熱・力学的繰返し条件下におけるTi-Ni-Cu形状記憶合金の疲労寿命

概要

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The shape memory alloy with the shape memory and superelastic functions has been used for many applications such as actuators, sensors, and so on. In order to undertake reliable engineering designs and optimum material selection, it is important to clarify the fatigue lives of shape memory alloy under thermal and mechanical cycles. In this paper, the fatigue lives of Ti-41.7 at% Ni-8.5 at% Cu alloy are investigated experimentally. Experiments are carried out by repeating the combination of the thermal cycle and the loading-unloading cycle. And the variations of the recovery stress, the irrecoverable strain and the recovery strain energy with cycles are investigated for various heating temperatures and strains. Furthermore, the fatigue lives for various heating temperatures and strains are investigated, and fractured surfaces are observed by SEM. Results show that the fatigue lives are divided into three regions according to the maximum strain and depend upon heating temperature. It is also noted that the fatigue lives can be estimated in relation to the dispersion strain energy obtained by the amount of decrease of recovery strain energy per cycle.
2000-04-25