Grain defect character of solid rocket motor in ultrasonic test

The ultrasonic test probe with the frequency of 1MHz is optimal by analyzing viscoelastic property of material of solid rocket motor grain. The double-probe pulse echo method, combining the advantages of transmission technique and pulse reflection method, is used to optimize the ultrasonic echo signal amplitude in case of strong attenuation of energy when ultrasonic signal transmitting in solid rocket motor grain. The linear and quantitative nondestructive test of the grain defect is realized by using time-frequency domain character of the ultrasonic defect signal.