A Systematic Approach to Performance Evaluation of Shape Memory Alloys as Actuator Material

Abstract

This work presents a combined performance evaluation approach for SMAs as actuator material – an approach based on the combination of three testing modes: a) stress-free thermal recovery mode, b) fixed-support stress generation mode and c) constant (or variable) bias-stress recovery mode. Based on this testing, a so-called “design diagram” can be constructed. This diagram demonstrates the mechanical work generation potential of an SMA and therefore represents a must-have tool for the application engineer. Given that the working envelope depends on the material composition, microstructure and number of actuation cycles, this approach allows the selection of an appropriate material and the processing technique that will meet the functional requirements of a specific application. To illustrate the proposed performance evaluation technique, we show how it can be applied to the design of an SMA actuator for a morphing wing.