A SPECIMEN FOR DETERMINING FRACTURE PROPERTIES UNDER COMBINED MODES, I, II, AND III CRACK-TIP CONDITIONS

An axisymmetric, bar-type specimen, which contains conical, 'crack-like', external flaws, is described. The specimen can be used to obtain mixed-mode (I, II, and III) fracture data. These 'crack-like' flaws can be created in metallic and non-metallic materials by incorporating metal or ceramic shims in moulds used to cast the components. Mode I and mode II crack tip conditions are created in the specimen by subjecting it to an axial load, while mode III crack tip conditions are produced by applying a torsional load. Finite element analyses are performed and results are presented which enable the K(I), K(II), and K(III) values to be determined from the axial load, the torque, the bar diameter, the crack length, and the crack inclination.