Stress intensity factors for two parallel interface cracks between a nonhomogeneous bonding layer and two dissimilar orthotropic half-planes under tension

In composite materials, which are constructed of two dissimilar orthotropic half-planes bonded by a nonhomogeneous orthotropic layer, one interface crack is situated at the lower interface between the layer and the lower half-plane, and another crack is located at the interface between the upper half-plane and the bonding layer. The stress intensity factors are solved under uniform tension normal to the cracks. The material properties of the bonding layer vary continuously from the lower half-plane to the upper half-plane. The stress intensity factors are calculated numerically for perpendicularly bonded unidirectional glass fiber reinforced epoxy laminae.