scholarly journals The Influence of the Grid Density of Measurement Points on Damage Detection in an Isotropic Plate by the Use of Elastic Waves and Laser Scanning Doppler Vibrometry

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7394
Author(s):  
Łukasz Doliński ◽  
Marek Krawczuk ◽  
Magdalena Palacz ◽  
Wiktor Waszkowiak ◽  
Arkadiusz Żak
Keyword(s):  
Damage Detection ◽  
Elastic Waves ◽  
Laser Scanning ◽  
Diagnostic Methods ◽  
Mode Shapes ◽  
Engineering Practice ◽  
Natural Vibrations ◽  
Spectral Finite Element Method ◽  
The Time Domain ◽  
Spectral Finite Element

Damage detection in structural components, especially in mechanical engineering, is an important element of engineering practice. There are many methods of damage detection, in which changes in various parameters caused by the presence of damage are analysed. Recently, methods based on the analysis of changes in dynamic parameters of structures, that is, frequencies or mode shapes of natural vibrations, as well as changes in propagating elastic waves, have been developed at the highest rate. Diagnostic methods based on the elastic wave propagation phenomenon are becoming more and more popular, therefore it is worth focusing on the improvement of the efficiency of these methods. Hence, a question arises about whether it is possible to shorten the required measurement time without affecting the sensitivity of the diagnostic method used. This paper discusses the results of research carried out by the authors in this regard both numerically and experimentally. The numerical analysis has been carried out by the use of the Time-domain Spectral Finite Element Method (TD-SFEM), whereas the experimental part has been based on the measurement performed by 1-D Laser Doppler Scanning Vibrometery (LDSV).

Vibration-Based Damage Detection Techniques for Health Monitoring of Construction of a Multi-Storey Building

2018 ◽  
Vol 931 ◽  
pp. 178-183 ◽  
Author(s):  
Yuriy Y. Shatilov ◽  
Alexander A. Lyapin
Keyword(s):  
Damage Detection ◽  
Damage Index ◽  
The State ◽  
Diagnostic Methods ◽  
Detection Methods ◽  
Mode Shapes ◽  
Dynamic Parameters ◽  
Labor Costs ◽  
Detection Techniques ◽  
Storey Building

Conducting surveys of multi-storey buildings is a laborious task, because large volumes of visual and instrumental research should be carried out. Reduction of labor costs with an increase in the reliability of information about the state of damage and technical condition is an actual scientific and practical task. One of the ways to solve it is to use non-destructive vibration diagnostic methods. The purpose of carrying out diagnostics with the use of vibration based damage detection methods is to search for damages in structural elements that can cause the deviation of the dynamic parameters of a structure from calculated ones. Determination of the dynamic parameters of the structure, in particular natural frequencies and mode shapes of mechanical systems, is one of the most important tasks that allows obtaining integral information about the state of a structure. This article presents the results of calculations for the localization of slabs defects in a multi-storey building with a transverse crack, span L = 4.5 (m), height H = 0.2 (m), with prestressed reinforcement d = 0.05 (m). Vibration based Damage Index method was used to localize the defect. During the study, reliable localization values of the defect area of the slab were obtained, this indicates that the vibration method for determining the damage index with a sufficient degree of accuracy allowed predicting the site of damage to the structure.

scholarly journals Damage Detection in Grid Structures Using Limited Modal Test Data

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Bei-dou Ding ◽  
Da-shuai Feng ◽  
Heng-lin Lv ◽  
Xian Li
Keyword(s):  
Damage Detection ◽  
Test Data ◽  
Column Vector ◽  
Mode Shapes ◽  
Engineering Practice ◽  
Frobenius Norm ◽  
Three Dimension ◽  
Grid Structure ◽  
Modal Strain Energy ◽  
Modal Test

The detection of potentially damaged elements in grid structures is a challenging topic. By using limited measured test data, damage detection for grid structures is developed by the modal strain energy (MSE) method. Two critical problems are considered in this paper in developing the MSE method to detect potential damage to the grid structure by using limited modal test data. First, an updated mode shape expansion method based on the modal assurance criterion is adopted to ensure that the modal shape obtained from the reference baseline model is reliable and has explicit physical meanings. Second, after identifying the location of the element damage by the element MSE method with expanded mode shapes, multivariable parameters denoting element damage severity are simultaneously determined. These parameters are included in the column vector and matched with the corresponding element stiffness matrix while the error tolerance value of the Frobenius norm of the column vector is undercontrolled. Finally, a three-dimension numerical model of the grid structure is used to represent different damage cases and to demonstrate the effectiveness of the present method. The application of the three-dimension physical model to a full-scale grid structure is also verified. Analysis results demonstrate that the presented damage detection method effectively locates and quantifies single- and multimember damage in grid structures and can be applied in engineering practice.

Multi-Phased Array for Damage Localisation

2007 ◽  
Vol 347 ◽  
pp. 77-82 ◽  
Author(s):  
Pawel Malinowski ◽  
Tomasz Wandowski ◽  
Irina Trendafilova ◽  
Wiesław M. Ostachowicz
Keyword(s):  
Elastic Waves ◽  
Phased Array ◽  
Numerical Data ◽  
Beam Forming ◽  
Phase Array ◽  
Angular Difference ◽  
Stiffness Reduction ◽  
Spectral Finite Element Method ◽  
The Difference ◽  
Spectral Finite Element

A method for damage localisation has been developed, which is based on the phased array idea. Four arrays of transducers, instead of only one, are used to perform a beam-forming procedure. Each array consists of nine transducers placed along a line, which are able to excite and register elastic waves. The arrays are placed in such a way that the angular difference between them is 45º and the rotation point is the middle transducer, which is common for all the arrays. The idea has been tested on a square aluminium plate modelled by the Spectral Finite Element Method. Two types of damage were considered, namely distributed damage, which was modelled as stiffness reduction, and cracks, modelled as separation of nodes in selected finite elements. The plate is excited by a wave packet (5-cycle sine modulated by the Hanning window). The whole array system is placed in the middle of the plate. Each phase array in the system acts independently and produces maps of a scanned field based on the beam-forming procedure. These maps are made of signals that represent the difference between the damaged plate signals and those from the intact plate. An algorithm was developed to join all four maps. This procedure eliminates the necessity to analyse each map individually and also gives the possibility to extract common features only. It allows to remove ambiguity and helps to localise damage more precisely than in the case of a single map. The problem for damage localisation was investigated and exemplary maps confirming the effectiveness of the system proposed were obtained. The investigation is based exclusively on numerical data.

High Fidelity Methods for Modeling Nonlinear Wave Propagation in One-Dimensional Waveguides

2012 ◽  
Author(s):  
Yu Liu ◽  
Pooya Ghaderi ◽  
Andrew J. Dick
Keyword(s):  
Wave Propagation ◽  
Perturbation Method ◽  
Frequency Component ◽  
Constitutive Law ◽  
Nonlinear Wave Propagation ◽  
Nonlinear Force ◽  
Spectral Finite Element Method ◽  
The Time Domain ◽  
Spectral Finite Element ◽  
Dynamic Shape

In this paper, two new methods are proposed to study wave propagation in materials with constitutive law that have nonlinear terms. In the first method, the gauge transformation is used to derive the dynamic shape function. A perturbation method is then applied in order to derive an equation for the wavenumber. The influence of the nonlinearity takes the form of a dependence of the wavenumber on the magnitude of the corresponding frequency component. Under the small amplitude and weak nonlinearity assumptions of the perturbation method, the wavenumber is incorporated into the spectral finite element method (SFEM). The second approach is a numerical method based on alternating frequency-time (AFT) iterations. The nonlinear term represented as a residual nonlinear force term is reduced through the alternating iterations between the time-domain and the frequency-domain. Finally, response behaviors under impact loading predicted with these methods are studied and compared to equivalent linear response behavior.

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