Constitutive model and activation recovery performance of Fe-SMA: Experimental and theoretical study

Abstract

In this study, the static tensile properties, activation recovery properties, and post-activation static tensile properties of the China-made iron-based shape memory alloys (Fe-SMA) were experimentally studied and theoretically analyzed. The material parameters of the Ramberg-Osgood curve are modified based on the static tensile tests of Fe-SMA plates, leading to the proposal of a static tensile constitutive model suitable for Fe-SMA. The applicability analysis of the theoretical model indicates that the calculated curve achieves an accuracy of R2 ≥ 0.9. Subsequent activation tests revealed a locally optimal combination of pre-strain and activation temperature, which is concluded to be associated with the martensite content. Hot-rolled Fe-SMA plates demonstrate local maximum utilization when subjected to a 4% pre-strain and an activation temperature of 300 °C, resulting in a recovery stress of 314 MPa. Moreover, it has been determined that the two activation modes, namely single heating and multiple-cyclic heating, do not significantly impact the final recovery stress of hot-rolled Fe-SMA plates. Therefore, the multiple-cyclic activation of Fe-SMA can be utilized to compensate for prestress loss in practical applications. Furthermore, a comprehensive constitutive model for Fe-SMA is proposed based on the results of the post-activation static tensile tests. This model provides an accurate description of the static-tensile stress-strain relationship of Fe-SMA during pre-straining and after activation. This study focuses on investigating the constitutive relationship and activation recovery performance of Fe-SMA, providing an experimental basis, data support, and theoretical analysis for the practical application and further analysis of Fe-SMA in structural reinforcements.