TRANSIENT THERMAL FRACTURE OF AN INTERFACE CRACK IN THE PRESENCE OF ASURFACE CRACK

The effect of a surface crack on the strain energy release rate G(i) f or an interface crack between two dissimilar materials subjected to a transient thermal load is studied It is shown that the presence of a s urface crack is detrimental to the interface crack. Consideration of t he surface crack shows that the longest crack does not experience the largest G(s). A top layer with the smallest modulus of elasticity and a thermal expansion coefficient approximately 10 percent smaller than that of the bottom layer results in the smallest maximum strain energy release rates for both cracks.