scholarly journals Vibration Anatomy and Damage Detection in Power Transmission Towers with Limited Sensors

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1731
Author(s):  
R. Karami-Mohammadi ◽  
M. Mirtaheri ◽  
M. Salkhordeh ◽  
M. A. Hariri-Ardebili
Keyword(s):  
Wavelet Transform ◽  
Power Transmission ◽  
Low Cost ◽  
Structural Response ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Modal Assurance Criterion ◽  
Realistic Condition ◽  
Damage Scenarios ◽  
Transmission Towers

This study presents a technique to identify the vibration characteristics in power transmission towers and to detect the potential structural damages. This method is based on the curvature of the mode shapes coupled with a continuous wavelet transform. The elaborated numerical method is based on signal processing of the output that resulted from ambient vibration. This technique benefits from a limited number of sensors, which makes it a cost-effective approach compared to others. The optimal spatial location for these sensors is obtained by the minimization of the non-diagonal entries in the modal assurance criterion (MAC) matrix. The Hilbert–Huang transform was also used to identify the dynamic anatomy of the structure. In order to simulate the realistic condition of the measured structural response in the field condition, a 10% noise is added to the response of the numerical model. Four damage scenarios were considered, and the potential damages were identified using wavelet transform on the difference of mode shapes curvature in the intact and damaged towers. Results show a promising accuracy considering the small number of applied sensors. This study proposes a low-cost and feasible technique for structural health monitoring.

scholarly journals A System Identification-Based Damage-Detection Method for Gravity Dams

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Masoud Mirtaheri ◽  
Mojtaba Salkhordeh ◽  
Masoud Mohammadgholiha
Keyword(s):  
Wavelet Transform ◽  
Dynamic Properties ◽  
Structural Response ◽  
Cost Effective ◽  
The Body ◽  
Mode Shapes ◽  
Damage Scenarios ◽  
Hilbert Huang Transform ◽  
Random Decrement Technique ◽  
Random Decrement

Dams are essential infrastructures as they provide a range of economic, environmental, and social benefits to the local populations. Damage in the body of these structures may lead to an irreparable disaster. This paper presents a cost-effective vibration-based framework to identify the dynamic properties and damage of the dams. To this end, four commonly occurred damage scenarios, including (1) damage in the neck of the dam, (2) damage in the toe of the structure, (3) simultaneous damage in the neck and the toe of the dam, and (4) damage in the lifting joints of the dam, are considered. The proposed method is based on processing the acceleration response of a gravity dam under ambient excitations. First, the random decrement technique (RDT) is applied to determine the free-vibration of the structure using the structural response. Then, a combined method based on Hilbert–Huang Transform (HHT) and Wavelet Transform (WT) is presented to obtain the dynamic properties of the structure. Next, the cubic-spline technique is used to make the mode shapes differentiable. Finally, Continuous Wavelet Transform (CWT) is applied to the residual values of mode shape curvatures between intact and damaged structures to estimate the damage location. In order to evaluate the efficiency of the proposed method in field condition, 10% noise is added to the structural response. Results show promising accuracy in estimating the location of damage even when the structure is subjected to simultaneous damage in different locations.

Ambient vibrations for the assessment of the strengthening intervention of a masonry barrel vault

2020 ◽  
pp. 147592172095206
Author(s):  
Alice Di Primio ◽  
Noemi Fiorini ◽  
Daniele Spina ◽  
Claudio Valente ◽  
Marcello Vasta
Keyword(s):  
Dynamic Behavior ◽  
Ambient Vibration ◽  
Structural Monitoring ◽  
Mode Shapes ◽  
Modal Assurance Criterion ◽  
Existing Structures ◽  
Ambient Vibration Tests ◽  
2009 L’Aquila Earthquake ◽  
Historical Heritage ◽  
Vibration Tests

Vibration-based structural monitoring is a fundamental tool to assess the conditions of existing structures, in their real operating state. In particular, as concerns masonry buildings, although a large part of the Italian and European historical heritage is composed of vaulted structures, comparatively few papers in the literature are targeted to the study of the dynamic behavior of vaulted systems. The present work focuses on the application of vibration-based structural monitoring to a barrel vault of the Bussi Castle, located in Pescara, Italy, which suffered some damages as a consequence of the 2009 L’Aquila earthquake. Ambient vibration tests were carried out in the damaged state and after repair and strengthening of the vault for evaluating its dynamic behavior in both states. In either conditions, the modal parameters of the vault were identified using operational modal analysis techniques. The comparison of the modes in the two states, carried out with Modal Assurance Criterion index, clearly indicates an enhancement of dynamic behavior of the consolidated vault. In particular, a new index named Modal Symmetry Index is introduced. The index is based on a proper ratio between mode shapes to evaluate the improvement of the structural symmetry after the restoration interventions. The results confirm the effectiveness of the devised index to evaluate the strengthening interventions and, the potential of the structural monitoring to control the behavior of damaged vaulted masonry systems.

scholarly journals Ambient Vibration Testing of a Pedestrian Bridge Using Low-Cost Accelerometers for SHM Applications

Smart Cities ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 20-30 ◽  
Author(s):  
Azam Ali ◽  
Talha Sandhu ◽  
Muhammad Usman
Keyword(s):  
Finite Element ◽  
System Identification ◽  
Damage Detection ◽  
Low Cost ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Pedestrian Bridge ◽  
Finite Element Software ◽  
Ambient Vibration Testing ◽  
Good Comparison

Damage detection and structural health monitoring have always been of great importance to civil engineers and researchers. Vibration-based damage detection has several advantages compared to traditional methods of non-destructive evaluation, such as ground penetrating radar (GPR) or ultrasonic testing, since they give a global response and are feasible for large structures. Damage detection requires a comparison between two systems states, the baseline or “healthy state”, i.e., the initial modal parameters, and the damaged state. In this study, system identification (SI) was carried out on a pedestrian bridge by measuring the dynamic response using six low-cost triaxial accelerometers. These low-cost accelerometers use a micro-electro-mechanical system (MEMS), which is cheaper compared to a piezoelectric sensor. The frequency domain decomposition algorithm, which is an output-only method of modal analysis, was used to obtain the modal properties, i.e., natural frequencies and mode shapes. Three mode shapes and frequencies were found out using system identification and were compared with the finite element model (FEM) of the bridge, developed using the commercial finite element software, Abaqus. A good comparison was found between the FEM and SI results. The frequency difference was nearly 10%, and the modal assurance criterion (MAC) of experimental and analytical mode shapes was greater than 0.80, which proved to be a good comparison despite the small number of accelerometers available and the simplifications and idealizations in FEM.

Life Prediction of Electrical Power Transmission Towers

2008 ◽  
Author(s):  
Juan E. Salazar ◽  
Jesus A. Mendoza
Keyword(s):  
Transmission Line ◽  
Power Transmission ◽  
Electrical Power ◽  
Mode Shapes ◽  
Structural Members ◽  
Material Loss ◽  
State Of Stress ◽  
Transmission Towers ◽  
Load Effects ◽  
Stress And Deformation

This paper presents a study conducted to estimate the remaining theoretical life of one type of 400 kV latticed steel towers installed on a power transmission line in Venezuela. The study focused on determining the structural behavior and vibration characteristics of suspension towers on the fore mentioned line, considering material loss of their structural members due to atmospheric corrosion, in different design conditions. For this purpose, a commercially available FEM code was used to build models to perform structural and modal analysis of the chosen type of tower, in order to determine load effects in the structure (stress and deformation), natural frequencies and mode shapes in each of the different design states. Then, a simple methodology engineered as part of this study leads to prediction of the tower’s service life based on an allowable state of stress and deformation in the tower (direct and vibration-induced) affected by different reliability factors and taking into account corrosion effects and corrosion rates in a particular environment along the transmission line.

Ultrasonic unilateral double-position excitation lamb wave defect detection and quantification method for ground electrode of transmission tower

2021 ◽  
pp. 1-15
Author(s):  
Kuan Ye ◽  
Kai Zhou ◽  
Ren Zhigang ◽  
Ruizhe Zhang ◽  
Chunsheng Li ◽  
...  
Keyword(s):  
Guided Waves ◽  
Power Transmission ◽  
Geometric Model ◽  
Guided Wave ◽  
Quantization Error ◽  
Dispersion Function ◽  
Stable Operation ◽  
Transmission Tower ◽  
Ultrasonic Guided Wave ◽  
Transmission Towers

The power transmission tower’s ground electrode defect will affect its normal current dispersion function and threaten the power system’s safe and stable operation and even personal safety. Aiming at the problem that the buried grounding grid is difficult to be detected, this paper proposes a method for identifying the ground electrode defects of transmission towers based on single-side multi-point excited ultrasonic guided waves. The geometric model, ultrasonic excitation model, and physical model are established, and the feasibility of ultrasonic guided wave detection is verified through the simulation and experiment. In actual inspection, it is equally important to determine the specific location of the defect. Therefore, a multi-point excitation method is proposed to determine the defect’s actual position by combining the ultrasonic guided wave signals at different excitation positions. Besides, the precise quantification of flat steel grounding electrode defects is achieved through the feature extraction-neural network method. Field test results show that, compared with the commercial double-sided excitation transducer, the single-sided excitation transducer proposed in this paper has a lower defect quantization error in defect quantification. The average quantization error is reduced by approximately 76%.

Investigating the vibrational behaviour of a rotating two-blade propeller by using a self-tracking method

2018 ◽  
Vol 233 (3) ◽  
pp. 835-847 ◽  
Author(s):  
Mohammad-Reza Ashory ◽  
Farhad Talebi ◽  
Heydar R Ghadikolaei ◽  
Morad Karimpour
Keyword(s):  
Natural Frequency ◽  
Measurement Errors ◽  
Mode Shapes ◽  
Model Parameters ◽  
Test Results ◽  
Modal Assurance Criterion ◽  
Tracking Method ◽  
Strong Resemblance ◽  
Test Scenarios ◽  
Good Agreement

This study investigated the vibrational behaviour of a rotating two-blade propeller at different rotational speeds by using self-tracking laser Doppler vibrometry. Given that a self-tracking method necessitates the accurate adjustment of test setups to reduce measurement errors, a test table with sufficient rigidity was designed and built to enable the adjustment and repair of test components. The results of the self-tracking test on the rotating propeller indicated an increase in natural frequency and a decrease in the amplitude of normalized mode shapes as rotational speed increases. To assess the test results, a numerical model created in ABAQUS was used. The model parameters were tuned in such a way that the natural frequency and associated mode shapes were in good agreement with those derived using a hammer test on a stationary propeller. The mode shapes obtained from the hammer test and the numerical (ABAQUS) modelling were compared using the modal assurance criterion. The examination indicated a strong resemblance between the hammer test results and the numerical findings. Hence, the model can be employed to determine the other mechanical properties of two-blade propellers in test scenarios.

Study on Damage Detection of Bridge Based on Wavelet Multi-Scale Analysis

2013 ◽  
Vol 639-640 ◽  
pp. 1010-1014 ◽  
Author(s):  
Ke Ding ◽  
Ting Peng Chen
Keyword(s):  
Wavelet Transform ◽  
Damage Detection ◽  
Detection Method ◽  
Mode Shapes ◽  
Scale Analysis ◽  
Multi Scale ◽  
Damage Location ◽  
Transform Coefficients ◽  
Beam Bridge ◽  
Multi Scale Analysis

The damage detection method based on wavelet multi-scale analysis is presented in the paper. The damage location can be identified by analyzing the multi-scale wavelet transform coefficients of curvatures of mode shapes. The extreme value of wavelet transform coefficients indicates the damage location. But it is difficult to detect the location of defect if the defect is near to the equilibrium position of vibration. In order to solve this problem, we put forward a method which is to add the wavelet transform coefficients of multi modals together. The method can effectively overcome the above problem. Three damage situations of simply supported beam bridge are discussed in the paper. The results show that the peaks of wavelet transform coefficients indicate the damage location of structural. It is possible to pinpoint the damage location based on wavelet multi-scale analysis on curvatures of mode shapes.

Machine learning-based system for fault detection on anchor rods of cable-stayed power transmission towers

2021 ◽  
Vol 194 ◽  
pp. 107106
Author(s):  
M.S. Coutinho ◽  
L.R.G.S. Lourenço Novo ◽  
M.T. de Melo ◽  
L.H.A. de Medeiros ◽  
D.C.P. Barbosa ◽  
...  
Keyword(s):  
Machine Learning ◽  
Fault Detection ◽  
Power Transmission ◽  
Transmission Towers

A New Strategy for Detecting Gear Faults Using Denoising With the Orthogonal Discrete Wavelet Transform (ODWT)

1999 ◽  
Author(s):  
Sidi M. Berri ◽  
J. M. Klosner
Keyword(s):  
Wavelet Transform ◽  
Discrete Wavelet Transform ◽  
Power Transmission ◽  
Discrete Wavelet ◽  
Amplitude Noise ◽  
Transmission Pair ◽  
New Strategy ◽  
Band Pass ◽  
Local Defects ◽  
Low Amplitude

Abstract This paper investigates a new strategy for early detection of defects in a power transmission pair of spur gears. Sensitivity to local defects is enhanced by processing the signal as follows. The orthogonal discrete wavelet transform (ODWT) of the band-pass filtered averaged signal is first obtained. This is followed by thresholding in the wavelet domain, thereby removing the low amplitude noise contribution. The inverse wavelet transform then essentially reconstructs the component of the signal that is due to the defect. Experimental results demonstrate the efficiency of this procedure.

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