Interfacial fracture criteria based on the nominal deformation energy of interface

• Cracking and debonding criteria of interface can be developed in the same way.
• The theory agrees well with corresponding experimental results.
• The theory can be degraded into well known empirical criteria for some bonded materials.
• To characterize the interfacial toughness behaviors, K1C and K2C are enough.
• To characterize the interfacial strength behaviors, σC and τC are enough.

A nominal strain energy density of interface has been introduced to represent the deformation state of interface. By assuming that there are deformation capacities for volume and distortional deformation energy of interface, the interfacial fracture criterion for an interface crack and the interfacial debonding criterion for a perfect bonded interface have been developed. Both these two interfacial fracture criteria agree well with experimental results. It is found that two interfacial toughness properties, K1C and K2C, are enough to characterize the fracture behaviors of an interface, and two interfacial strength properties, σC and τC, are enough to characterize the strength behaviors of an interface. The theory also indicated that the discontinuous stress components parallel to the interface may also affect debonding.