变厚度复合材料结构超声反射法成像的缺陷识别与定量表征

Defects recognition and quantitative characterization of ultrasonic reflection imaging in variable thickness composite structure

针对复合材料零件中常见的变厚度层压板结构,提出了一种超声C扫描反射法自动化检测成像与缺陷识别方案。其基本原理是根据变厚度零件的厚度范围设置包含最大有效分析区间的闸门,分别采集“尾沿位置”、“首沿位置”、“峰值位置”和“尾沿波幅”信号进行成像,形成4幅C扫描图。通过分析缺陷识别的原理,总结归纳出变厚度零件中的分层、脱黏、夹杂、孔隙密集等4种典型缺陷的识别方案,从而解决了零件底波位置变动导致的不易获取缺陷分析区间的问题。对含有典型人工缺陷的试块进行C扫描反射法检测并对检测结果进行定量分析,结果表明:该自动化检测方案能够准确地识别变厚度零件中的缺陷,对缺陷尺寸的评判具有较高的可靠性。

This paper introduces an imaging and recognition method of pulse echo ultrasonic C-scan automatics technology to test variable thickness laminates structures which are extensively used in composite parts. The principle lies on the setting up threshold of effective analysis interval based on the thickest area of laminate to collect the “position of last edge”, “position of first edge”, “amplitude of any peak” and “amplitude of last edge” signals, and hence to form four pairs of C-scan images. By analyzing the theory of defect identification, the recognizing method of typical defects, such as delamination, disbonding, inclusion and porosity density is concluded. This technology can solve the problem of hard to acquire effective analysis interval caused by bottom wave shifting in pulse echo method. By using the method of pulse echo ultrasonic C-scan to detect the reference block with typical defects and by quantitatively analyzing detection results, the experimental results show that the defects in variable thickness parts can be well found by this method, and the judgment of defects size is reliable.