Analysis of Thermomechanical Behavior of Shape-Memory-Alloy Bimorph Microactuator

Shape-memory-alloy (SMA) has attracted considerable attention in recent years as a smart and efficient material due to their unique properties. SMA microactuators are recognized as one of the potential solutions for unresolved issues in the rapid development of micro electromechanical systems. This paper presents the study and analysis of thermomechanical behaviour of bimorph-SMA structure when parameters such as the thickness of SMA layer, the type of the stress layer and their thickness, and the processing temperature are changed. The analysis was performed using a finite element method. Materials such as SiO2, Si3N4, and Poly-Si are used as stress layer in these analyses to mimic the materials that can be deposited using Plasma Enhanced Chemical Vapor Deposition (PECVD) process. Results show that bimorph SMA structure achieves maximum displacement when SiO2 is used as stress layer. For a SMA structure with dimension of 10 mm (length) x 2 mm (width) x 50 µm (thickness), a maximum displacement of 1859 µm is achieved when 6 µm of Si3N4 layer deposited at temperature of 400 °C.