Numerical simulation of cook-off of solid rocket motor

Investigating the cook-off behavior of solid rocket motor filled with high energy propellant is significant for its safety application. A coupled thermal-mechanical model is developed for the thermal reaction process of propellant in solid rocket motor. A one-step chemical kinematic reaction model is employed for the cook-off of propellant while thermal elastic material model is used for the solid rocket motor constituents. The temperature profile, structure deformation, strain and stress distributions are obtained. The influences of heating rates and geometry size on the explosion time and ignition region were discussed. A pressure dependent deflagration model is used to predict the mechanical response of solid rocket motor after the ignition of propellant. The mechanical behaviors of the solid rocket motor constituents are represented by a plastic kinematic model while a JWL expression is used for the equation of state for gases of explosion products. The mechanical response of solid rocket motor is calculated using the nonlinear finite element method. The pressure of deflagration product of propellant in solid rocket motor and the expanding velocity of the case during cook-off are obtained. The calculated results indicate that heating rate has a great influence on cook- off behaviors. That ignition region lying in the center of propellant would cause more violent explosion response of solid rocket motor.