Potential improvement for elastocaloric performances of shape memory alloys through comparing with natural rubber

TL;DR

This paper compares the elastocaloric effects of natural rubber and shape memory alloys, proposing methods to enhance SMA performance by applying static pre-stress, inspired by improvements in natural rubber.

Contribution

It introduces a pre-stress approach to improve elastocaloric effects and fatigue life in SMAs, inspired by natural rubber's phase transformation mechanisms.

Findings

Pre-stress reduces large dynamic stress in SMAs.

Pre-strain improves elastocaloric effect and fatigue life in natural rubber.

Method enhances elastocaloric performance of SMAs through phase transformation control.

Abstract

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.