The glass plate specimens with inclined cracks introduced by Vickers microhardness indentation were subjected to sustained bend stress in water. Subcritical crack growth behaviors were investigated under combined Modes I and II loading. The crack velocity dc/dt can be described as a function of coplanar energy release rate G. The experimental results show that the dc/dt which is initially high decreases and thereafter increases with G. The crack velocity data are found to be influenced by the residual stress and the presence of a lateral crack. Inclined cracks in the increasing region tend to show the crack velocity higher than would be expected from the Mode I results of β = 90 deg on the basis of G as the β between the loading axis and the crack plane decreases. The dc/dt-G curves in this region have a steeper portion at low velocities and thereafter tend to a shallower portion.

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