THE PROJECTED CONSERVATION THEORY OF THE J k VECTOR FOR MICROCRACK INTERFACE CRACK SHIELDING
界面微裂纹屏蔽J_k矢量投影守恒

It is proved from analytical treatments and computer experiments that the projected conservation relation of the J k vector, found for microcrack shielding problems in brittle homogeneous cases, is also valid for the shielding problems in bimaterial solids, although the characteristic oscillating stress singularity exists near the tip for an interface crack and the tension and shear modes are inherently coupled near the tip. As the relation is shown to be universal, it could be called as the projected conservation theory of the J k vector, which reveals the fact that there is a wastage when the remote J integral transmits across the microcrack zone in the relatively brittle material phase from infinity to the interafce crack tip. This wastage represents the well known sources for microcrack shielding effects reduction in the effective elastic moduli of the zone and the release of residual stresses arising from microcracking. It is also concluded that this wastage could be evaluated quantitatively by using the projected conservation theory mentioned above.