Non-medical applications of shape memory alloys

The diversity of (potential) applications using shape memory alloys (SMA), apart from the medical field, becomes quite large. Classic categories such as free recovery, actuators, constrained recovery, pseudo-elasticity or damping require further specifications. For example, micro-actuators. smart materials or active damping, can be all classified as actuator applications, but each of those items demands specific functional performance, dimensions and processing. Furthermore, success for applications can only be realised in so far those materials offer also a price-competitive advantage relative to other functional materials or mechanical designs. This competition requires perfect control of the material performance. It is known that especially Ni-Ti alloys can be tuned relatively easy to some specific requirements of the envisaged application: hysteresis, transformation temperatures, damping capacity. At the other side little is known on recovery stresses, wear resistance, fracture mechanics, fatigue... In this paper we would like to stress the need for further exploration of the 4P-relation: principles-properties-processing-products as well in companies as in universities or other research laboratories. This will be illustrated by describing some actual applications indicating why they are successful, other applications why they failed and still others that can only be realised if some further, probably possible. material improvement can be realised. (C) 1999 Elsevier Science S.A. All rights reserved.