ON THE DAMPING BEHAVIOR OF NITI SHAPE-MEMORY ALLOY

Shape memory alloys exhibit a high damping capacity in the martensite state. Results obtained from both DMA and cyclic tests under tension-c ompression load show that the martensite damping capacity in NiTi SMAs is a function of both strain amplitude and annealing temperature. Int ernal friction due to movements of martensite twin boundaries within b oth elastic (accommodation) and inelastic (reorientation) ranges as a function of strain amplitude seems to be consistent. A critical anneal ing temperature exists for deformed NiTi SMAs in order to obtain a hig h martensite damping capacity. Under tension-compression cyclic loadin g, the martensite damping decreases as the number of cycles increases, and it tends to stabilize with further cycling.