Effects of loading rate on fracture behavior and mechanism of thermoset epoxy resin

Effects of loading rate on fracture behavior and mechanism of thermoset epoxy resin with polyamine hardener have been studied at various loading rates (10(-1)-10(3) mm/min). The displacement to fracture continuously decreased with increasing loading rate, and became stable at high loading rates. The maximum load, critical stress intensity factor (K-IQ), and critical strain energy release rate (G(IQ)) were high and stable at low loading rates, and became low and stable at high loading rates with the transition of loading rate at approximately 10 mm/min. The formation of shear lips, stretched zone, crazes, and crack blunting, i.e. localized plastic deformation processes, were dominating mechanisms and resulted in the plane stress-dominated condition for specimens tested at low loading rates, while brittle fracture and the condition of plane strain were dominating mechanisms for specimens tested at loading rate of 10 mm/min or higher. (c) 2005 Elsevier Ltd. All rights reserved.