Improvement of accuracy of inverse analysis for stress separation in thermoelastic stress analysis

This paper considers determination of individual stress components from the sum of the principal stresses obtained experimentally by the thermoelastic stress analysis. The stress separation problem is divided into two parts: (I) an inverse problem to estimate the unknown boundary values from the knowledge of the sum of the principal stresses inside the analysis region, and (2) a forward problem to compute the stress components inside the analysis region based on the estimated boundary values. These two problems can be formulated and solved by the BEM. As the inverse problem is often ill-posed, two techniques are adopted so as to attain an accurate result. One is pre-processing of experimental data, that is filtering based on the compatibility equation. The other is regularization of the inverse problem by Tikhonov's method with Hansen's L-curve method. The effectiveness of developed method is verified by applying it to an experimental data. The effect of configuration of the analysis region on the accuracy of stress separation is also discussed.