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Use of delay and sum for sparse reconstruction improvement for structural health monitoring
, Article Journal of Intelligent Material Systems and Structures ; Volume 30, Issue 18-19 , 2019 , Pages 2919-2931 ; 1045389X (ISSN) ; Navazi, H. M ; Groves, R. M ; Sharif University of Technology
SAGE Publications Ltd
2019
Abstract
To perform active structural health monitoring, guided Lamb waves for damage detection have recently gained extensive attention. Many algorithms are used for damage detection with guided waves and among them, the delay-and-sum method is the most commonly used algorithm because of its robustness and simplicity. However, delay-and-sum images tend to have poor accuracy with a large spot size and a high noise floor, especially in the presence of multiple damages. To overcome these problems, another method that is based on sparse reconstruction can be used. Although the images produced by the sparse reconstruction method are superior to the conventional delay-and-sum method, it has the challenges...
Using the hybrid DAS-SR method for damage localization in composite plates
, Article Composite Structures ; Volume 247 , 2020 ; Navazi, H. M ; Groves, R. M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this paper, the hybrid Delay-And-Sum (DAS) with Sparse Reconstruction (SR) method was further developed for damage location in composite plates. In composite materials, anisotropy leads to some challenges in using conventional damage location methods, which are developed for isotropic materials. In the hybrid DAS-SR method, the DAS and SR methods were combined as a complement of each other. To investigate the DAS-SR method for composite structures, the group velocity of the travelling wave for different directions was first measured experimentally via PZTs. The DAS and SR formulations were then modified to be compatible with the direction-dependent group velocities. The results show that...
Evaluation of the sparse reconstruction and the delay-and-sum damage imaging methods for structural health monitoring under different environmental and operational conditions
, Article Measurement: Journal of the International Measurement Confederation ; Volume 169 , 2021 ; 02632241 (ISSN) ; Navazi, H. M ; Groves, R. M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
In this paper, the performance of the sparse reconstruction (SR) and the delay-and-sun (DAS) methods for damage localization, were evaluated for various environmental and operational conditions, both numerically and experimentally. To assess these damage localization methods, a methodology based on the Taguchi method was used to make the experimental design, and a modified performance-index was defined to represent the quality of reconstructed images. Then, the robustness and the accuracy of each method, in a well-defined performance region relevant to in-service aerospace structures, were investigated using the Taguchi and analysis of variance methods. It was concluded that for the defined...
Developing Hybrid Das-Sr Method for Structural Health Monitoring Using Guided Lamb Waves and Sparse Array of Pzt Transducers with Experimental Validation
, Ph.D. Dissertation Sharif University of Technology ; Mohammad Navazi, Hossein (Supervisor)
Abstract
The main purpose of this dissertation is to investigate and improve the efficiency of Sparse Reconstruction method for structural health monitoring application in order to solve the challenges including; finding multiple simultaneous damages, damage detection and location in anisotropic structures and real engineering complex structures. The main approach of this research is based on presenting theoretical concepts and developing practical methods based on the presented concepts, as well as evaluating and implementing the developed methods using numerical simulations and experimental tests. In this work, the finite element method is used for numerical simulation. In the experimental test,...