The effect on the mode Ⅰ stress intensity factor of plastic dissipation in heat at the crack tip under cyclic loading

摘要

Plastic dissipation at the crack tip under cyclic loading is responsible for the creation of an heterogeneous temperature field around the crack tip. A thermomechanical model is proposed in this paper for two problems: (ⅰ) an infinite plate with a semi-infinite through crack and (ⅱ) a centre cracked plate specimen, both under mode Ⅰ cyclic loading. The heat source is assumed to be located in the reverse cyclic plastic zone (RCPZ). The solution of the thermomechanical problem shows that the crack tip is under compression due to thermal stresses coming from the heterogeneous temperature field around the crack tip. The effect of this stress field on the stress intensity factor (its maximum and its range) is calculated. The heat flux within the RCPZ is the key parameter to quantify the effect of dissipation at the crack tip on the stress intensity factor.