In order to study the structure stability of the solid rocket motor grain with a crack with different storage time

the theory of viscoelastic fracture mechanics and finite element method were adopted to calculate the J integral of the crack when the solid rocket motor was under the ejection load and the ignition load.The singular crack elements were employed when the J integral of the crack was calculated.The results of J integral of cracks with various shapes and in different storage time were discussed.The results show that the J integral of the crack decreases with storage time and crack propagation is not likely to happen when the motor is under the ejection load.However

when the motor is under the ignition load

the J integral of the crack increases with storage time and the crack is more instable and is more likely to propagate.