Numerical implementation of a damage-coupled material law for semicrystalline polyethylene

Purpose - The purpose of this paper is to provide a computational procedure for a novel damage-coupled material law for semicrystalline polyethylene. Using a damage mechanics approach, the model seeks to gain insight into the mechanical behaviour of polyethylene considering the microstructure and degradation processes occurring under uniaxial tension. Design/methodology/approach - The material morphology is modelled as a collection of inclusions. Each inclusion consists of crystalline material lying in a thin lamella attached to an amorphous layer. The interface region interconnecting the two phases is the plane through which loads are carried and transferred by the tie molecules. It is assumed that the constitutive model contains complete information about the mechanical behaviour and degradation processes of each constituent. After modelling the two phases independently, the inclusion behaviour is found by applying some compatibility and equilibrium restrictions along the interface plane. Findings - The model provides a rational representation of the damage process of the intermolecular bonds holding crystals and of the tie-molecules connecting neighbouring crystallites. The model is also used to analyze the degree of relationship between some of the material properties and the mechanical responses. Practical implications - In practice, the numerical model clearly helps to understand the influence of the different microstructure properties on the tensile mechanical behaviour of semicrystalline polyethylene - an issue of particular interest in improving material processability and product performance. Originality/value - To the authors' knowledge, a phenomenon such as microstructural degradation of polyethylene has not received much attention in the literature. The proposed model successfully captures aspects of the material behaviour considering crystal fragmentation and tie-molecule rupture.