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近几年兴起的激光超声检测技术,在对微裂纹检测方面以其非接触、宽频带等优点受到广泛关注,取得一定进展,但是目前并没有统一的理论解释裂纹和超声信号作用机理。从能量角度分析研究发现,裂纹的存在会消耗超声波的能量,造成能量衰减,同时理论计算与实际值之间存在比例系数。通过能量衰减计算公式,设计并进行实验,利用波形幅值的平方近似代替波形能量,通过两者对比,对比例系数进行拟合,然后计算出未知裂纹深度的比例系数,并由此反推预判未知深度裂纹对应的能量衰减值,实现对裂纹定量检测的目的。
In recent years, the rise of laser ultrasonic testing technology has made great progress in the detection of micro-cracks due to its advantages of non-contact and wide frequency band, and some progress has been made. However, there is no unified theory to explain the mechanism of crack and ultrasonic signal. From the energy point of view, the study found that the existence of cracks will consume ultrasonic energy, resulting in energy attenuation, while the theoretical calculation and the actual value of the ratio between the coefficient. Through the energy decay formula, the experiment is designed and carried out. The square of the amplitude of the waveform is used instead of the energy of the waveform. By comparing the two, the proportional coefficient is fitted, and then the proportion coefficient of the unknown crack depth is calculated. Judgment of the unknown energy value of the depth of the crack attenuation, to achieve the purpose of quantitative detection of cracks.