A procedure for the simulation of failure in thermoplastic composites

Crash simulation with engineering composites like “glass mat reinforced thermoplastic” (GMT) is still a challenging task, mainly because these materials soften when their ultimate strength is exceeded. This causes the localization of strain, an instability that can only be modeled with finite elements when some kind of regularization technique is applied. This paper addresses the problem of regularization as well as some other relevant problems that occur when the crash of parts built from randomly reinforced plastics such as GMT have to be simulated. Pragmatic solutions are presented and combined to form a procedure for the simulation of the dynamic failure of GMT components consisting of four steps: a regularization technique to prevent the mesh dependence of the simulation results, a way to account for the scatter in the material properties of these materials, a simple representation of the strain rate dependence of the material properties and finally some instructions for the modeling of all relevant details of the geometry of the crashed structure. The final comparison of the results of pre-test simulations with the results of crash tests shows a good correspondence and therefore confirms the proposed approach.