Potential improvement for elastocaloric performances of shape memory   alloys through comparing with natural rubber
  The elastocaloric (eC) effects of natural rubber (NR) and shape memory alloys (SMAs) are compared and potential improvement for eC performances of SMAs is proposed. Both the plateau and hysteresis of stress-strain curve in NR and SMAs are observed. They are attributed to the similar phase transformation: strain-induced crystallization (SIC) in NR and martensitic transformation in SMAs. For NR, the drawback of large strain can be reduced by pre-strain. For SMAs, the stress change with strain is smaller in stress plateau regime. Thus, the drawback of large dynamic stress of SMAs is proposed to be reduced by a static pre-stress for working directly in this stress plateau regime. Choosing an appropriate pre-strain (pre-stress) and strain amplitude can make eC effect of NR working in the phase transformation (SIC) regime. This method can improve both the eC strength and fatigue life in NR. Due to the similar phase transformation (martensitic transformation) of SMAs to NR, this method is also proposed to improve the eC performances of SMAs. 
Zhongjian Xie, Gael Sebald, Daniel Guyomar
cond-mat.mtrl-sci