亚表面缺陷脉冲相位热成像检测技术

Evaluation of Subsurface Defect by Pulsed Phase Thermography

对脉冲相位热成像技术应用于亚表面缺陷的检测进行了实验研究,给出了铝合金和聚合物两种典型的金属和非金属试件的检测结果,并同传统红外热成像检测的对比度图像进行了对比。还对脉冲相位热成像检测技术中频谱分析的有关问题进行了分析,指出选择采集频率、采集窗口大小要考虑的影响因素,并分别采用组合平滑滤波、分段拟合的方法改善了相位变换的实际效果。结果表明脉冲相位辐射测量技术与一般光热辐射测量相比,测量结果明显改善,增强探测缺陷特别是深度缺陷的能力,减小加热不均等表面因素对测量的影响。

The experiment on the detection of subsurface defects by pulsed phase thermography（PPT） is studied. Two samples of different materials including aluminum and polymer are given. The experimental result is compared with the contrastive image of conventional thermography. The problems to fast Fourier transform（FFT） in PPT are studied. The effective factors for choosing the sampling frequency and truncation are given. Finally, by combining lowpass filters with subsection curve fitting, the result of the phase transform is improved. Result shows that compared with usual infrared thermography, the experimental result is evidently improved, detecting ability for the deep defect is enhanced and the influence on uneven heating surface is reduced.