Surface monitoring technique for fatigue effect of shape memory alloys(SMAs)

There have been very few research results available for high cycle fatigue properties of SMAs. In many of the devices designed to exploit the effect of fatigue loadings, the specimen is subjected to only several thousand thermal or loading cycles. Therefore, the stability of the alloy under applied loading with high cycle fatigue becomes an important issue. Moreover, there has not been any fatigue testing in compression for SMAs. The behavior of SMAs under tension and compression may be different, which is very important for many special applications of SMAs. The present study focus on the high cycle fatigue of SMAs under compression. A new surface monitoring technique for micro-deformation and micro-strain analysis, called IIMT, is introduced. IIMT is used for monitoring the performance of SMAs under high cycle stress loading in compression. The stress-strain curves and shape memory strain output at various loading cycles were obtained, which provide valuable information for design and applications of SMAs.