Stress intensity formulas for three-dimensional cracks in the vicinity of an interface

In this study, stress intensity formulas are considered in terms of the square root of area parameter to evaluate arbitrary shaped defects or cracks in the vicinity of an interface. Here "area" is the projected area of the defect or crack. Stress intensity factors for an elliptical crack parallel to a birnaterial interface are considered with varying the distance, aspect ratio of the crack, and combinations of material's elastic constants. Also, stress intensity factors of an interface crack and a crack in a functionally graded material are investigated. Then, it is found that the maximum stress intensity factors normalized by the square root of area are always insensitive to the crack aspect ratio. They are given in a form of formulas useful for engineering applications.