A numerical model to simulate the deformation and fracture of polyethylene fibres

Abstract

A model was developed to simulate the mechanical behaviour of ideal polyethylene (PE) fibres made up of an ordered network of PE molecules of finite molecular weight completely extended and oriented along the fibre axis. The fibre was represented by a two-dimensional lattice, the nodes being linked by elastic rods which could carry normal and shear forces and stood for the intrachain covalent bonds and the interchain van der Waals forces. Fibre deformation was simulated incrementally, and the stresses on the bonds after each deformation step were computed with a numerical algorithm, which was also used to re-establish the mechanical equilibrium after bond rupture, that was introduced by the kinetic theory of fracture and a Monte Carlo lottery. Using appropriate values for the bond properties (stiffness, activation energy, etc), the effect of molecular weight, strain rate and temperature on the tensile behaviour and on the deformation micromechanisms of PE fibres was studied. The good qualitative agreement with the experimental data, regardless of the simplicity of the fibre model, indicated the excellent potential of these discrete models to simulate the deformation of polymeric fibres.