scholarly journals An Inverse Approach of Damage Identification Using Lamb Wave Tomography

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2180 ◽  
Author(s):  
Yaolu Liu ◽  
Shijie Zhou ◽  
Huiming Ning ◽  
Cheng Yan ◽  
Ning Hu
Keyword(s):  
Damage Identification ◽  
Lamb Waves ◽  
Damage Index ◽  
Least Square Method ◽  
Reconstruction Algorithm ◽  
Least Square ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Inverse Approach ◽  
Wave Tomography

A pulse laser combined LWT technique with a two-stage reconstruction algorithm was proposed to realize rapid damage location, or even the evaluation of damage size for plate-like structures. Since the amplitude of Lamb waves in propagation is highly sensitive to damage, including inside damage, the change of the attenuation coefficient of Lamb waves in the inspection region was used as a damage index to reconstruct damage images. In stage one, the rough area of the damage was identified by a comparison of the amplitude of the testing signal data and reference data (undamaged state). In stage two, the damage image was reconstructed using an inverse approach based on the least-square method. In order to verify the effectiveness of the proposed rapid approach, experiments on an aluminum plate with a non-penetrating notch and a carbon fiber-reinforced plastic laminated plate with internal delamination induced by a low-velocity impact were carried out. The results show that the notch can be detected with accurate location, and the delamination image can be reconstructed successfully.

Damage Index Comparison for a Composite Stiffened Panel Using Lamb Wave

2007 ◽  
Vol 26-28 ◽  
pp. 1265-1268 ◽  
Author(s):  
Chan Yik Park
Keyword(s):  
Lead Zirconate Titanate ◽  
Lamb Waves ◽  
Impact Damage ◽  
Damage Index ◽  
Lead Zirconate ◽  
Low Velocity Impact ◽  
Stiffened Panel ◽  
Low Velocity ◽  
Composite Stiffened Panel ◽  
Index Comparison

Various damage index (DI) algorithms of detecting changes such as a loosen bolt and a delamination development in a composite structure were examined using ultrasonic Lamb waves generated by embedded piezoelectric active sensors. The DI is a single value that is a function of response signal’s attenuation due to any damage or changes in a structure. Various DI algorithms such as active damage interrogation (ADI), time domain root men square (RMS), short time Fourier Transform (STFT) and time reversal (TR) were discussed. For experimental validation, a composite stiffened panel was used, and loosen bolt damage and low-velocity- impact damage were tested. In order to pitch and catch Lamb waves, surface mounted PZTs (lead zirconate titanate) were used. According to the DI algorithms, appropriate ultrasonic guided Lamb waves were selected for actuators. Each set of DI algorithm and drive signal showed different characteristics to detect the damage.

scholarly journals A Method for Reconstruction of Boiler Combustion Temperature Field Based on Acoustic Tomography

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yuhui Wu ◽  
Xinzhi Zhou ◽  
Li Zhao ◽  
Chenlong Dong ◽  
Hailin Wang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Optimal Parameter ◽  
Interpolation Method ◽  
Least Square Method ◽  
Reconstruction Algorithm ◽  
Least Square ◽  
Temperature Fields ◽  
Acoustic Tomography ◽  
Measured Temperature

Acoustic tomography (AT), as a noninvasive temperature measurement method, can achieve temperature field measurement in harsh environments. In order to achieve the measurement of the temperature distribution in the furnace and improve the accuracy of AT reconstruction, a temperature field reconstruction algorithm based on the radial basis function (RBF) interpolation method optimized by the evaluation function (EF-RBFI for short) is proposed. Based on a small amount of temperature data obtained by the least square method (LSM), the RBF is used for interpolation. And, the functional relationship between the parameter of RBF and the root-mean-square (RMS) error of the reconstruction results is established in this paper, which serves as the objective function for the effect evaluation, so as to determine the optimal parameter of RBF. The detailed temperature description of the entire measured temperature field is finally established. Through the reconstruction of three different types of temperature fields provided by Dongfang Boiler Works, the results and error analysis show that the EF-RBFI algorithm can describe the temperature distribution information of the measured combustion area globally and is able to reconstruct the temperature field with high precision.

scholarly journals A New Algorithm for Reconstructing Two-Dimensional Temperature Distribution by Ultrasonic Thermometry

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Xuehua Shen ◽  
Qingyu Xiong ◽  
Weiren Shi ◽  
Shan Liang ◽  
Xin Shi ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Ultrasound Velocity ◽  
Least Square Method ◽  
Reconstruction Algorithm ◽  
Industrial Applications ◽  
Least Square ◽  
Distribution Models ◽  
Practical Applications ◽  
Reconstruction Performance ◽  
Reconstructed Temperature

Temperature, especially temperature distribution, is one of the most fundamental and vital parameters for theoretical study and control of various industrial applications. In this paper, ultrasonic thermometry to reconstruct temperature distribution is investigated, referring to the dependence of ultrasound velocity on temperature. In practical applications of this ultrasonic technique, reconstruction algorithm based on least square method is commonly used. However, it has a limitation that the amount of divided blocks of measure area cannot exceed the amount of effective travel paths, which eventually leads to its inability to offer sufficient temperature information. To make up for this defect, an improved reconstruction algorithm based on least square method and multiquadric interpolation is presented. And then, its reconstruction performance is validated via numerical studies using four temperature distribution models with different complexity and is compared with that of algorithm based on least square method. Comparison and analysis indicate that the algorithm presented in this paper has more excellent reconstruction performance, as the reconstructed temperature distributions will not lose information near the edge of area while with small errors, and its mean reconstruction time is short enough that can meet the real-time demand.

The Boiler Temperature Field Reconstruction Algorithm Based on Genetic Algorithm

2011 ◽  
Vol 88-89 ◽  
pp. 269-273
Author(s):  
Cheng Zhi Li ◽  
Fu Qun Shao ◽  
Zhe Kan ◽  
Hai Xiang Fan
Keyword(s):  
Genetic Algorithm ◽  
Temperature Field ◽  
Least Square Method ◽  
Reconstruction Algorithm ◽  
Acoustic Method ◽  
Least Square ◽  
Experimental Result ◽  
Field Reconstruction ◽  
Single Path ◽  
Temperature Field Reconstruction

The traditional power station boiler temperature field reconstruction algorithm is sensitive to the time of flight. In the boiler movement, the temperature field has symmetric distribution feature within the boiler. On the basis of the boiler temperature field reconstruction fundamental by using the acoustic method, the paper presents a new two dimension temperature field reconstruction algorithm, which combines the single path method and genetic algorithm. Firstly, the algorithm makes sure the temperature distribution by using single path function. It uses the points denote the temperatures on each path, and plots the mesh, which can represent the temperature preliminary distribution, by using the Bezier spline principle and linear multistep integration. Finally, the surface mesh is Interpolated and fitted by using genetic algorithm. The experimental result proved that, compared to the least square method, the new reconstruction algorithm has the feature of higher accuracy and higher reconstruction speed.

Measurements Selection for Bias Reduction in Structural Damage Identification

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Yuhang Liu ◽  
Shiyu Zhou ◽  
Yong Chen ◽  
Jiong Tang
Keyword(s):  
Structural Damage ◽  
Natural Frequencies ◽  
Damage Identification ◽  
Least Square Method ◽  
Linearization Method ◽  
Bias Reduction ◽  
Least Square ◽  
L1 Norm ◽  
Measurement Selection ◽  
Optimal Set

Linearization of the eigenvalue problem has been widely used in vibration-based damage detection utilizing the change of natural frequencies. However, the linearization method introduces bias in the estimation of damage parameters. Moreover, the commonly employed regularization method may render the estimation different from the true underlying solution. These issues may cause wrong estimation in the damage severities and even wrong damage locations. Limited work has been done to address these issues. It is found that particular combinations of natural frequencies will result in less biased estimation using linearization approach. In this paper, we propose a measurement selection algorithm to select an optimal set of natural frequencies for vibration-based damage identification. The proposed algorithm adopts L1-norm regularization with iterative matrix randomization for estimation of damage parameters. The selection is based on the estimated bias using the least square method. Comprehensive case analyses are conducted to validate the effectiveness of the method.

scholarly journals TAM and MUSIC Approach for Impact-Source Localization under Deformation Conditions

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3151
Author(s):  
Zhenghao Zhang ◽  
Yongteng Zhong ◽  
Jiawei Xiang
Keyword(s):  
Source Localization ◽  
Composite Structures ◽  
Lamb Waves ◽  
Laminate Plate ◽  
Location Estimation ◽  
Polar Coordinates ◽  
Low Velocity Impact ◽  
Estimation Accuracy ◽  
Low Velocity ◽  
The Impact

As an impact-source-localization technique, Lamb waves are commonly used to detect low-velocity impact in composite structures. However, the performance of Lamb waves is susceptible under deformation conditions. In this paper, a novel approach combined the Toeplitz approximation method (TAM) and multiple-signal classification (MUSIC) (TAM-MUSIC) to improve impact-source-localization (angle and distance in polar coordinates) accuracy under deformation conditions. The method divided a two-dimensional search of direction and distance into two one-dimensional searches. The impact direction was calculated by the TAM, which was introduced into the steering vector of MUSIC to estimate the distance by scanning the whole monitoring area. An epoxy laminate plate experiment showed that the phase and amplitude of uniform linear-array signals had different average plate curvature that led to poor impact-source-localization accuracy using the MUSIC method. TAM provided high-resolution direction-finding capability, suitable for the pretreatment of Lamb waves. Results showed that the present method, with a small amount of computation and low memory requirement, had higher location-estimation accuracy than that of traditional methods under deformation conditions.

Structural Health Monitoring of Composite Structures Using Guided Lamb Waves

2006 ◽  
Vol 321-323 ◽  
pp. 759-764 ◽  
Author(s):  
Krishnan Balasubramaniam ◽  
B.V. Soma Sekhar ◽  
J. Vishnu Vardan ◽  
C.V. Krishnamurthy
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Composite Structures ◽  
Lamb Waves ◽  
Impact Damage ◽  
Composite Plates ◽  
Structural Features ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Structural Health

Structural Health Monitoring (SHM) of aircrafts is of great relevance in the present age aircraft industry. The present study demonstrates three techniques that have the potential for the SHM of multi-layered composite structures. The first technique is based on multi-transmitter-multireceiver (MTMR) technique with tomographic methods used for data reconstruction. In the MTMR, the possibility of SHM using algebraic reconstruction techniques (ART) for tomographic imaging with Lamb wave data measured in realistic materials is examined. Defects (through holes and low velocity impact delaminations) were synthetic and have been chosen to simulate impact damage in composite plates. The second technique is a single-transmitter-multi-receiver (STMR) technique that is more compact and uses reconstruction techniques that are analogous to synthetic aperture techniques. The reconstruction algorithm uses summation of the phase shifted signals to image the location of defects, portions of the plate edges, and any reflectors from inherent structural features of the component. The third technique involves a linear array of sensors across a stiffener for the detection of disbanded regions.

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