Evaluation of grid data to determine displacements and strains

Abstract

This paper deals with a new method to evaluate distorted grids. Instead of evaluating point-by-point the new method consists of shifting an image of a distorted grid over another image of the undistorted grid to obtain displacement components, or shifting an image of a distorted grid over another image of the same distorted grid to obtain the derivative of the displacement components. Whole field information is available by connecting grid line intersections.Displacements and their spacial derivatives are given for a circular ring diametrically compressed, using both the Eulerian and the Lagrangian descriptions. The method has applications in plasticity and in elastic finite strain determinations.