Based on the micromechanical method and thermodynamic theory,a constitutive model for the macroscopic mechanical behavior of porous NiTi shape memory alloy is presented.The hydrostatic stress is considered for porous NiTi according to the transformation function of dense NiTi.The present model takes account of the tensile-compressive asymmetry of NiTi,and can degenerate to model dense material.Numerical calculations,which only need material parameters of dense NiTi,are conducted to investigate the nonlinear and hysteretic strain of porous NiTi,and the predicted results are in good agreement with the corresponding experiments.
