From rheological to original three-dimensional mechanical modelling of semi-crystalline polymers: Application to a wide strain rate range and large deformation of Ultra-High Molecular Weight PolyEthylene

Ultra-High Molecular Weight semi-crystalline polymers, such as Ultra-High Molecular Weight PolyEthylene (UHMWPE) exhibit strong wear and impact resistance, making them good candidates for structural applications in many industrial fields. At high strain rate and large strain, mechanisms of deformation are quite different from those involved in classical semi-crystalline polymers, mainly because chain disentanglements are almost impossible for very long macromolecules even at temperature far above the melting point. Thus, there is a need to develop specific models for these materials and, from the works of Deplancke and her co-workers (Deplancke et al., 2019; Deplancke et al., 2015) who developed a scalar description based on polymer physics, three-dimensional constitutive equations are developed in this work. The developed model proposes an innovative way to take into account the repartition of strain for a semi-crystalline polymer and more generally for a two-phase material. Moreover, by modelling the evolution of microstructure during the plastic deformation of the material, the model is able to reproduce quite fairly the mechanical behavior of UHMWPE for both loading and unloading.