Investigation on the reverse opening process of the soft insulator of double pulse solid rocket motor

The soft insulator working principle of double pulse solid rocket motor was presented in this paper. The reverse opening process of the soft insulator during the secondary firing was simulated via the method of explicit dynamics, then the further investigation on the opening process of the soft insulator was performed by the gas generator and the insulator experiment. The excellent agreement between the calculated result and the experiment proves the accuracy of the models and method. The research shows that brittle fracture criterion could accurately predict the failure position and the opening pressure of the soft insulator. The soft insulator ruptures firstly around the weakness under pressure shock loading, then the under cracked insulator gradually opens reverse afterwards, and the insulator fractures severely at the port finally. The research could be used for preliminary design of the soft insulator of the rocket motor.