The Three-Dimension Constitutive Model Of SMA

As a new intelligent material, shape memory alloy (SMA) is widely used and plays more and more important role in different fields such as construction engineering, detection, medical treatment, energy and mechanical engineering.As one of the absorbable materials, SMA is characterized in shape memory effect (SME) and pseudo-elasticity, which occur in different temperature ranges, caused by martensite phase transformation and orientation rearrangement. SMA is the effect when the temperature is lower than that at the end of inverse martensite phase transformation, SMA transforms under external loads, residual transformation occurs and SMA will return to the initial situation under high temperature when the temperature exceeds the phase transformation temperature, as if it can remember the initial temperature. PE is the effect that, when the temperature is higher than inverse martensite ending temperature, the non-elastic strain caused by SMA under external loads will disappear after unloading.The key point in the investigation of SMA lies in the description of the constitutive equation. In the present paper, a new SMA constitutive model is given based on plasticity theory by the systematical summarization of SMA constitutive equations presented nowadays.Because of the finite transformation characterization, with the application of finite element method on the calculation of unilateral tension and torsion, which prove the constitutive model is reasonable. It will provide theoretical foundation for the further investigation on the description of SMA by finite and plastic transformation.