Thermo-mechanically coupled phase-field fracture model considering elastocaloric effect of shape memory alloy

TL;DR

This paper introduces a thermo-mechanically coupled phase-field fracture model for shape memory alloys that incorporates elastocaloric effects, enabling simulation of fracture processes influenced by non-isothermal martensitic transformations.

Contribution

A novel phase-field model that integrates elastocaloric effects and thermal-mechanical coupling to simulate fracture behavior in shape memory alloys.

Findings

Martensite nucleates at stress concentrations and spreads at 45 degrees.

Elastocaloric effect-induced thermal expansion enhances load capacity.

Large phase transition kinetics and orientation angles increase eCE effects but reduce deformation capacity.

Abstract

Modelling fracture behavior of the shape memory alloy (SMA) that interacts with martensitic transformation and the associated elastocaloric effect (eCE) still remains challenging. Herein, a thermo-mechanically coupled phase-filed fracture model considering elastocaloric effect of SMA is proposed to simulate the cracking process coupled with the non-isothermal martensitic transformation and the associated eCE. In the phase-field model, both the thermal strain induced by eCE and the eigen strain induced by the phase transition are considered. An empirical degradation function is adopted to describe the thermal conductivity decreasing with the fracture order parameter. The model is validated with the finite element method and tensile fracture properties of Mn-Cu SMA are simulated. It is found that the martensite variant nucleates at the stress concentration where the crack initiates, and commonly spreads with an angle of 45 degree. The thermal expansion strain caused by the eCE could strengthen the critical load capacity. A large kinetic parameter for phase transition and the large orientation angle could enhance the strength and temperature change of eCE while the deformation capacity is reduced. The phase-field model demonstrates its ability in the thermal-mechanically coupled toughening of SMA. It also provides a possible fracture-resistance strategy by the utilization of eCE for elastocaloric devices.