基于太赫兹图像的航天复合材料粘接缺陷检测方法研究

采用频率范围为0.23~0.32THz的反射式连续太赫兹波检测系统,对航天复合材料与基板的粘接缺陷进行了无损检测。采用环氧树脂作为粘接剂,制作了隔热复合材料与基板的粘接样件。使太赫兹波聚焦在粘接层处,获得层析图像,根据焦平面附近的图像,可直观判断出粘接面有无缺陷。结合中值滤波,采用模糊c均值(FCM)聚类算法对缺陷图像进行分割得到含有目标缺陷信息的二值图像,计算像素点得到缺陷面积。通过与已知缺陷面积样件对比,对粘接缺陷面积的预测误差在±9%以内。

Study on Nondestructive Testing for Bonding Defects in Aerospace Composite Based on Terahertz Image

Thermal insulation aerospace composite and metal substrates’ bonding defects are tested by the reflection type frequency modulated continuous terahertz wave testing system which the frequency range is 0.23-0.32THz. Thermal insulation composite and metal substrates are bonded by epoxy resin adhesive as the experimental sample. Bonding defects of the adhesive interface can be detected visualized by image neighbor focal plane. Otsu’s threshold algorithm and FCM clustering algorithm is applied to get the segment of defect binary images combined with median filtering, then have the defect area by calculating the number of pixels. Compared with the samples which have known defect area, the FCM clustering algorithm is finally used because of the better segmentation effect and the error is about ±5%.