Mixed mode fracture in epicycloid specimens. I—Thermal inclusions

The technique of complex potentials is used to derive an analytical solution for the stresses that develop in epieycloidal specimens subjected to hot spot loading. The solution gives stress intensity factors for eusp-fike cracks in such specimens which can be considered as a generalization of the traditional Griffith crack. It is shown that by suitable positioning of the hot spot the complete range of mode mixety, as well as negative mode I stress intensity factors, can be obtained. This illustrates the potential of epicycloid specimens for testing of bimaterial fracture properties as well as failure under compressive loading without frictional contact of crack surfaces. The paper concludes with a first experimental measurement of Kx in order to validate this new concept. © 1998 Elsevier Science Ltd