基于复Morlet小波相位的红外调制热像检测方法
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摘要
为了提高红外调制热像法对复合材料缺陷的检测能力,研究了利用基于复Morlet小波相位分析的红外热像序列处理方法。依据热激励调制频率和红外图像采样频率,自适应地选择小波变换尺度总数,然后利用复Morlet小波系数相位从原始热像序列重建相位图序列。对含有分层缺陷的玻璃纤维增强复合材料参考试件进行了调制热像检测实验,以信噪比为评价指标对该方法的实际处理效果进行了定量评定,并与傅里叶变换法进行了对比。结果表明:复Morlet小波相位法可以分离调制热像信号的低频和高频噪声,能稳定地提取试件不同深度的分层缺陷,对热激励调制频率的变化有良好宽容性,因此是调制热像法的有效数据处理方法。
In order to increase the detection capability of infrared modulated thermography for defects in composite materials, an infrared image sequence processing method using the complex Morlet wavelet phase analysis was studied. According to the modulation frequency of thermal excitation and the sampling frequency of infrared imaging, the total number of scales used in wavelet transform was selected adaptively, and then a phase image sequence was reconstructed from the raw thermal image sequence by using the complex Morlet wavelet coefficients. An experiment of modulated thermography was performed on a glass fiber reinforced plastic reference sample containing delamination defects, the application effects of the method were quantitatively evaluated and compared with the Fourier transform method by the signal-to-noise ratio. The results show that the complex Morlet wavelet phase method can separate the low frequency and high frequency noise from the thermal image signal, and extract the subsurface defects at different depth robustly; it keeps a good tolerance to the change of the modulation frequency; so it is an effective algorithm of the modulated thermography.
In order to increase the detection capability of infrared modulated thermography for defects in composite materials, an infrared image sequence processing method using the complex Morlet wavelet phase analysis was studied. According to the modulation frequency of thermal excitation and the sampling frequency of infrared imaging, the total number of scales used in wavelet transform was selected adaptively, and then a phase image sequence was reconstructed from the raw thermal image sequence by using the complex Morlet wavelet coefficients. An experiment of modulated thermography was performed on a glass fiber reinforced plastic reference sample containing delamination defects, the application effects of the method were quantitatively evaluated and compared with the Fourier transform method by the signal-to-noise ratio. The results show that the complex Morlet wavelet phase method can separate the low frequency and high frequency noise from the thermal image signal, and extract the subsurface defects at different depth robustly; it keeps a good tolerance to the change of the modulation frequency; so it is an effective algorithm of the modulated thermography.
引文
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[11]Guo Xingwang,Li Ransheng,Ding Mengmeng.Simulating modulated thermography of cladding debond in solid rockets[J].Journal of Mechanical Engineering,2011,47(2):9-15.(in Chinese)郭兴旺,李苒笙,丁蒙蒙.固体火箭包覆层脱粘调制红外热波检测法的数值模拟[J].机械工程学报,2011,47(2):9-15.
[2]Siddiqui J A,Arora V,Mulaveesala R,et al.Infrared thermal wave imaging for nondestructive testing of fibre reinforced polymers[J].Experimental Mechanics,2015,55(7):1239-1245.
[3]Vavilov V.Thermal NDT:historical milestones,state-of-theart and trends[J].Quantitative Infrared Thermography Journal,2014,11(1):66-83.
[4]Delanthabettu S,Menaka M,Venkatraman B,et al.Defect depth quantification using lock-in thermography[J].Quantitative Infrared Thermography Journal,2015,12(1):37-52.
[5]Liu Junyan,Dai Jingmin,Wang Yang.Theory and experiment of IR lock-in thermography with image sequence processing[J].Infrared and Laser Engineering,2009,38(2):346-351.(in Chinese)刘俊岩,戴景民,王扬.红外图像序列处理的锁相热成像理论与试验[J].红外与激光工程,2009,38(2):346-351.
[6]Mallat S G.A Theory for multiresolution signal decomposition:the wavelet representation[J].IEEE Transactions on Pattern Analysis&Machine Intelligence,1989,11(7):674-693.
[7]Ba Guijie.Research on infrared image characteristics and applications based on generalized wavelet transform[D].Harbin:Harbin Institute of Technology,2010:40-55.(in Chinese)巴桂洁.基于广义小波变换的红外图象特性分析及应用研究[D].哈尔滨:哈尔滨工业大学,2010:40-55.
[8]Galmiche F,Maldague X.Depth defect retrieval using the wavelet pulsed phased thermography[C]//Proceedings of the5th Conference on Quantitative Infrared Thermography(QIRT),2000:036.
[9]Guo Wei,Dong Lihong,Wang Haidou,et al.Phase spectra extract of thermal wave with wavelet decomposition and coating thickness estimation[J].Infrared and Laser Engineering,2017,46(9):0904003.(in Chinese)郭伟,董丽虹,王海斗,等.基于小波分解的热波相位特征提取及喷涂层厚度评价[J].红外与激光工程,2017,46(9):0904003.
[10]Robert Olbrycht,Boguslaw Wiecek,Grzegorz Gralewicz,et al.Comparison of Fourier and wavelet analyses for defect detection in lock-in and pulse phase thermography[J].Quantitative Infrared Thermography Journal,2007,4(2):219-232.
[11]Guo Xingwang,Li Ransheng,Ding Mengmeng.Simulating modulated thermography of cladding debond in solid rockets[J].Journal of Mechanical Engineering,2011,47(2):9-15.(in Chinese)郭兴旺,李苒笙,丁蒙蒙.固体火箭包覆层脱粘调制红外热波检测法的数值模拟[J].机械工程学报,2011,47(2):9-15.