Evaluating Fracture Energy Predictions Using Phase-Field and Gradient-Enhanced Damage Models for Elastomers

Abstract

For a large fraction of the computational engineering community, the phase field method has been the modus operandi for fracture simulations of engineering materials. The reason is mainly due to the simplicity of how the phase-field method handles complex crack propagation paths. Moreover, the phase-field approach has been subject to significant verification and validation efforts in the context of fracture of brittle linear elastic materials. More recently, the phase-field method has been extensively used for brittle fracture in soft materials including polymers, elastomers, and biological tissues. This study investigates the energy release rate due to crack propagation in hyperelastic nearly-incompressible materials – with a response reminiscent of elastomers – and compares the phase-field method and a novel gradient-enhanced damage (GED) approach. First, we simulate unstable loading scenarios using the phase-field method, which leads to convergence issues for the solver. To address the convergence issues, we introduce artificial viscosity to stabilize the problem and analyze its impact on the energy release rate utilizing a domain J-integral approach giving quantitative measurements during crack propagation. In the second part of the paper, we introduce a novel stretch-based GED model as an alternative to the phase-field method for modeling crack evolution in elastomers.