Digital Image Correlation

During surface deformations measurements in objects, materials or structural element samples, which move in the space, recorded speckle images are transformed by these displacements. In Chapter One, an algorithm for speckle image relative geometrical transformations parameters determination is proposed on the basis of Fourier-Mellin transform. Usage of this algorithm will allow increasing reliability of deformation fields determination for constructional materials after appropriate correction of speckle-images, which are used during calculations. In Chapter Two, methods are presented to determine forming limit curves (FLCs) for sheets of advanced high strength steels (AHSS) using digital image correlation (DIC). FLC is a valuable tool for failure prediction in forming simulation at design stage and die try-out in press shops. Chapter Three presents a novel algorithm for recovering the trajectories of mechanism components from high speed video by means of multidimensional simplex optimisation and conformal templates. The focus of this chapter is on a simplex-based approach to digital image correlation (DIC) with arbitrarily shaped subsets that provides a number of advantages over the traditional gradient based approach with strictly square subsets. Finally, Chapter Four aims to develop a different technique that allows the obtention of the stress-strain evolution of materials while they are under axial loads.