Finite element simulation of SMA microactuators with large deflection

Abstract
For finite element simulation of shape memory actuators, a two-phase macromodel combined with a large deflection procedure is implemented in a FEM program for 3D mechanical analysis. The program is part of a tool for coupled electrical, thermal and mechanical problems. Details of the solution procedure are discussed. The model is used to investigate the performance of a shape memory alloy (SMA) microgripper. The microgripper is made of a monolithic SMA device of 2 x 5.8 x 0.1 mm ³ size comprising various integrated functional units like two microactuators for active closing and opening the gripping jaws and an optical slit. The simulated results are in quantitative agreement with experimentally determined data.