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

In inspecting steel-rubber multi-layered structure, shielding of steel layer and intense attenuation of rubber layer result in ultrasonic echo from the interfaces 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 and Lamb wave testing. In the double modetesting transverse wave and Lamb wave will be produced in steel 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 has been developed for the academe. Diagnosing images of the three interfaces and thicknessimages of insulation layer and under layer are obtained.