NiTi-Based Shape Memory Actuators for Industrial Applications: Present Developments and Future Opportunities

Shape Memory Alloys (SMAs) are active metallic materials clas­sified nowadays as “smart” or “intelligent” materials along with piezoelectric ceramic and polymers, electro-active plastics, elec­tro-rheological and magneto-rheological fluids and others. These multifunctional materials are naturally considered as sensor-actuator elements demonstrating large possibilities for applications in high-tech smart systems. One of the main areas of interest is that of actuators. The use of SMAs in actuators offers an excellent technological opportunity to develop reliable, robust, simple and lightweight elements within structures or as stand-alone components that can represent an alternative to electro-magnetic actuators commonly used in several fields of industrial applications, such as automotive, appliances, consumer electronics and aerospace.

NiTi SMAs demonstrated to have the best combination of properties. Due to their relatively high recovery stress and strain, actuators providing significant force and displacement can be designed. There are perhaps thousands of applications of NiTi-based actuators mentioned in literature and in patents. However, only very few make it to larger quantity and can be found in recent products. Successful applications will build on SMA strengths while taking into account its weaknesses.

In this work a general overview about the peculiar behavior of NiTi alloys along with their main issues, the shape memory components under development and the role of modeling and simulation in the design will be presented and discussed. A bird’s-eye view on the future opportunities of NiTi-based shape memory actuators for industrial applications will also be given.