A cohesive elements based model to describe fracture and cohesive healing in elastomers

Abstract

Several polymeric systems with intrinsic Self-Healing (SH) capabilities have been reported in literature. Many of them showed healing upon contact across the crack interface. Different parameters such as contact time, temperature, pressure or chemical activity determine the degree of healing obtained. In this work, a numerical simulation of the healing efficiency as a function of the environment is proposed based on the use of cohesive elements in a finite element model. Cohesive elements are commonly used to model interlaminar fracture mechanisms in composite materials. In this work, they are adopted to simulate both failure and subsequent healing by a specific SH elastomeric system. The SH elastomeric system is initially characterised by means of the identification of its conventional mechanical properties. From these results, a hyperelastic constitutive model is selected. At the same time, a model simulating fracture mechanics and healing mechanics is established and validated using a cohesive failure model in a commercial explicit finite element code. Finally, the two models are combined to evaluate the capability of the proposed numerical approach to simulate: (i) the restoration of contact of the two separated sides of the material during their rejoining, and (ii) the restoration of the mechanical properties of the elastomeric system. This later stage is directly linked to the healing efficiency. While the model does not yet capture all features of healing, it offers attractive features worth further exploring also for other SH systems.