Shape memory alloys-polymer composites: Interfacial strength under mechanical and thermal loading

This work reports results of preliminary investigations of an R&D project on shape memory alloy-based composites with shape morphing capabilities to be used as active aerodynamic components in automotive. The work addresses a major issue for SMA-polymer integration, that is the limited interfacial strength between metals and polymers. In particular, pull-out tests of SMA-polymer samples were carried out under different thermo-mechanical loading conditions with the aim of understanding the effect of mechanical stress and thermal activation on the shear strength between SMA wire and embedding resin. To this aim, three different pull-out experiments were carried out: i) mechanical test of as manufactured samples, ii) mechanical tests after cyclic thermal activation of the sample and iii) pull-out test during the activation of the SMA wire. The aim is to understand the influence of the mechanical and thermal stresses as well as their combination on the interfacial strength of SMA/polymer samples. Results revealed that, for the investigated resin, thermal stresses and temperature during thermal activation represent the most responsible of delamination mechanisms.