Energy-based analyses of delamination development in fibre-reinforced polymers under 3-point bending

A study was conducted to investigate possibility of predicting delamination development in fibre-reinforced polymer specimens that have single off-axis insert layer and are subjected to 3-point bending. Experimental results showed that the delamination development was at a very fast rate, which occurred at nearly constant deflection. Using high-speed photography, energy consumed for specimen vibration that was caused by the rapid delamination growth, was quantified and found to be a small fraction of the total energy loss incurred for the delamination development. Critical strain energy release rate for delamination (Gc) was determined after removing this part of energy loss from the total energy loss, and was used in two analytical approaches to predict the delamination size development, based on energy release rate (G) and change of total energy, respectively. Results show that the two approaches provide upper and lower bounds of delamination size observed in the 3-point bending tests.