A Spring Foundation Model for Mode I Failure of Laminated Composites Based on an Energy Criterion

Abstract

A mechanical model which can predict mode I delamination failure of laminated composites has been developed. A beam on a nonlinear spring foundation was used to model experimental results obtained from DCB type fracture specimens. The entire thickness of the beam specimen was used as a spring length, and a nonuniform strain distribution throughout the spring length was utilized, based on the 2-D asymptotic solution of the stress field near a crack tip. The failure condition of the spring foundation is based on an energy criterion. Mode I fracture tests were performed to verify the current model using two types of laminated composite DCB specimens. The current model reproduced the experimental results of pulling force versus crack opening displacement curves very closely for a wide range of resin layer thickness of the specimens. The current model has a potential capability of being extended to solve 2-D crack problems, where the evolution of an arbitrary shape of 2-D crack geometry will be predicted as a part of the solution of the current model.