A unified approach to quantify the role of friction in beam-type specimens for the measurement of mode II delamination resistance of fibre-reinforced polymers

This paper presents an approach that captures the effect of frictional force in beam-type specimens that are used for delamination tests in shear mode (mode II), including end-notched flexure (ENF), end-loaded-split (ELS), 4-point bend ENF (4ENF) and over-notched-flexure (ONF) tests. The approach is based on crack tip element analysis, and produces a single parameter that quantifies the role of the frictional force on the energy release rate for delamination. The parameter is a combination of the coefficient of friction of the contact surfaces and dimensions of specimens used in the tests. Accuracy of the parameter for quantifying the frictional force effect is evaluated by comparing the prediction with that based on finite element modeling. The comparison shows excellent agreement. Therefore, the study concludes that the parameter provides an accurate measure of the frictional force effect on the energy release rate for delamination in the beam-type specimens.