Shape memory effect on interfacial strength of SMA-reinforced composites

Shape memory alloys (SMAs), when in the form of wires or short fibers, can be embedded into a host material to form SMA-composites for satisfying a wide variety of engineering requirements. Recovery action of SMA inclusions induced by elevated temperature can change the modal properties and hence the mechanical responses of the whole composite structure. However there is a lack of experimental [mdings on the interfacial behavior of this 'novel' material system, which governs the mechanical limitation of composite structures. Therefore, the principal aim of this paper is to study the shape memory effect (SME) on interfacial strength of SMA composites and validate the previously developed theoretical model for the prediction of interfacial debond using the SMA wire pullout test. The embedded wires were subjected to electrical resistive heating for SME generation inside the epoxy matrix cylinder. Stress-displacement results were obtained and the debonding processes were closely monitored and recorded by using a high-resolution digital video camera. Results for different actuation temperatures were analyzed systematically and compared with the theoretical solutions of partial debond stresses under SMA actuation. The generally good agreement between experimental findings and theoretical results convinced the application of the new developed model for the prediction of interfacial strength, which is crucial for fully utilizing the SME inside a composite without destroying the interface during actuation.