基于CW-THz的防热瓦结构缺陷深度检测校正方法

Method of Depth Detection and Correction of Thermal Proof Tile Structural Defects Based on CW-THz

太赫兹探测成像技术在航空航天无损检测领域具有重要应用前景,采用无损检测方法对热防护材料进行相关检测,对保证材料质量以及提高其使用可靠性等都具有重要意义。因调频连续太赫兹采集信号受系统工作带宽的限制导致测试精度低,为提高其测量精度,本文引入不同的离散频谱校正与细化方法进行比较分析。以热防护结构的陶瓷防热瓦为研究对象,对防热瓦中不同深度的孔洞缺陷进行检测,通过分析样件的太赫兹二维图像以及典型信号对比,获取缺陷的位置和大小信息,从信号处理的角度进行深度信息校正。结果表明,调频连续太赫兹检测系统可以清晰识别热防护结构中的孔洞缺陷,且离散频谱细化及校正处理算法能较准确的定位缺陷深度,其校正误差在1 mm范围内。

Terahertz detection imaging technology has an important application prospect in the field of aerospace nondestructive testing,the use of nondestructive testing methods to detect thermal protective materials is of great significance to ensure the quality of materials and improve their reliability.The frequency modulation continuous terahertz acquisition signal is limited by the operating bandwidth of the system,resulting in low test accuracy.In order to improve the measurement accuracy,this paper introduces different discrete spectrum correction and thinning methods to compare and analyze.Based on the thermal protection ceramic tiles,the hole defects of different depths in the tiles were detected.The position and size of the defects were obtained by analyzing the two-dimensional terahertz images of the samples and comparing the typical signals,and the depth information was corrected from the point of view of signal processing.The results show that the frequency-modulated continuous THZ detection system can clearly identify the hole defects in the thermal protection structure,and the discrete spectrum thinning and correction processing algorithm can accurately locate the defect depth,and the correction error is within Imm.