Research of Double Mode Ultrasonic Testing in Multi-layered Adhesive Structure of the Solid Rocket Motor

In inspecting steel-rubber multi-layered structure, shieldi ng of steel layer and intense attenuation of rubber layer result in ultrasonic echo from the int erfaces of the deep layers being very weak. In order to overcome the difficulty, the double mode testing method is put forward. This method synthesizes the characteristics of transverse wave an d Lamb wave testing. In the double modetesting transverse wave and Lamb wave will be produced in st eel layer at the same time. The researches in theory and experiment have proved that the method is feasible. According to the double mode testing principle, a C-scan inspection system ha s been developed for the academe. Diagnosing images of the three interfaces and thickness- images of insulation layer and under layer are obtained.