A Note on Thermomechanical Coupling Effects in the Indentation of Pseudoelastic Shape Memory Alloys

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.