A two-dimensional hybrid experimental-numerical technique for elastic-plastic stress analysis

A two-dimensional hybrid experimental-numerical technique for elastic-plastic stress analysis is presented. This technique results from merging two relatively new technologies in engineering mechanics: boundary element methods and image processing. A syntactic pattern recognition scheme termed 'Displacement Pattern Matching' (DPM) determines displacement boundary conditions to be used in an elastic-plastic boundary element (EPBEM) code. The result is an automated stress analysis tool.; Displacement pattern matching is a process where displacements are measured by tracking an arbitrary array of 'black' spots on a 'white' specimen. The digitized images of the specimen are compared in a double exposure format to determine displacements. Displacement pattern matching is a full field technique, with spatial resolution on the order of.0001 inch.; Displacement pattern matching supplies the actual specimen displacement increments to the von Mises, isotropic work hardening, boundary element code. Given these displacements and free surface conditions, EPBEM is able to incrementally calculate the internal state of stress at selected locations. Results obtained for a variety of geometries and loading conditions compared well with ANSYS finite element and selected published experimental solutions and therefore are encouraging.