Analyses of delamination of notched laminated beams by three-point bend test based on the theory of large deflection.

Abstract

A fracture mechanics-based study is presented on delamination of notched laminated beams by a three-point bend test. The model crack is T-shaped ; namely it consists of an interface crack and a notch normal to the beam surface, and the delamination is identified with the extension of the interface crack. Based on the assumption that the specimen behaves like a beam with a reduced section of length of interface crack, the compliance of the specimen is derived by using theory of large deflection of beams, i.e., the problem is treated as that of elastica. The energy release rate and the condition for delamination are then obtained based on the Griffith's energy balance concept. It is found that the form of the delamination condition expressed in terms of the length of the interface crack and the deflection at the point of loading is equal to that derived from simple beam theory.