抄録
The critical Weibull stresses for brittle fracture of cracked specimens tested under different loading mode, that is mode I and mixed mode of I and II, estimated with an original Beremin model based on a linear fracture mechanics does not present the unique value. Local fracture driving force to control brittle fracture of a micro-crack in the material under large-scale yielding and combined loading conditions is analyzed based on nonlinear elastic-plastic energy release rate, Local-J of a unit cell containing a penny-shaped crack. Local-J is enlarged due to decrease in normal stress subjected to the horizontal direction with respect to a crack surface under the same normal stress, whereas such stress did not influence the linear elastic energy release rate. Also, the Local-J is significantly enlarged by shear stress acting on the crack plane. These results implied that the local fracture driving force Local-J should be taken into account for estimating the combined loading effect on brittle fracture resistance under large scale yielding condition.
