Multi-Material Topology Optimization for Crashworthiness Using Hybrid Cellular Automata

Structures with multiple materials have now become one of the perceived necessities for automotive industry to address vehicle design requirements such as light-weight, safety, and cost. The objective of this study is to develop a design methodology for multi-material structures accountable for vehicle crash durability. The heuristic topology synthesis approach of Hybrid Cellular Automaton (HCA) framework is implemented to generate multi-material structures with the constraint on the volume fraction of the final design. The HCA framework is integrated with ordered-SIMP (solid isotropic material with penalization) interpolation, artificial material library, as well as statistical analysis of material distribution data to ensure a smooth transition between multiple practical materials during the topology synthesis. Since the proposed method does not rely on additional variables to represent material selection, the computational cost of this method is independent of the number of the phases in a multi-material design. The dynamic simulations of a sphere ball impacting an armor plate and the frontal crash on a car bumper are used to evaluate the proposed multi-material topology synthesis algorithm. The practical materials are the different grades of steels with the same elastic properties and different yield strength and plastic hardening. The crash performance measures such as peak acceleration-displacement profiles of multi-material designs are compared with binary designs obtained from HCA to conclude the results of the multi-material HCA framework.