A constitutive model for cyclic actuation of high-temperature shape memory alloys

In this work, a three dimensional constitutive model for High Temperature Shape Memory Alloys (HTSMAs) is presented. To describe the evolution of the cyclic actuation behavior of such alloys, viscoplastic mechanisms and transformation induced plasticity are introduced in addition to the classical transformation behavior of shape memory alloys. Based on continuum thermodynamics, the evolution of phase transformation, plasticity induced transformation, retained martensite and viscoplasticity are described. Deformation mechanisms that occur over the operational range of such HTSMAs have been identified from the thermomechanical behavior of a NiTiPd alloy. The proposed model has therefore been calibrated and validated based on the thermomechanical response of the studied NiTiPd HTSMA alloy during thermal cycles under compression. Careful attention is devoted to the calibration procedure to identify the contribution of the different mechanisms independently. Finite Element Analysis (FEA) is performed to demonstrate the capabilities of the model to describe the cyclic behavior of HTSMA devices. (C) 2013 Elsevier Ltd. All rights reserved.