A numerical study on crack closure using a combination of self-healing microcapsules and shape memory alloy wires

Self-healing materials can be used as one of the types of smart materials in recovering and repairing equipment and preventing breakdown and fracture of tools. There are several ways to increase the efficiency and repeatability of the self-healing process, one of which is to combine self-healing microcapsules with shape memory alloys. Although several laboratory studies have been performed in this field, this method has not been given the attention it deserves. In this study, an attempt has been made to evaluate the performance of this compound using the finite element simulation method. For this purpose, used glass microcapsule and Ni-Ti SMA within the concrete matrix. After examining the results, the effect of shape memory alloy wires on increasing the maximum fracture stress was quite obvious. By adding two shape memory wires, the fracture tension has increased from 1.93 MPa to 2.08 MPa. Also, the most important effect is to close the crack opening distance in such a way that using two shape memory wires, the distance of the crack opening has decreased from 5 μm to 0.008 μm. Then, the effect of radius of memory alloy wires and thickness ratio and volume fraction of microcapsules on ultimate fracture stress and self-healing performance was investigated. Finally, the effect of interface strength on microcapsule fracture and ultimate fracture stress is evaluated.