Mode I and II fracture behavior of adhesively-bonded pultruded composite joints

The Mode I and II fracture behaviors of adhesively-bonded joints composed of pultruded glass fiber-reinforced polymer (GFRP) laminates were experimentally investigated using Double-Cantilever-Beam (DCB) and End-Loaded-Split (ELS) specimens. The large specimen dimensions on the full-scale level and asymmetric crack propagation in the laminates imposed deviations from the standardized specimens. For crack length measurement, in addition to visual observation, a video extensometer was used. Similar strain energy release rate values were obtained from all standardized methods as well as from 3D finite element models, with the exception of Simple Beam Theory. The applicability of existing standards for interpretation of the fracture data for the fracture mechanics joints used was proved.