Abstract: This article introduces the principle of structure damage identification based on phased array and Lamb wave technology. A single mode Lamb wave is excited by selecting a suitable low frequency narrow bandwidth signal. Then it is combined with ultrasonic phased array theory to monitor the structure condition and identify the damage in the structure multidirectionally. In view of the imperfection of the damage image, the method of point-to-point based contrast enhancement is used to improve the image quality and enhance the image identifiable degree as well as the image resolution. Finally, the proposed method is verified by experiments on composite material and aluminum sheet structures for different types of damage and the results show that it is effective in identifying the damage position of structure and enhancing the image identifiable degree.

Key words: structural health monitoring, image enhancement, phased array, phase delay, damage image