Parameter-based topology optimization for crashworthiness structures

Abstract Topology optimization methods like the homogenization method are very efficient for statically and dynamically loaded structures, but the use of these methods for the topology optimization of crashworthiness structures runs into a lot of problems. Especially in structural contact problems, the optimization functions are not smooth and the use of local sensitivity information is not successful. The basic of the optimization approach, which is presented in this paper, is the bubble method. The strategy of this method is an alternation of shape optimization and positioning of additional holes (bubbles). For the shape optimization, the geometry features are described by CAD parameters, so that the method works with a few design variables (e.g. less than 100 important variables for a whole automotive). The optimization process is supported by a highly flexible CAD tool, which is especially programmed for the concept development of automotives. This tool manages the CAD parameters in different hierarchical levels and generates an associated crash simulation model. The optimal position of a next hole is found with analytical positioning criteria or numerically with crash simulations of different hole positions by using e.g. design of experiment strategies and response surface models. The main focus of this contribution is to show the possibilities and the difficulties of the hole positioning strategies for different structures and different objectives and constraints. The application examples deal with functions like “deformation energy”, “maximal intrusion”, “maximal forces”, “maximal accelerations”, “HIC value”, and the weight of the structure.