Comparative Studies of Work-developing Capacity of Shape Memory Alloys (SMA) and Polymers

Abstract

The thermodynamic and work-generating behaviours of a Cu-14.86 Zn-5.81 Al (mass. %) shape memory alloy (SMA) and a three-layer PET heat shrinkable sheath were comparatively discussed. The experimental CuZnAl SMA under study experienced a reversible martensitic transformation and was able to lift over 4.8 mm, during heating-cooling cycles, a load which was 463 times heavier than the specimen. During heating, the PET fragments underwent up to three glass transitions and the PET ring-shaped specimens were able to lift over 3 mm, a load which was 1571 times heavier. By comparing the work generating capacity of CuZnAl SMA and PET heat shrinkable sheath, defined as the ratio between total absorbed enthalpy and specific work output, it was found out that the former has been ten times less effective than the latter. Keywords: shape memory alloy, heat-shrinkable sheath, work-generating shape memory effect, martensitic transformation, glass transition