基于频率-波数域分析方法的金属板损伤检测与评估

Ultrasonic guided wave testing is one of the most important methods of structural damage detection. However, it is difficult to interpret signal of the complex wave field considering the multi-modal and dispersion characteristics of ultrasonic guided waves. Moreover, traditional contact transducer array unit scale leading to the lower spatial resolution of its pickup guided wave signal which limited the application of the ultrasonic guided wave in the actual damage detection. Confronting with these challenges, this paper adopted the frequency wave-number field analysis method to study the local wave number damage imaging algorithm. We can use the dispersion characteristic, the wave-number is changed with the product of frequency and thickness, take the wave-number change in lesion location as the evaluation indicator of damage. Symbols of wave number indicate the reflected wave forming in the damage position and the depth of the amplitude of wave number may indicate the level of damage. On the other hand, amplitude of wave number may indicate the depth of damage. The research establishes the non-contact high resolution of spatial pickup platform in ultrasonic guided wave field based on the SLDV. This study images damage of different depth in metal aluminum plate using abundant measured data in wave field, and compares the experimental result with the result of numerical simulation to verify the effectiveness of the imaging algorithm. The theory and method in this study can be used to guide the engineering practice.