A damage detection method for plate structures based on dynamic strain measurements

As one of the most used fundamental components, the plate structure is commonly employed in the civil and mechanical engineering fields. However, due to the harsh external environmental impact or manual factors, plate structures may be damaged during their design service life, which even threatens the safe operation of the overall system. Therefore, it is necessary to develop the health condition monitoring technique to diagnose the defect for the plate structure. In this paper, a theoretical model of the plate structure is derived based on the perturbation method to study the changes of the modal characteristics caused by the structural damages. It is found that the variation of strain mode shapes is sensitive to the damages. Based on this fact, a response-only diagnostic system for the plate structure is proposed that applies a fiber Bragg grating based strain sensing network to capture the dynamic response and then obtain the strain mode information from the captured response to locate the damage position. The performance of the proposed diagnostic system is validated by a laboratory test bed.