Cohesive Zone Modeling of Propellant and Insulation Interface Debonding

The reliability of the bonding of propellant to insulation is a key part of the analysis of rocket motor structural integrity. In this study, the debonding of the propellant/insulation interface was investigated by combining experiment and simulation. The improved exponential cohesive zone model and the bilinear cohesive zone model were used to predict the fracture properties of the adhesive interface. Double cantilever sandwich experiments and uniaxial tensile tests were performed to determine the corresponding model parameters. Furthermore, cohesive parameters were calibrated by applying an inverse analysis based on Hooke-Jeeves optimization algorithm. Good agreement was observed between the numerical simulation of double cantilever sandwich beam tests and the experimental curves. These results demonstrate that cohesive zone models can simulate the crack initiation and propagation of propellant/insulator interface in mode I. The bilinear law was shown to be more suitable for simulating fracture of the propellant/insulation interface in a strict sense than the exponential law. The numerical load-displacement curve was found to be sensitive to all cohesive parameters.