Abstract: Based on the characteristics of the bonding structure of metal shell/ceramic matrix composite material for solid rocket engine nozzle, the applicability of liquid coupled ultrasonic reflection method, ultrasonic penetration method, and ultrasonic phase method for detecting bonding quality was analyzed, and it was found that they are all difficult to detect. A method of air-coupled Lamb waves at one side was proposed, and the proposed testing method was used to test the bonding specimens of 304L stainless steel and C_f/SiC composite materials containing artificial debonding defects. The detection results and analysis indicate that the proposed method does not use liquid coupling agents, but directly uses air as the coupling agent, and the probe was arranged on the outside of the product, which was suitable for the detection of solid rocket motor nozzles after loading; the method of using soundproof panel was proposed to solve the problem of difficult distinction between Lamb waves and straight through waves, successfully achieving the separation of Lamb wave detection signals at the debonding point; all artificial debonding defects were detected in the solid rocket motor nozzle specimens, with a detection sensitivity of 5 mm×2.5 mm. The dimensional errors in the length and width directions of the defects were not greater than 2 mm, and the error in the defect area was not greater than 15%, achieving ultrasonic testing of the bonding quality of the engine casing/composite material.

Key words: engine, composite, ultrasonic, air-coupled, lamb wave, debonding, soundproof panel