Mixed mode fracture in epicycloid specimens III. Dislocations

Complex stress potentials are derived to obtain an analytical solution for the stresses in epicycloidal specimens which contain a dislocation. The sol ution is used to obtain an analytical expression for the stress intensity f actors of cusp-like cracks in such specimens which can be considered as a g eneralization of the well established concept of Griffith cracks. It is sho wn that by suitable positioning of the dislocation, both positive and negat ive mode I stress intensity factors will result. This illustrates the poten tial of epicycloid specimens for determination of fracture properties under compressive loading where frictional contact of the crack surfaces is a pr iori avoided. (C) 1999 Elsevier Science Ltd. All rights reserved.