Self-healing performance of a microcapsule-based structure reinforced with pre-strained shape memory alloy wires: 3-D FEM/XFEM modeling

Combination of microcapsules and shape memory alloys (SMAs) is one of the promising self-healing mechanisms. Although there are several parameters which affect the performance of such structures, limited studies are performed on this combined healing mechanism. In this work, we study the performance of such a composite structure using a 3-D finite element and extended finite element model consisting of matrix, glass microcapsule, healing agent, and Ni-Ti SMA wire. After examining the results, the effect of shape memory alloy wires on increasing the maximum fracture stress was observed. Moreover, the effect of radius of shape memory alloy wires, initial crack location, thickness ratio and volume fraction of microcapsules, and interface strength on ultimate fracture stress are investigated. Also, as a key parameter in self-healing performance, the crack opening distance decreased from 5 to 0.008 mu m using 0.5% volume fraction of shape memory wires without pre-strain. In the case that the wires have a pre-strain of 1%, this value reaches almost zero and a compressive stress is induced between fracture surfaces which can enhance the healing process and adherence of healing agent.