Modeling of Superelastic–plastic Behavior of Porous Shape Memory Alloys Incorporating Void Shape Effects

A new constitutive model for describing the superelastic–plastic behavior of porous shape memory alloys(SMAs)is proposed.The model incorporates the influences of void shape and hydrostatic pressure as well as the elastic modulus mismatch between austenite and martensite.In addition,the interactions between plastic strain and transformation strain are considered via the plastic back stress.The porous SMAs are considered as two-phase composites with the dense SMA matrix and the second phase representing ellipsoidal voids.Based on Gurson’s formulation,the transformation and plastic flow potentials accounting for the transformation–plasticity coupling are developed.The numerical results present good agreement with available experimental data for various levels of porosity,which proves that the model is capable of capturing stress-induced phase transformation and plastic deformation of porous SMAs.Using the proposed model,the influence of plastic strain on reverse transformation and the effects of porosity and void shape on the pseudoelastic and plastic behavior of porous SMAs are investigated.