Open Access

ARTICLE

Multi-Mode Guided Waves Based Reference-Free Damage Diagnostic Imaging in Plates

Jiaqi Zhang¹, Kehai Liu^2,*, Chang Gao¹, Zhanjun Wu¹, Yuebin Zheng¹, Dongyue Gao³

1 State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian, 116024, China.
2 School of Civil Engineering, Dalian University of Technology, Dalian , 116024, China.
3 School of Aeronautics and Astronautics, Sun Yat-sen University, Guangzhou, 510275, China.

*Corresponding Author: Kehai Liu. Email: .

Structural Durability & Health Monitoring 2019, 13(1), 41-59. https://doi.org/10.32604/sdhm.2019.05142

Abstract

Probability-based diagnostic imaging (PDI) is one of the most well-known damage identification methods using guided waves. It is usually applied to diagnose damage in plates. The previous studies were dependent on the certain damage index (DI) which is always calculated from the guided wave signals. In conventional methods, DI is simply defined by comparing the real-time data with the baseline data as reference. However, the baseline signal is easily affected by varying environmental conditions of structures. In this paper, a reference-free diagnostic imaging method is developed to avoid the influence of environmental factors, such as temperature and load conditions. The DI is defined based on the mode conversion of multi-mode guided waves with real-time signals without baseline signals. To improve the accuracy of diagnosis, two terms are included in the reference-free DI. One is called energy DI, which is defined based on the feature of signal energy. The other is called correlation DI and is defined based on the correlation coefficient. Then the PDI algorithm can be carried out instantaneously according to the reference-free DI. The real-time signals which are used to calculate DI are collected by the piezoelectric lead zirconate titanate (PZT) transducers placed on both sides of a plate. The numerical simulations by the finite element (FE) method on aluminum plates with PZT arrays are performed to validate the effectiveness of the reference-free damage diagnostic imaging. The approach is validated by two different arrays: a circle network and a square network. The results of diagnostic imaging are demonstrated and discussed in this paper. Furthermore, the advantage of reference-free DI is investigated by comparing the accuracy of defined reference-free DI and energy DI.

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