A note on thermomechanical coupling effects in the indentation of pseudoelastic shape memory alloys

TL;DR

This paper investigates how thermomechanical coupling effects, due to latent heat during phase transformation, influence the indentation response of shape memory alloys, especially at micro and nano scales, using a phenomenological model and finite-element simulations.

Contribution

It demonstrates the significance of thermomechanical couplings in indentation-induced martensitic transformation in SMAs through modeling and simulations.

Findings

Thermomechanical effects are significant at certain spatial and temporal scales.

Maximal thermal effects during adiabatic indentation are quantified.

Couplings influence the indentation response notably at micro/nano scales.

Abstract

While macroscopic experiments on polycrystalline shape memory alloys (SMAs) reveal significant thermomechanical coupling effects arising from the latent heat of transformation, the relevance of thermomechanical couplings in indentation tests remains ambiguous. This ambiguity is further emphasized by the rate effects observed in a number of micro/nano-indentation experiments, thus highlighting the need for a more careful investigation of the thermomechanical interactions at such small scales. With this in mind, the present study aims to demonstrate the role of thermomechanical couplings in indentation-induced martensitic transformation in SMAs. To this end, a simple phenomenological model of pseudoelasticity is employed and finite-element simulations are performed to address two key questions. (1) At which spatial and temporal scales do the thermomechanical couplings arising from the latent heat become effective? (2) To what extent do these couplings influence the indentation response? In connection with the latter, our analysis quantifies the maximal thermal effects that emerge during adiabatic indentation and compares them with those of isothermal indentation.