analysis and local control rules acting on cells. The set of all cells defines the design domain. In the proposed algorithm, the design domain is dynamically divided into two sub-domains for different objectives, i.e., high strain sub-domain (HSSD) and low strain sub-domain (LSSD). The distribution of these sub-domains is determined by a plastic strain limit value. During the design process, the material is distributed within the LSSD following a fully-internal-energy-distribution principle. To accomplish that, each cell in the LSSD is driven to a prescribed target or set point value by modifying its stiffness. In the HSSD, the material is distributed to satisfy a failure criterion given by a maximum strain value. Results show that the new formulation and algorithm are suitable for practical applications. The case studies demonstrate the potential significance of the new capability developed for a wide range of engineering design problems.

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