Dynamic mode I perturbation solution for a moving crack unsteadily

method for the resolution of all stress components from the first invariant J, measured by thermoelastic stress analyzer is described. This method may be used to determine, not only surface stress, but also internal stress and stress on the underside. The method is based on the following procedure : (1) Pick an arbitrary domain 8, within the structure, for which the stresses are required. (2) Measure J, on the surface of a. (3) Determine the optimum traction along the boundary r, which is a part of R, by the least squares method such that the difference between the measured J, and the calculated J, is at a minimum. Either FEM or BEM may be used for this calculation. Examples of stress resolution for a two-dimensional stress concentration problem and a threedimensional stress concentration problem are shown. The accuracy of the stress resolution is discussed. 0 1997 Elsevier Science Ltd