Nondestructive health monitoring techniques for composite materials: A review

Structural health monitoring is the process of acquisition and analyzing technical data obtained from structures to determine the present condition of the structure and residual life. Composites have been widely in use because of their low weight and better mechanical properties compared to conventional metals. They are more prone to damage during cyclic loading and the impact of foreign objects. So, usage of the nondestructive techniques is important to detect such damage in composites at the beginning stage itself, which further helps to avoid catastrophic failure. Many review articles are discussing a single nondestructive technique to monitor the health of the structure, but a single technique is not sufficient in most of the cases. This review is focused on the most commonly used nondestructive health monitoring techniques such as acoustic emission, vibration testing, ultrasonic testing, infrared thermography, and shearography to detect and characterize the damage in composite structures used in aerospace, automotive, and marine applications. The comparison among the techniques also has been presented in this review.