TIME CALCULATION FOR THE AFTER-CURE COOLING PROCESS OF THE CAST MODIFIED DOUBLE-BASE PROPELLANT IN A LARGE ROCKET MOTOR

An unsteady heat conduction model is proposed to calculate the temperature distribution of the case-bonded rocket motors and the time required for the cooling process based on the experimentally determined thermal and mechanical parameters of a cast modified double base propellant (CMDB) and its glass steel shell. The resultant value of the time is then used to derive the corresponding stress relaxation modulus, which is compared with the modulus data obtained from uniaxial tensile stress relaxation experiments to see if the internal stress has been thoroughly relaxed within this period of time.