Theoretical and numerical limitations for the simulation of crack propagation in natural rubber components

In this paper, two commercial software packages dedicated to the simulation of crack propagation in elastomer components were tested: FLEXPAC and MSC-MARC. Firstly, the theoretical limitations of classical crack propagation laws were examined to demonstrate that actual numerical predictions are limited to very simple loading conditions. Secondly, crack propagation approaches implemented in both softwares were analysed. In order to compare their performances, fatigue experiments are performed. Different rubber components with different pre-cracks were tested under several loading conditions. Crack propagation, i.e. size and direction of the crack, was measured as a function of the number of cycles. Then, these results were compared with crack direction criteria proposed by the two models. It was demonstrated that loading amplitude highly influenced the crack direction and that the models must take this into account in their solver. Finally, limitations of this type of numerical analysis to predict the duration life of rubber components were highlighted.