Evaluation of the effect of fiber bridging on mode I quasi-static testing

The purpose of this investigation is to evaluate the contribution of fiber bridging to the energy release rate of a fracture resistance curve. Fiber bridging occurs when testing beam-type specimens consisting of unidirectional plies in a laminate. Unidirectional double cantilever beam specimens composed of the carbon fiber reinforced polymer prepreg AS4/8552 were tested using standard methods. In addition, a cohesive zone model was developed and used to carry out finite element analyses on the tested specimens. It was employed to calculate the contribution of fiber bridging to the R$$ R $$-curve which was determined from the tests. Fiber bridging in beam specimens increases the apparent fracture toughness of a composite laminate. A method has been proposed for evaluating its contribution to the energy release rate. In that way, an R$$ R $$-curve may be determined for which the effect of fiber bridging is eliminated.