A New Measuring Method of Residual Stresses with the Aid of Finite Element Method and Reliability of Estimated Values

Abstract

In estimation of residual stresses, the existing methods are mainly based on the idea that variation of strains on the surface of the object is measured by sectioning continuously until any variation of the measured strains corresponding to the residual stresses is not observed. In this kind of methods, some definite mathematical relation between the variation of stresses and the released surface forces is required. This kind of relation was obtained only for the cases where the geometry and the boundary condition of the object and the pattern of residual stress distribution are simple. This restriction is removed when numerical methods, such as the finite element method, etc. are adopted. In this paper, a general theory is developed based on the finite element method. With this method, three dimensional residual stresses can be measured. Furthermore, reliability of estimated values of residual stresses by this method is mathematically studied when errors are contained in the measured strains.