On the differential equation describing the hysteretic behavior of shape-memory alloys

An inelastic strain-temperature state equation describing the behavior of inelastic strain in shape memory alloys was obtained as a result of quantitative analysis of Ni--Ti state equations. Plate specimens of Nitinol (Ni sub 51 Ti sub 49 ) were used in the experiments. The load was applied at the middle point of the plate and the middle point displacement was measured in order to estimate the temperature behavior of inelastic strain caused by martensitic transformation. The data were normalized by unite value in the low temperature region. The differential equations derived were viewed as the most convenient way to quantitatively describe inelastic strain evolution with the temperature in shape memory alloys. In particular, the alloys may be represented as a general solution of these equations. In the small hysteresis case, the state equations are shown to be in agreement with the results of Cory and McNichols.