Interfacial Fracture Toughness Between Hydroxyl-Terminated Polybutadiene Solid Rocket Propellant and Liner

The present work is aimed at studying the interfacial debonding behavior between the hydroxyl-terminated polybutadiene solid propellant and liner. The fracture mechanics method based on integral was used to evaluate the interface’s resistance against crack initiation and propagation, with the auxiliaries of the multisample test procedure and high-speed camera. The discrete fracture parameters at different interfacial-crack initiation moments and crack extension amounts, including the load, displacement, and fracture energy, were well fitted using the least-squares method and the second-order polynomial regression method. The crack blunting process was observed to fit the blunting line realistically. The 95% confidence intervals of fracture parameters were obtained by conducting the regression error analyses based on the -distribution to include the experimental uncertainties. The mean value of the crack initiation integral, , was obtained. The mean value of the apparent initiation fracture toughness, , was determined by combining the blunting line and -integral-based resistance curve. The regression result of was characterized by a narrower 95% confidence interval compared with the one of . Further, the interfacial-debonding mechanism and its influence on the overall failure were investigated.