Interlaminar Fracture Toughness of GFRP Influenced by Fiber Surface Treatment

Abstract

The interlaminar fracture behavior of unidirectionally glass fiber reinforced composites with fiber surface treatments have been investigated in Mode I, Mode II and for a fixed mixed Mode 1/11 ratio. With respect to the loading conditions at the crack tip the double cantilever beam (DCB), the end notched flexure (ENF) and the mixed mode flexure (MMF) specimens were used in order to obtain Mode I, Mode II and mixed Mode I/II critical energy release rates. The data obtained from these tests have been analyzed by using analytical and finite element approaches. The present investigation is focused on the influence of the glass fiber surface treatment on the interlaminar fracture toughness. Glass fibers with two different fiber surface treatments have been investigated. For the DCB test the data reduction from the experiments have been carried out by using six different approaches: the area method. the Berry method, the modified beam analysis, the compliance method and the geometric linear and non-linear finite element analysis. The geometric non-linear finite element analysis of the DCB test was performed firstly. For the ENF test contact and friction along the crack surfaces have been taken into account.