Numerical modeling and analysis for axial compressive crushing of randomly oriented thermoplastic composite tubes based on the out-of-plane damage mechanism

Abstract The structural beams with a uniform cross section of hat-shape were manufactured through a high-cycle compression molding technique, by using randomly oriented chopped thermoplastic composites. The crash tubes were obtained by vibration welding of those two hat-section beams at their flanges. And the axial compressive impact tests were carried out for them. It followed that the compressive failure was progressive crushing caused by the delamination and local buckling of walls and welded flange while the specific energy absorption was so high. The finite element model was constructed to predict the axial progressive crushing and energy absorption. The important key concept for designing the numerical model was to incorporate some hypothetical inter-layers even in randomly oriented composites and assign them with the failure model as cohesive zone elements, which can perform non-linear characteristics with failure criterion. The material parameters for the model tried to be obtained by direct measurement test methods. The reproducibility of the numerical modeling was validated against the results from axial compressive crushing. The progressive damage mode and energy absorption prediction agreed well with the experimental results. It was also clarified that the out-of-plane failure influenced the energy absorption performance of the crash tubes.