Development of a graph and heuristic based method for the topology optimization of crashworthiness profile structures
Passive safety is one of the dominant design criteria in the development of a vehicle. It includes safety measures which mitigate the consequences of an accident for vehicle occupants and other road users after an accident has become inevitable. A core element of the passive safety is the vehicle body. The tool of the topology optimization could make a valuable contribution here. For linear static loaded structures there exist a number of efficient methods for topology optimization. However, they cannot be used for crashworthiness structures due to the occurring nonlinearities and the dynamics. The nonlinearities are large displacements and rotations, contact phenomena, as well as plastic and rate-dependent material behavior. Further difficulties arising in an optimization with consideration of crash load cases are bifurcation points, a high number of local optima and the impossibility to determine the sensitivities analytically and therefore without additional function calls. In this work the Graph and Heuristic Based Topology Optimization (GHT) is presented which addresses these difficulties and can be used for the topology optimization of profile cross sections of crashworthiness structures. In the GHT the actual optimization problem is divided into two optimization loops convoluted in each other. In the outer optimization loop heuristics derived from expert knowledge change the topology of the structure to be optimized, based on simulation data from crash simulations. In the inner optimization loop conventional universal optimization algorithms for the shape and sizing optimization of the structure are used. The geometry of the structure to be optimized is described by a mathematical graph. The graph is generated according to a specially for this purpose developed syntax and also allows complex geometric modifications such as topology changes by the flexible description of the geometry. Graph based algorithms are used for the check of manufacturing constraints.
Shaker Verlag, ISBN: 978-3-8440-3746-3
