Tailored processing of epoxy with embedded shape memory alloy (SMA) wires

We present the development of a low-temperature liquid composite moulding cure schedule that is compatible with the fabrication of shape memory alloy (SMA)–epoxy composite materials. With this process, the SMA wires do not need to be maintained in place with an external frame, even though the peak post-cure temperature exceeds the activation temperature of the SMA wires. The intrinsic interfacial shear strength of the final material is experimentally determined from single wire pull-out tests, and is compared with the shear stress exerted at the interface by an activated SMA wire. These measurements show that the interface is strong enough to withstand the maximum activation stress. This is confirmed through tests involving the cyclic activation of SMA wires embedded in epoxy samples. The paper successfully demonstrates that, by careful tailoring of the processing schedule, an SMA–epoxy composite that maintains a strong interfacial bond during both processing and subsequent activation of the embedded wires can be fabricated using standard composite processing methods.