Investigation of the residual stress effect on thermoelastic behaviour of a rolled AA2024

Abstract

The Thermoelastic Stress Analysis (TSA) is a contactless technique based on the thermoelastic effect that consists of the generation of small temperature variations caused by the volume variations induced by stresses applied in the linearelastic range. Recent works demonstrated the capability of the TSA for the characterization of materials behaviour in presence of residual stresses. The use of a general TSA analytical expression allows the researchers to find a relationship between the amplitude of the thermal signal varying at the same frequency as the applied load and the characteristics of the residual stress tensor in terms of principal stresses and their direction. The just said relationship, under certain conditions, can be also affected by the uncertainty in the knowledge of the thermo-physical properties of the material which can enhance or blur the presence of residual stresses. In this work, the effect of the main variables, such as the material properties and the presence of residual stress on the TSA were investigated by applying a sensitivity analysis to the analytical general model. The analytical results were then verified and compared with TSA experimental measurements performed on AA2024 samples affected by biaxial residual stresses and the residual stresses measured with a standard test method.