A swept frequency type ultrasonic inspection method is used for inspecting not only case liner separations, but also liner propellant separations of solid motors, with its successful application to the H-I upper stage motors also being discussed. This new method has been in development at the National Aerospace Lab (NAL) since 1968, and is based on using the one dimensional quarter wavelength resonance principle to determine the liner thickness under both free and fixed end face boundary condition, being considered to be the liner's line propellant separation boundary condition. Since the motor cases have curved (spherical/cylindrical) surfaces, several curved contact surface probes were developed. This method was subsequently applied to test successfully both the apogee and third stage motor of the H-I rocket during manufacturing and also at the launch site. This inspection has contributed to successful launching of the H-I rocket since the first launching in August 1987, and will be applied to the Solid Rocket Booster (SRB) of the H-II rocket.
Swept Frequency Type of Ultrasonic Inspection Method for Liner-Propellant Separations of Solid Motors
1991
58 pages
Report
No indication
English
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