DUCTILE FRACTURE BY THE GROWTH AND COALESCENCE OF MICROVOIDS OF NONUNIFORM SIZE AND SPACING

A two-dimensional plane strain model of void growth and coalescence in a rigid/plastic solid, containing void sizes and spacings which can be highly non-uniform, is developed to investigate the effects of non-uniform distributions of void-nucleating particles on the ductility of a metal. The theoretical void-growth strains to ductile fracture for a wide variation in void diameters and spacings show that, for a given volume fraction of voids, the minimum ductile-fracture strain occurs when the voids are of uniform size and spacing. For the same volume fraction of voids, greatly increased ductility is likely to be achieved when the void sizes and spacings are highly non-uniform and the sub-cell volume fractions are also non-uniform.