Understanding the failure of epoxy resin U-notched samples using cohesive models

Abstract The critical distances theory for predicting failure loads of notched solid polymers requires assuming very high values of the characteristic stress. These values have to be much higher than the nominal tensile strength without a reasonable explanation. The use of cohesive models for linear elastic materials also requires very high cohesive stress values so that the results of the models are closer to the experimental ones. This paper has analysed the failure of a batch of three-point bending specimens with different notch radii made of epoxy resin. Numerical simulations based on a cohesive model considering the elastic-plastic material have been carried out. The results are compared with previous results obtained from experimental three-point bending tests. Additionally, the effect of triaxiality on the cohesive stress values required to get good predictions of the experimental failure loads has been also analysed.