Use of Relative Baseline Features of Guided Waves for In situ Structural Health Monitoring

2011 ◽  
Vol 22 (2) ◽  
pp. 175-189 ◽  
Author(s):  
Jeong-Seok Lee ◽  
Gyuhae Park ◽  
Chun-Gon Kim ◽  
Charles R. Farrar
Keyword(s):  
Environmental Conditions ◽  
Structural Damage ◽  
Guided Waves ◽  
Damage Identification ◽  
Lamb Waves ◽  
Processing Technique ◽  
Data Sets ◽  
Signal Processing Technique ◽  
Power Spectral ◽  
Aluminum Plates

This article presents a new signal-processing technique, which utilizes ‘‘relative baselines’’ instead of ‘‘pre-stored baselines,’’ for Lamb wave based SHM. Several successful SHM methods utilizing wave propagations usually involve recording baseline measurements and comparing them to a newly measured response for structural damage identification. However, maintaining an accurate database of baselines remains challenging because of the effects of varying environmental conditions. Therefore, in this study, the relative baseline concept is proposed, in which measured Lamb waves are correlated between different sensor-actuator sets, as opposed to being correlated to pre-stored baseline data. This study focuses on determining the feature best used for this relative baseline concept, and cross-correlation and power spectral density analysis techniques are performed on data sets recorded from composite and aluminum plates. Experiments are performed with these plates under the presence of temperature variations in order to demonstrate the capability of the relative baseline concept. Our experimental results clearly indicate that the proposed technique reduces the complications associated with using pre-stored baselines for SHM under varying environmental conditions, and provides a quantitative means of identifying structural damage.

Structural Health Monitoring of Thin Aluminum Plate Using Acoustic Sensors

2012 ◽  
Vol 622-623 ◽  
pp. 1389-1395
Author(s):  
R. Nishanth ◽  
K. Lingadurai ◽  
V. Malolan ◽  
Gowrishankar Wuriti ◽  
M.R.M. Babu
Keyword(s):  
Lamb Wave ◽  
Damage Identification ◽  
Lamb Waves ◽  
Time Domain Analysis ◽  
Ultrasonic Waves ◽  
Aluminum Plate ◽  
Identification System ◽  
Time Frequency ◽  
Thin Aluminum ◽  
Aluminum Plates

SHM is defined as “an emerging technology that can be defined as continuous, autonomous, real time, in-service monitoring of the physical condition of a structure by means of embedded or attached sensors with minimum manual intervention” .SHM provides the ability of a system to detect adverse changes within a system’s structure to enhance reliability and reduce maintenance costs. There are different Non-Destructive techniques like acoustic emission, ultrasonic, acousto-ultrasonic, guided ultrasonic waves or Lamb waves which are nowadays investigated for the development of an efficient and user-friendly damage identification system. This paper deals with the latter which is based on Lamb wave propagation. It has been developed especially for distinguishing different kinds of damages. The Lamb wave-based active SHM method uses piezoelectric (PZT) sensors to transmit and receive Lamb waves in a thin Aluminum plate. The Lamb wave modes (AO &SO) travel into the structure and are reflected by the structural boundaries, discontinuities, and damage. By studying their propagation and reflection, the presence of defect in the structure is determined. Laboratory level experiments have been carried out on thin Aluminum plates with angular, horizontal and vertical defect. The obtained waveform is filtered to avoid unwanted noise & disturbances using Savitzky-Golay filtering. The filtered waveforms are compared to differentiate the defects. Short Time Fourier Transform has been carried out on the acquired waveform. This study provides significant insight into the problem of identifying localized damages in the structure using PZT and dispersion of signal after they interact with different types of damage. Those small defects like the horizontal one that may be nearly missed in time domain analysis can also be clearly identified in the STFT analysis. Moreover the occurrence of So mode is also clearly seen. Thus, Lamb waves generated by PZT sensors and time-frequency analysis techniques could be used effectively for damage detection in aluminum plate. This study has given a complete idea of the working and the basic requirements of SHM system.

Damage Detection Using Lamb Waves (Review)

2014 ◽  
Vol 1028 ◽  
pp. 161-166 ◽  
Author(s):  
Zai Lin Yang ◽  
Hamada M. Elgamal ◽  
Yao Wang
Keyword(s):  
Damage Detection ◽  
Health Monitoring ◽  
Guided Waves ◽  
Damage Identification ◽  
Lamb Waves ◽  
Long Distance ◽  
The Past ◽  
Thin Walled Structures ◽  
Thin Walled ◽  
Analytical Complexity

Several techniques have been researched for detecting damage in plates. Each of these techniques offers their own unique advantages in detecting certain types of damage with various levels of analytical complexity. Lamb waves are guided waves that exist in thin walled structures. Because this type of wave can travel long distance with little attenuation, they have been studied intensively for structural health monitoring, especially in the past few decades. This paper presents an overview of using the Lamb waves in damage detection including the theory of lamb waves and the lamb-wave-based damage identification.

scholarly journals Nonlinear Guided Wave Tomography for Detection and Evaluation of Early-Life Material Degradation in Plates

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5498
Author(s):  
Chengwei Zhao ◽  
Sunia Tanweer ◽  
Jian Li ◽  
Min Lin ◽  
Xiang Zhang ◽  
...  
Keyword(s):  
Early Life ◽  
Guided Waves ◽  
Lamb Waves ◽  
Tone Burst ◽  
Guided Wave ◽  
Material Degradation ◽  
Third Order Elastic Constants ◽  
Metal Plates ◽  
Wave Tomography ◽  
Aluminum Plates

In this paper, the possibility of using nonlinear ultrasonic guided waves for early-life material degradation in metal plates is investigated through both computational modeling and study. The analysis of the second harmonics of Lamb waves in a free boundary aluminum plate, and the internal resonance conditions between the Lamb wave primary modes and the second harmonics are investigated. Subsequently, Murnaghan’s hyperelastic model is implemented in a finite element (FE) analysis to study the response of aluminum plates subjected to a 60 kHz Hanning-windowed tone burst. Different stages of material degradation are reflected as the changes in the third order elastic constants (TOECs) of the Murnaghan’s model. The reconstructed degradations match the actual ones well across various degrees of degradation. The effects of several relevant factors on the accuracy of reconstructions are also discussed.

Damage Identification Using Piezoelectric Impedance Measurement With Compressed Sensing Technique

2017 ◽  
Author(s):  
Pei Cao ◽  
Qi Shuai ◽  
Jiong Tang
Keyword(s):  
Compressed Sensing ◽  
Damage Identification ◽  
Impedance Measurement ◽  
Processing Technique ◽  
Detection Sensitivity ◽  
Computational Time ◽  
Test Problems ◽  
Impedance Change ◽  
Signal Processing Technique ◽  
Piezoelectric Impedance

During the last decades, extensive research has been conducted on structural health monitoring (SHM) techniques based on the changes of coupled structure properties, e.g. piezoelectric impedance, which enjoys high detection sensitivity due to high-frequency actuation/sensing nature. However, the actual identification of fault locations and severities remains to be challenging owing to underdetermined underling mathematics. Recently, compressed sensing, a signal processing technique originally developed to recover signals from the compressed measurements, has shown its potential to address some of the mathematical challenges encountered in SHM practices. In this research, we morph the impedance-based SHM problem into a compressed sensing scheme such that the impedance change are used as measured data to reconstruct the damage locations and severities through convex optimization, e.g. l1 optimization. The proposed approach offers practical attractions of only requiring a small number of measurements and a short amount of computational time, and the results are promising if certain properties are fulfilled. Finally, the proposed approach is applied to and validated by several test problems.

Structural Damage Identification Based on Information Fusion Techniques

2010 ◽  
Author(s):  
Hui Li ◽  
Yuequan Bao
Keyword(s):  
Damage Detection ◽  
Information Fusion ◽  
Structural Damage ◽  
Damage Identification ◽  
Yellow River ◽  
Numerical Study ◽  
Detection Methods ◽  
Data Sets ◽  
Structural Damage Detection ◽  
Selective Fusion

With the aim to decrease the uncertainties of structural damage detection, two fusion models are presented in this paper. The first one is a weighted and selective fusion method for combing the multi-damage detection methods based on the integration of artificial neural network, Shannon entropy and Dempster-Shafer (D-S) theory. The second one is a D-S based approach for combing the damage detection results from multi-sensors data sets. Numerical study on the Binzhou Yellow River Highway Bridge and an experimental of a 20-bay rigid truss structure were carried out to validate the uncertainties decreasing ability of the proposed methods for structural damage detection. The results show that both of the methods proposed are useful to decrease the uncertainties of damage detection results.

Lamb-Wave-Based Damage Identification in Laminated Composite Plates

2014 ◽  
Vol 1014 ◽  
pp. 3-8
Author(s):  
Zai Lin Yang ◽  
Hamada M. Elgamal ◽  
Jian Wei Zhang
Keyword(s):  
Lamb Wave ◽  
Structural Damage ◽  
Damage Identification ◽  
Lamb Waves ◽  
Laminated Composite ◽  
Composite Plates ◽  
High Sensitivity ◽  
Scattered Wave ◽  
Propagation Path ◽  
Laminated Composite Plates

With advantages including capability of propagation over a significant distance and high sensitivity to abnormalities and inhomogeneity near the wave propagation path, Lamb waves can be energised to disseminate in a structure and any changes in material properties or structural geometry created by a discontinuity, boundary or structural damage can be identified by examining the scattered wave signals. This paper presents an overview of the Lamb-wave-based damage identification in laminated composite plates including the formulation of lamb waves in an isotropic plate.

scholarly journals A Novel Complementary Method for the Point-Scan Nondestructive Tests Based on Lamb Waves

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Rahim Gorgin ◽  
Zhanjun Wu ◽  
Yuebin Zheng
Keyword(s):  
Lamb Wave ◽  
Test Piece ◽  
Damage Identification ◽  
Lamb Waves ◽  
Complementary Method ◽  
Nondestructive Tests ◽  
Damage Probability ◽  
Scan Test ◽  
Aluminum Plates ◽  
Probability Index

This study presents a novel area-scan damage identification method based on Lamb waves which can be used as a complementary method for point-scan nondestructive techniques. The proposed technique is able to identify the most probable locations of damages prior to point-scan test which lead to decreasing the time and cost of inspection. The test-piece surface was partitioned with some smaller areas and the damage probability presence of each area was evaluated.A0mode of Lamb wave was generated and collected using a mobile handmade transducer set at each area. Subsequently, a damage presence probability index (DPPI) based on the energy of captured responses was defined for each area. The area with the highest DPPI value highlights the most probable locations of damages in test-piece. Point-scan nondestructive methods can then be used once these areas are found to identify the damage in detail. The approach was validated by predicting the most probable locations of representative damages including through-thickness hole and crack in aluminum plates. The obtained experimental results demonstrated the high potential of developed method in defining the most probable locations of damages in structures.

Guided Waves Mode Filtering Using Fiber Bragg Grating Sensors

2021 ◽  
Author(s):  
Rohan Soman ◽  
Pawel Kudela ◽  
Maciej Radzienski ◽  
Wieslaw Ostachowicz
Keyword(s):  
Fiber Bragg Grating ◽  
Guided Waves ◽  
Processing Technique ◽  
Gauge Length ◽  
Uniform Strain ◽  
Bragg Grating ◽  
Large Area ◽  
Signal Processing Technique ◽  
Fbg Sensors ◽  
Limited Sensitivity

Abstract Guided waves (GW) allow fast inspection of a large area and hence have received great interest from the structural health monitoring (SHM) community. Fiber Bragg grating (FBG) sensors offer several advantages but their use for GW sensing has been limited due to their limited sensitivity. FBG sensors in the edge-filtering configuration have overcome this issue with sensitivity and there is a renewed interest in their use. It has been seen that depending on the ratio of the wavelength of the propagating wave to the gauge length of the FBG, the mechanism of the transduction of the wave measurement is different. A large ratio leads to a more uniform strain over the FBG leading to a shift in the frequency, while a non-uniform strain due to a short wavelength, leads to the peak widening. The present paper studies this phenomena and develops a signal processing technique for the filtering of the modes.

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