Reversible Deformation of NiTi Spring Actuators under Constant External Counteraction

The laws of changing the shape of cylindrical springs made of a titanium nickelide-based alloy are considered as a function of the level of counteracting stresses and thermal cycling boundaries. Stresses from 20 to 110 MPa are shown to cause completely reversible deformation of the material; at higher stresses, unrecovered deformation accumulates. During thermal cycling, a decrease in heating temperatures in the range A_s–A_f and an increase in cooling temperatures in the range M_s–M_f are accompanied by a decrease in the reversible deformation of the material.