Early effects of temperature-dependent yield stress in a transient analysis of fracture

Summary A semi-infinite crack grows due to stress wave diffraction in a thermoelastic solid. A rudimentary inelastic zone at the crack edge acts both as a heat flux site and as a crack-blunting mechanism. The first-step transient analysis treats constant crack/zone extension speeds and elastic properties. The yield stress, however, is allowed to vary with temperature.A relation involving the a priori unknown heat flux in the zone and an expression for the temperature response at the zone edge are found in the period right after fracture/zone initiation.These indicate that the applied (incident wave) stress must exceed the value necessary for zone formation predicted by a non-thermal analysis. The zone edge temperature increases rapidly at first, but then begins to level off in the same range of values noted in steady-state analyses at the time limit of the model validity. This temperature rise varies inversely with zone growth rate. A temperature-dependent yield stress definitely enhances the temperature rise, although the rise histories for this and a constant yield stress do not differ markedly in form.