Abstract
A crack terminating at an interface in fiber reinforced composites may advance by either penetrating through the interface or deflecting into the interface. To describe such a phenomenon, the energy release rate based on the interfacial mechanics is used in this work as the fracture criterion. The energy release rates for the crack deflecting into the interface and the crack penetrating the interface depend on the branch crack length Δa, which is arbitrarily small compared to the length of the main crack. When loading condition is a tensile load, the ratio of those energy release rates is independent of Δa. However, the ratio depends on Δa in case of thermal loading condition. A relation between the ratio and the stiffness ratio of the components (fiber and matrix) is investigated in cases of two loading conditions, and the debonding conditions are shown. The results can be used for determination of the range of interface toughness relative to fiber one, to ensure the cracks to be deflected into the interface for prevention of catastrophic fracture.
