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.
KEYWORDS: Titanium, Signal detection, Metals, Stress analysis, Aluminum, Signal analyzers, Temperature metrology, Infrared cameras, Numerical simulations, Detection theory
The Thermoelastic Stress Analysis (TSA) is a contactless technique able to determine the superficial stress of a component subjected to a dynamic load in a linear elastic field. In these conditions the thermoelastic effect shows the generation of small reversible temperature variations. In this work, a general equation was obtained for the evaluation of the thermoelastic signal. The proposed equation is valid under adiabatic and isentropic conditions, for generalized homogeneous and anisotropic materials in any load condition. By using the proposed generalized equation, TSA sensitivity to the variation of the physical and mechanical material characteristics and TSA sensitivity in the determination of residual stresses were studied. The case studies for performing numerical simulations were represented by AA6082 and Ti6Al4V non-ferrous metals. The results were then compared with the data obtained from experimental tests performed on AA 6082 samples.
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