Progressive delamination and fiber bridging modeling in double cantilever beam composite specimens

摘要

The dependence of R-curves on the geometry of double cantilever beam (DCB) specimens was investigated for a unidirectional epoxy-carbon composite. Extended bridging was observed during the crack propagation and R-curves for three different thicknesses were obtained. A simple numerical procedure was proposed for the crack propagation modeling by taking into account linear and nonlinear bridging laws. The results were compared with different approximate formulae for the energy release rate calculations and an appropriate formula was found. By measuring the deflection in two points of a DCB specimen and the applied load as a function of crack propagation, an exact bridging law for the composite investigated was found. These data and the numerical procedure proposed allowed us to predict the R-curve for any thickness of a DCB specimen.