基于太赫兹时域光谱技术的陶瓷基复合材料缺陷检测成像研究

Research on Defect Detection Imaging of Ceramic Matrix Composites Based on Terahertz Time-domain Spectroscopy Technology

陶瓷基复合材料(Ceramic matrix composites,CMC)具有密度低和耐高温等一系列优点,广泛应用于飞机机翼前缘与先进燃气涡轮发动机等部件。由于在其生产过程中存在着制作工艺多样和制作步骤繁复等因素影响,材料内部不可避免地会存留缺陷,这对材料质量稳定性以及可靠性都造成了不可忽视的影响。针对其内部缺陷检测的迫切需求,基于太赫兹时域光谱(Terahertz time-domain spectroscopy,THz-TDS)技术具有信息量丰富、时间分辨率高的优势,提出一种用于CMC内部缺陷无损检测的太赫兹检测方法。首先,采用反射式THz-TDS系统,对预制的CMC试样进行了非接触式无损检测,获得样品逐点扫描检测信号。然后,针对其高频信号在高阶滤波后常出现的明显相位延迟现象,提出一种零相位滤波方法,消除相位延迟并精确提取出峰值、相位与渡越时间等信息。在此基础上,采用多特征加权融合成像方法绘制材料缺陷的二维表面成像结果,并重构与其对应的缺陷三维形貌图,直观展示出了缺陷形貌位置信息,最终实现了CMC试样的缺陷定位与尺寸定量评估。

Ceramic matrix composites(CMC)have a series of advantages such as low density and high temperature resistance,and are widely used in components such as the leading edge of aircraft wings and advanced gas turbine engines.Due to factors such as diversified manufacturing processes and complicated manufacturing steps in the production process,defects inevitably remain in the material,which has a non-negligible impact on the stability and reliability of the material.In response to the urgent need for internal defect detection,based on the advantages of rich information and high time resolution of terahertz time-domain spectroscopy(THz-TDS)technology,a terahertz detection method for non-destructive detection of internal defects of CMC is proposed.First,the reflective THz-TDS system is used to perform non-contact non-destructive testing on the prefabricated CMC sample,and point-by-point scanning detection signals are obtained in the sample.Then,in view of the obvious phase delay phenomenon that often occurs in the high-frequency signal after high-order filtering,a zero-phase filtering method is proposed,which eliminates the phase delay and accurately extracts information such as peak value,phase and time-of-flight.On this basis,the multi-feature weighted fusion imaging method is used to draw the two-dimensional surface imaging results of the material defect,and the corresponding three-dimensional defect topography is reconstructed,and the defect topography position information is visually displayed,and the location and quantitative evaluation of the defects in the CMC sample are achieved.