Modeling of Functional Properties of Porous Shape Memory Alloy

Abstract

Abstract.A model accounting for the microstructure of porous TiNi shape memory alloy samples fabricated by selfpropagating high temperature synthesis has been proposed for simulation of their functional-mechanical properties. Structural elements of a porous sample have been approximated by curved beams. An analysis of shapes and sizes of pores and ligaments permitted to identify characteristic sizes of the beams. A mathematical object consisting of rigidly connected small curve beams has been considered. The stress-strain state of a beam was estimated by the classical methods of strength of materials. The microstructural model was used for calculation of the phase deformation of the shape memory material. Simulation of stress-strain curves and phase deformation of a porous TiNi sample on cooling and heating under a constant stress has shown a good correspondence between the experimental data and the results of modeling.

Model for simulation of the mechanical behavior of a porous shape memory alloy with a non-ordered structure

“…where R i and φ i are the radius and central angle of the vertical curved beam before deformation, R i ' and φ i ' are the radius and central angle after deformation, ε i is the maximum strain in the curved vertical beam. The dependences R i '(ε i ) and φ i '(ε i ) were also derived [16] within the frames of the hypotheses (1) and 2:…”