Analytical modelling of functionally graded NiTi shape memory alloy plates under tensile loading and recovery of deformation upon heating

This paper presents an analytical model describing the deformation behaviour of functionally graded NiTi plates under tensile loading and their shape recovery during heating. The property gradient of the plate is achieved by either a compositional gradient or microstruc- tural gradient through the thickness. Closed-form solutions are obtained for nominal stress-strain variations of such plates under uni- axial loading at different deformation stages. It is observed that the martensitic transformation occurs partially over the nominal stress gradient, unlike typical NiTi shape memory alloys. The curvature-temperature relations are established for complex shape memory effect behaviour of such plates during the recovery period. The analytical solutions are validated with relevant experimental results.