The Durability of "Smart" Composites Containing Shape-Memory Alloy Actuators

Smart Materials Group, Cranfield University, Shrivenham Campus, Swindon, England

Abstract

This paper presents the results from an experimental study into the actuation response of laminates containing Shape-Memory Alloy (SMA) actuators. Unidirectional glass-fibre reinforced epoxide laminates were constructed containing Ni-Ti SMA actuators orientated parallel to the glass-fibre direction. Two volume fractions of actuator were employed (0.5 and 1 vol%) with actuation strain levels of 2 and 5%. These laminates were designed to exhibit a macroscopic shape change during electrical activation of the SMA. This work has addressed a major durability issue associated with the operation of such laminates. This is the instability in both shape and deflection which occurs during the early operational cycles. It is shown that such changes depend critically on the initial shape-memory training of the actuators during manufacture, and on the subsequent in-situ retraining of the memory effect within the embedded SMA.