论文部分内容阅读
线性调频激励的红外热波成像检测技术是一种基于线性调制热波信号处理的主动式红外热成像技术,能够弥补传统红外锁相热像检测的单一调制热波只能探测相应扩散深度缺陷的不足,可准确检测不同深度范围内的缺陷形状及尺寸。阐述了线性调频红外热波成像检测技术的原理、分析方法和实验。采用有限元方法对线性调频啁啾(Chirp)规律变化热流在构件中的传递过程进行了分析。利用相关算法计算了表面温度(热波)信号的相关峰值及其对应的时间,形成了表面温度相关峰值图像与峰值时间图像。利用Chirp规律调制卤素光源作为热激励源对金属平底孔试件进行激励加载,通过Jade MWIR 550焦平面红外热像仪进行图像序列采集。分别利用时域相关处理与频域FFT扫描得到了表面温度(热波)信号的相关峰值及对应时间图像和不同频率下的相位图像。试验结果表明,在给定激励条件下,相关峰值图像和频域相位图像能够可靠地确定不同深度缺陷的几何特征。
Linear frequency modulation excitation infrared thermal imaging detection technology is based on a linear modulation heat wave signal processing of active infrared thermal imaging technology to make up for the traditional infrared phase-locked thermal imaging detection of a single modulation heat wave can only detect the corresponding diffusion depth defects Insufficient, can accurately detect different depths of the defect shape and size. The principle, analysis method and experiment of LFMIR detection technology are expounded. The finite element method was used to analyze the chirp-law heat transfer in the member. Correlation algorithm was used to calculate the relative peak value of the surface temperature (heat wave) signal and its corresponding time, and the surface temperature-related peak image and peak time image were formed. Chirp law was used to modulate the halogen light source as a heat excitation source for the metal flat-bottomed hole specimen excitation loading, image sequence acquisition by Jade MWIR 550 focal plane thermal imaging camera. The correlation peak of the surface temperature (heat wave) signal and corresponding time images and phase images under different frequencies were obtained by time domain correlation processing and frequency domain FFT scanning respectively. The experimental results show that the correlation peak images and the frequency domain phase images can reliably determine the geometric characteristics of different depth defects under given excitation conditions.