超声A扫描信号建模及其缺陷识别方法研究

针对超声检测中A扫描信号依靠经验评定结构缺陷、识别缺陷类型困难等问题,提出一种A扫描信号建模方法,计算出缺陷A扫描信号。该方法基于超声检测系统建立A扫描信号数学模型,应用多元高斯声束法计算模型中缺陷表面超声波传播质点速度,运用基尔霍夫近似理论描述模型中缺陷散射振幅,从而获得缺陷超声A扫描信号。应用CSII-1/20标准试块平底孔(缺陷)超声A扫描表明:该方法计算获得试块平底孔5#(缺陷)A扫描信号与试验测量结果在缺陷位置和幅度基本吻合,是识别结构孔洞类缺陷的一种有效方法。

Ultrasonic A-scan signal modeling for structure defect recognition

A-scan signal of ultrasonic testing was always applied to evaluate structure defect. It was difficult to recognize structure defect type for the A-scan signal was directly evaluated on the basis of experience. Therefore this paper presented an approach of A-scan modeling for structure defect recognition. In this approach, an A-scan frequency-domain model was firstly developed, the multi-Gaussian beam model was given to calculate ultrasonic wave particle velocity of structure defect surface, and the Kirehhoff approximation theory was applied to describe structure defect scattering. Ultrasonic A-scan signal of structure defect was finally calculated. The results of ultrasonic testing of a fiat bottom hole in CSⅡ-1/20 standard test block showed that the waveform and amplitude of calculated A-scan signal were in good agreement with the experimental measurements. So, the approach can be effective to recognize a fiat bottom hole in structure.