Research on weak bonding defect detection based on laser shock wave

In order to study the detection ability of the laser shock detection method for “weak bonding” defects, carbon fiber reinforced plastic (CFRP) bonding specimens with different pollution levels were prepared. Tensile shear test was performed on the specimens first, and laser shock wave generation system was used to perform laser shock on them. The impact detection results were observed and compared with the results of tensile shear test. The results show that, the tensile shear strength of the contaminated specimens decreases by about 55% ~ 78% compared with that of normal bonding, and the failure mainly occurs at the bonding interface, which conforms to the characteristics of “weak bonding”. When the pulse width of the laser is 30 ns, the spot diameter is 4 mm, and the laser energy is 3.68 J, the normally bonded specimen begins to spalling, while the 2.76 J and 1.84 J laser energy shock can cause damage to the contaminated specimen without damaging the normally bonded specimen. The damage size is related to the bonding strength of the specimen, and the location of the damage is also consistent with the fracture location of the interface in the tensile shear test. The results indicate that laser shock detection can effectively identify weak bonding defects. This result is helpful to the development of weak bonding detection technology.