Computational study on a damage-coupled model for crystalline polyethylene
Purpose - The purpose of this paper is to formulate an algorithm for a novel damage-coupled material law for crystalline polyethylene at finite inelastic strains followed by investigation of the influence of the aggregate representation and material parameters on the material response. Design/methodology/approach - The constitutive equations are developed within the framework of continuum damage mechanics to describe crystal fragmentation caused by atomic debonding of the crystallographic planes. The material is assumed initially isotropic and homogeneous and is represented as an aggregate of randomly oriented crystals with an orthorhombic lattice. For the velocity gradient, an additive decomposition into symmetric and skew-symmetric components is applied, where the skew-symmetric part (spin) is decoupled from the lattice shear by means of a damage variable. Structural features such as lattice parameters and orientations, slip systems, and kinematic constraints are incorpo-rated. Findings - The proposed model is implemented to predict stress-strain behaviour under uniaxial tension and damage accumulation and texture development at the different stages of deformation. In the numerical examples, the effects of the aggregate size, crystal orientations, and material parameters on the model estimates are analyzed. Originality/value - The model used herein is a first attempt to analyze the influence of crystal fragmentation caused by the debonding of the crystallographic planes on the predicted mechanical behaviour and texture development of polyethylene prior to failure.
modelling crystallization algorithms polymers stress (materials)