Non-associated viscoplasticity coupled with an integral-type nonlocal damage model for mineral filled semi-crystalline polymers

• Non-associated viscoplastic model coupled with nonlocal damage at finite strains for mineral filled semi-crystalline polymers.
• Model able to reproduce the non-isochoric deformation with mesh-independent results despite of the strain-softening.
• Hypoelastic formulation using the logarithmic corotational integration of the stretching tensor.
• Implementation of the nonlocal formulation in a commercial finite element code achieved in a simple manner.
• Mesh independent results arising from finite elements simulation close to experiment in term of local strain evolution.

A non-associated viscoplastic model coupled with nonlocal damage under finite strain framework is developed to simulate the non-isochoric deformation and the damage process exhibiting strain-softening of a 20% mineral filled semi-crystalline polymer. The logarithmic spin tensor properties linking the Eulerian Hencky strain with the Cauchy stress is used thanks to hypoelasticity assuming the additive decomposition of the stretching into elastic and viscoplastic parts. The constitutive model with its nonlocal formulation is implemented in an efficient manner in a commercial implicit finite element code. The proposed model exhibits mesh-independent responses and is in agreement with strain evolution observed experimentally.