Consideration of Orientation Properties of Short Fiber Reinforced Polymers within Early Design Steps

Abstract Within the modern automotive industry there is an increasing application of parts made of short fiber reinforced polymers (SFRP). The reasons are their beneficial mechanical properties and their series production capability. However, the prediction of their crash behavior by simulation is very complicated, since a precise simulation requires considering the fiber orientation distribution. That’s why, in early design steps often only imprecise, isotropic simulation approaches are deployed in order to save calculation time and license costs for additional software tools. The aim of the present paper is to introduce a simplified simulation approach allowing an anisotropic simulation taking into account the orientation data obtained by an injection molding simulation. To ena ble its application in ®early design steps only standard functions already implemented in LS-DYNA are deployed. The complex material behavior of short fiber reinforced polymers is represented by overlapping two standard material models of LS-DYNA in one single shell definition. The input parameters of the resulting phenomenological material description are obtained by using optimization methods. The methodology being used to convert the orientation data in order to set up an executable input deck is supported by two self-developed software tools. The first software tool extracts the orientation angles from the process simulation by assigning fiber orientation tensors to corresponding shell elements of the mesh of the crash simulation. For each shell element the orientation data are averaged and projected on the shell. By doing so, the complex orientation state is reduced to just three values per shell element – one fiber orientation angle and two fiber orientation probability values. Based on these data, the second software tool creates the executable input deck. The legitimacy of the presented approach is proved by an experimental validation: SFRP-plates are analyzed within a drop weight test. Despite the mentioned simplification (reduction of the complexity of the orientation state) the numerical results show a strong correlation with the experimental data.