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

The study addresses a modeling challenge: how cracks form in shape memory alloys when martensitic transformation and the elastocaloric effect (eCE) are both active. The authors propose a thermo-mechanically coupled phase-field fracture model that treats the process as non-isothermal. In the model, thermal strain from eCE and eigen strain from the phase transition are both included, and thermal conductivity is reduced as cracking progresses. They validate the approach using finite element method comparisons and simulate tensile fracture properties for Mn-Cu SMA. The simulations indicate that martensite variants nucleate near the crack initiation stress concentration and spread at about a 45° angle. The results suggest that thermal expansion strain from eCE can increase the critical load capacity, and that phase-transition kinetics and orientation angle influence both the strength/temperature change of eCE and the deformation capacity. The authors frame this as a possible fracture-resistance strategy for elastocaloric devices.