抄録
The shape memory alloy with the shape memory and superelastic functions has been used for many applications. Authors have proposed a reciprocating heat engine incorporating, as an energy conversion element, shape memory alloy wires. In order to undertake reliable engineering designs and optimum material selection, it is important to clarify the thermo-mechanical properties such as functions and fatigue characteristics. In this paper, the effect of heating temperature and deformation strain on the strain energy and the thermal efficiency of Ti-Ni-Cu shape memory alloy is investigated experimentally. Experiments are carried out by repeating the combination of the thermal cycle and the loading-unloading cycle. Results show that the available strain energy per cycle is insensitive to heating temperature in the low strain range. However, when the deformation strain is larger than 2%, the available strain energy shows a heating temperature sensitivity. It is also mentioned that the degradation of available strain energy shows a heating temperature and increases with increasing in heating temperature. But it is insensitive to the deformation strain. Furthermore, the total available strain energy to failure becomes maximum in the vicinity of 5% strain in every temperature region, and increases with the decrease in heating temperature. The energy conversion efficiency is about 1.2% under the conditions which maximize the total available strain energy.
