Modal analysis and damage localization in plate-type structures via TDD and PE methods based on the data of an integrated highspeed camera system

Abstract

With the fast development of full-field vibration measurements by combining digital image correlation (DIC) technique with the integrated highspeed camera system, the structural characteristic deflection shapes (CDS’s) can be readily captured, which are sensitive for damage localization. Naturally, the mode shapes are preferred due to their higher signal to noise ratio. However, traditional modal analysis methods are inefficient in processing the large volumes of data that acquired by high-speed camera system for mode shape-based damage localization. Moreover, how to extract the damage features and enhance the damage localization results without the baseline-data of the intact state is another challenging issue. To address these problems, a novel damage localization method is proposed by enhancing the mode shape estimation and optimizing the damage feature extraction. Firstly, the dominant singular vector at each interested resonant frequency is individually evaluated as the mode shapes in the proposed time domain decomposition (TDD) method. Moreover, based on the extracted mode shapes, a pseudo-excitation (PE) method is proposed to reveal the damage locations without baseline-data by examining the perturbation of local dynamic equilibrium. To circumvent the effects of measurement noise on PE method, an adaptive denoising technique is proposed based on Gaussian smoothing. Furthermore, the local contiguity and spatial sparsity of the damage-caused features are harnessed by a hierarchical clustering to optimize the damage localization performance via tuning the scale parameter of Gaussian smoothing. Finally, numerical and experimental studies of crack damaged plates are conducted to validate the feasibility and effectiveness of the proposed mode shape estimation and damage localization methods. During the experiment, the full-field vibration measurements are acquired by using an integrated binocular highspeed camera system. In addition, a comparison study based on benchmark data is carried out to demonstrate the performance and reliability of the proposed damage localization method.