Abstract
Uniaxial tensile tests on Ti-Ni alloy wire under cyclic loading and unloading were carried out. The influences of maximum strain, test temperature, and shape memory processing temperature upon the cyclic characteristics of pseudoelasticity were examined. The results obtained are summarized as follows. (1) Starting stress of stress-induced martensitic transformation decreases with the number of cycles. The rate of decrease takes an almost constant value without depending on the test temperature and maximum strain. (2) In the region of stress-induced martensitic transformation, residual strain in each cycle increases with test temperature. (3) The change of strain energy per unit volume for the number of cycles becomes larger in the order, dissipated strain energy, total strain energy, and recoverable strain energy. (4) Yield stresses of stress-induced martensitic transformation and reverse transformation decrease with the shape memory processing temperature. (5) The transformation strain range at each 1OOth cycle takes a maximum value at a certain shape memory processing temperature. (6) Every characteristic value of pseudoelasticity varies significantly in the early cycles, but becomes stable after these cycles.
