INVERSE ANALYSIS RELATED TO STRESS SEPARATION IN THERMOELASTIC STRESS-ANALYSIS

Thermoelastic stress analysis (TSA) is a technique for measuring stres ses through temperature changes induced by the thermoelastic effect of elastic bodies. Since the TSA can only provide the sum of the princip al stresses, stress separation is required to obtain individual stress components. This paper deals with stress separation of TSA data. The problem is divided into two: (1) an inverse problem to estimate the un known boundary values from the sum of the principal stresses inside th e body, and (2) a direct problem to derive the stress components insid e the body on the basis of the estimated boundary values. This two-ste p method can be applied to a wide range of practical problems if both the inverse and direct problems are solved by FEM or BEM. In this stud y, the problem is formulated by BEM. It is shown that careful treatmen t of the inverse problem is essential for attaining an accurate result of the stress separation. The combination of the truncated singular v alue decomposition and Hansen's L-curve method is found to be effectiv e for the purpose.