根据某型固体火箭发动机钢壳体/橡胶绝热层的实际结构特点,制作了含6个脱粘缺陷的壳状实验样本,基于脉冲式红外热波方法进行了检测研究。针对实验获取的红外热图存在“非均匀受热、表面反射、噪音大、对比度低”等问题,采用去除背景和高频强调滤波等方法对原始热图进行非均匀性校正和图像增强处理,基于数学形态学的分水岭方法实现了缺陷位置和大小的识别。结果表明:红外热波技术能够有效检测壳状结构的缺陷,非常适用于实际火箭发动机壳体/绝热层结构的检测:其检测效率较高、检测结果直观、对缺陷的定位准确;缺陷直径16mm时,钢壳体的检测深度达到4mm,基本能够满足固体火箭发动机的工程检测需求。
According to the actual shell structure characteristic of Solid Rocket Motor (SRM), a specimen with shell shape including 6 debond defects was manufactured, which was detected by pulse infrared thermography. For the problem of non-uniformity, surface reflection, high noise and low contrast of the infrared images acquired by the infrared thermal camera, image correction, enhancement and segmentation algorithms were used to enhance the image quality and segment the defect from the background. Finally, the defect location, size and depth were estimated quantitatively by using watershed algorithm of mathematical morphology. The results show that thermal wave technique has more advantages such as high-efficiency, non-contact, identifying defect location more accurately than other methods, and it is also very applicable to complicated shell adhesion structure. Debond with diameter of 16 mm at the depth of 4 mm is easy to be detected, which could satisfy the requirement of SRM.