Cause Analysis on Low Pressure Cracking of a Solid Rocket Motor Case

The causes of low pressure cracking during the hydraulic test of a solid rocket motor case were analyzed by chemical composition analysis, mechanical property test and macro and micro fracture analysis. The results show that the cracking property of the motor case was ductile fracture under low stress. The main reason for the cracking was the existence of microcracks in the local area of the motor case outer surface.