Nonlinear model accounting for minor hysteresis of embedded SMA actuators

Abstract

A quantitative index martensite fraction was used to describe the phase transformation degree of shape memory alloy (SMA). On the basis of the martensite fraction, a non-linear analysis model for major and minor hysteresis loops was developed. The model adopted two exponential equations to calculate the martensite fractions for cooling and heating, respectively. The martensite fractions were derived as the relative parameters were adjusted timely according to continuous, common initial and common limit constraints. By use of the linear relationship between the curvature of embedded SMA actuator and SMA s martensite fraction, the curvature was determined. The results of the simulations and experiments prove the validity and veracity of the model.