Fatigue on shape memory alloys: Experimental observations and constitutive modeling
Vanderson M. Dornelas, Sérgio Almeida de Oliveira, Marcelo A. Savi, Pedro Manuel Calas Lopes Pacheco, Luís Felipe Guimarães de Souza
Abstract
This paper deals with the fatigue of shape memory alloys considering both experimental and theoretical approaches. Initially, experimental tests are performed considering NiTi pseudoelastic wires subjected to different load conditions. Functional and structural fatigue are investigated considering situations related to phase transformations and plastic behavior. Afterward, experimental macroscopic observations are employed to propose a three-dimensional constitutive model to describe the general thermomechanical behavior of shape memory alloys, including functional and structural fatigue with a continuum damage perspective. An equivalent critical damage is proposed in order to define the fatigue life of shape memory alloys, considering different behaviors of martensitic and austenitic phases. Numerical simulations are compared with experimental data showing the capabilities of the proposed model. Results show that the model responses are in close agreement with experimental data, including fatigue life predictions.