相控阵超声监测成像与直方图匹配图像增强实验研究∗

摘要

he Lamb wave can directionally monitor the structure. The time delay of the signal is controlled in the process of transmitting and receiving. The normalized amplitudes of the scanning signals are drawn on a two-dimen-sional gray image to get the structural damage image. The original damage image is not perfect. The histogram matc-hing image enhancement method is used to improve the image recognition. Firstly,the gray level of the damage im-age is divided and the probability density function of the gray level is calculated. Secondly,the final gray transform relationship processed by histogram matching is gotten. Finally,the gray level of the original image is modified ac-cording to the gray level mapping relationship between the original image and the output image to obtain the contrast enhancement image. The method is conducted in the aluminum structure,the glass fiber-reinforced polymer and the carbon fiber-reinforced polymer to verify its correctness and effectiveness.%相控阵超声监测成像是通过控制Lamb波发射与接收的时间延迟而控制其指向，当特定方向的Lamb波指向结构中损伤时形成反射信号，由此监测结构中损伤；将监测结构扫描范围内不同方向上Lamb波信号的归一化幅值用二维灰度图像显示，实现结构损伤成像。由于相控阵监测所得原始图像并不完美，因此，利用直方图匹配图像增强方法对原始图像进行处理，通过划分损伤图像的灰度级、统计各灰度级的分布情况、计算各灰度级的概率密度函数，得到直方图匹配处理的最终灰度变换关系，利用原始图像与输出图像各灰度级的映射关系，修改原图像的灰度级，获得增强图像。该方法在铝板、玻璃纤维复合材料结构与碳纤维复合材料结构中进行实验分析，验证方法的正确性和有效性。