An experimental and numerical crashworthiness investigation of thermoplastic composite crash boxes

Dynamic crash tests are performed in order to determine the crash behavior of thermoplastic composite crash boxes. The specimens are made from woven fiberglass/polyamide plates. Recently developed thermoforming and welding methods are used to construct the crash boxes. The crash experiments show that the tubes are crushed in progressive manner start from one end of the tubes and delamination takes place between the layers. To better understand details of the crash process, the LS-DYNA explicit finite element code is used. Thin shell elements are used to model the walls of the crash box. To simulate the delamination between the composite layers, the tube walls are modeled as multi layer shell elements. An adequate contact algorithm is implemented to model the adhesion between the layers. Finally the multi design optimization MDO technique is implemented to find an optimum composite crash box that absorbs the most energy and has minimum weight. The crash performance of the optimum composite crash box is compared with an optimum aluminum tube.