scholarly journals The Rapid Detection Technology of Lamb Wave for Microcracks in Thin-Walled Tubes

2019 ◽  
Vol 9 (17) ◽  
pp. 3576 ◽  
Author(s):  
Yang ◽  
Wang ◽  
Yang
Keyword(s):  
Lamb Wave ◽  
Rapid Detection ◽  
Detection Method ◽  
Lamb Waves ◽  
Thin Plates ◽  
Depth Information ◽  
Amplitude Curve ◽  
Dispersion Characteristics ◽  
Detection Technology ◽  
Thin Walled

Thin-walled tubes are a kind of pressure vessel formed by a stamping and drawing process, which must withstand a great deal of sudden pressure during use. When microcrack defects of a certain depth are present on its inner and outer surfaces, severe safety accidents may occur, such as cracking and crushing. Therefore, it is necessary to carry out nondestructive testing of thin-walled tubes in the production process to eliminate the potential safety hazards. To realize the rapid detection of microcracks in thin-walled tubes, this study could be summarized as follows: (i) Because the diameters of the thin-walled tubes were much larger than their thicknesses, Lamb wave characteristics of plates with equal thicknesses were used to approximate the dispersion characteristics of thin-walled tubes. (ii) To study the dispersion characteristics of Lamb waves in thin plates, the detection method of the mode was determined using the particle displacement–amplitude curve. (iii) Using a multi-channel parallel detection method, rapid detection equipment for Lamb wave microcracks in thin-walled tubes was developed. (iv) The filtering peak values for defect signal detection with different depths showed that the defect detection peak values could reflect the defect depth information. (v) According to the minimum defect standard of a 0.045-mm depth, 100,000 thin-walled tubes were tested. The results showed that the missed detection rate was 0%, the reject rate was 0.3%, and the detection speed was 5.8 s/piece, which fully meets the actual detection requirements of production lines. Therefore, this study not only solved the practical issues for the rapid detection of microcracks in thin-walled tubes but also provided a reference for the application of ultrasonic technology for the detection of other components.

Finite Element Simulation of Lamb Wave with Piezoelectric Transducers for Composite Plate Damage Detection

2009 ◽  
Vol 79-82 ◽  
pp. 1095-1098 ◽  
Author(s):  
Wen Zhong Qu ◽  
Li Xiao
Keyword(s):  
Finite Element ◽  
Damage Detection ◽  
Finite Element Simulation ◽  
Lamb Wave ◽  
Composite Plate ◽  
Lamb Waves ◽  
Piezoelectric Transducers ◽  
Thin Plates ◽  
Diagnostic Tools ◽  
Element Simulation

Structural health monitoring (SHM) is an emerging research area with multiple applications. Lamb waves are ultrasonic elastic waves that travel inside and along thin plates and is frequently used as diagnostic tools to detect damage in plate-like structures. In this paper, a transient dynamic finite element simulation of Lamb wave with piezoelectric transducers for damage detection in a composite plate is carried out. The embedded cross-shaped piezoelectric active sensor arrays were used to generate and receive guided Lamb waves propagating in the plate structure. A full-scale FEM model for the laminate was created using three-dimensional eight-node layered structural solid element and piezoelectric active sensors were created using coupled field elements on the commercial finite element code ANSYS platform. The beam forming technique of Lamb waves is used to locate damage in the plate .The results of the numerical simulation demonstrate the effectiveness of the approach.

scholarly journals Nonpenetrating Damage Identification Using Hybrid Lamb Wave Modes from Hilbert-Huang Spectrum in Thin-Walled Structures

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Zijian Wang ◽  
Pizhong Qiao ◽  
Binkai Shi
Keyword(s):  
Lamb Wave ◽  
Damage Identification ◽  
Lamb Waves ◽  
Wave Mode ◽  
Thin Walled Structures ◽  
Damage Indices ◽  
Thin Walled ◽  
Experimental Validations ◽  
The One ◽  
Wave Modes

Lamb waves have shown promising advantages for damage identification in thin-walled structures. Multiple modes of Lamb wave provide diverse sensitivities to different types of damage. To sufficiently utilize damage-related wave features, damage indices were developed by using hybrid Lamb wave modes from Hilbert-Huang spectra. Damage indices were defined as surface integrals of Hilbert-Huang spectra on featured regions determined by time and frequency windowing. The time windowing was performed according to individual propagation velocity of different Lamb wave mode, while the frequency windowing was performed according to the frequency of excitation. By summing damage indices for all transmitter-receiver pairs, pixels were calculated to reconstruct a damage map to characterize the degree of damage at each location on structure. Both numerical and experimental validations were conducted to identify a nonpenetrating damage. The results demonstrated that the proposed damage indices using hybrid Lamb wave modes are more sensitive and robust than the one using single Lamb wave mode.

Damage Detection in Thick Steel Beam Using Lamb Waves

2008 ◽  
Author(s):  
Kai Sun ◽  
Guang Meng ◽  
Fucai Li ◽  
Lin Ye ◽  
Ye Lu
Keyword(s):  
Damage Detection ◽  
Lamb Wave ◽  
Lamb Waves ◽  
Fem Simulation ◽  
Wave Mode ◽  
Thin Plates ◽  
Steel Beams ◽  
Thick Steel ◽  
Number Of Cycles ◽  
Detection And Localization

Different from the mostly concerned Lamb wave-based damage detection for thin plates, this paper presents a diagnosis procedure on thick steel beams with thickness of 34 mm. The diagnosis strategy and specimens were first described, and some parameters, such as the frequency and the number of cycles of the diagnostic waveform, were discussed. Based on finite element method (FEM) simulation, the experiment configuration was addressed, results from which show good similarity between the outcomes from the simulations and those from the experiments. Wavelet transform was further used to process the acquired Lamb wave signals for the purpose of damage detection and localization. Meanwhile, the velocity of the Lamb waves was calculated, illustrating that the fundamental anti-symmetric (A0) Lamb wave mode was excited in this case. The results demonstrate that Lamb waves can also be applied to some thick structures for the purpose of structural health monitoring.

Role of transducer inertia in generation, sensing, and time-reversal process of Lamb waves in thin plates with surface-bonded piezoelectric transducers

2021 ◽  
pp. 1045389X2110290
Author(s):  
Santosh Kapuria ◽  
Bhabagrahi Natha Sharma ◽  
A Arockiarajan
Keyword(s):  
Lamb Wave ◽  
Lamb Waves ◽  
Closed Form Solution ◽  
Form Solution ◽  
Thin Plates ◽  
Bonding Layer ◽  
Shear Lag ◽  
Time Reversibility ◽  
Plate Interface ◽  
Inertia Effects

An analytical model is presented for the generation, sensing, and time-reversible process of Lamb waves in thin isotropic plates with surface-bonded piezoelectric wafer transducers, incorporating the shear-lag effect of the bonding layer and inertia effects of the system in transducer modeling. A one-dimensional dynamic shear-lag model for the actuator-plate interaction is used to obtain the shear stress distribution at the actuator-plate interface. The Lamb wave solution for the plate under this shear traction excitation is obtained using the two-dimensional (2D) elasticity equations. A consistent sensor-plate interaction model incorporating the shear-lag and inertia effects is developed to determine the induced sensor voltage from the Lamb strain at the plate surface. The model is validated by comparing it with the 2D coupled piezoelasticity-based finite element simulation and experimental data. Detailed parametric studies are conducted to illustrate the effect of inclusion of inertia of actuator, sensor, adhesive, and plate in the transducer modeling on the Lamb wave generation, sensing, time reversibility, and the system’s best reconstruction frequency, and to ascertain how various geometrical and material parameters of the system influence the same. The developed closed-form solution will be immensely useful for the design of Lamb wave based structural health monitoring systems.

A novel time–frequency transform for broadband Lamb waves dispersion characteristics analysis

2021 ◽  
pp. 147592172097928
Author(s):  
Zhi Luo ◽  
Liang Zeng ◽  
Jing Lin
Keyword(s):  
High Resolution ◽  
Lamb Wave ◽  
Lamb Waves ◽  
Dispersion Compensation ◽  
Wave Mode ◽  
Linear Mapping ◽  
Mapping Technique ◽  
Dispersion Characteristics ◽  
Frequency Compensation ◽  
Time Frequency

Owing to carrying rich information about structure flaws, broadband Lamb waves are considered as a promising tool for non-destructive testing. However, since every Lamb wave mode has its own dispersion characteristics, the feature extraction among broadband multimodal Lamb wave is challenging. Time–frequency representation is significantly effective to analyze dispersive signals. In this article, taking advantages of the idea of dispersion compensation, two kinds of time–frequency domain dispersion analysis methods for broadband Lamb wave were proposed. The first one is based on the concept of the general parameterized time–frequency transform. A kernel function related to group delay was designed and the time–frequency compensation transform was proposed. The other one combines the segment linear mapping technique and the short-frequency Fourier transform, called the time–frequency de-dispersion transform. Both these two methods work well in representing multimodal Lamb wave signals with high resolution. However, time–frequency de-dispersion transform outperforms in representing multipath Lamb waves than time–frequency compensation transform. Moreover, a mode purification strategy was also proposed for distinguishing the interested mode from interferences. According to verification in synthetic and experimental data, not only the multimodal components but also multipath echoes are represented in time–frequency plane with high resolution. Finally, the proposed method shows a great robustness to inaccuracies in the dispersion data.

Finite Element Simulation of Damage Detection of Stiffened Plate under Temperature Variation

2011 ◽  
Vol 230-232 ◽  
pp. 75-79
Author(s):  
Wen Zhong Qu ◽  
Li Xiao
Keyword(s):  
Finite Element ◽  
Damage Detection ◽  
Finite Element Simulation ◽  
Lamb Wave ◽  
Elevated Temperatures ◽  
Lamb Waves ◽  
Thin Plates ◽  
Diagnostic Tools ◽  
Stiffened Plate ◽  
Element Simulation

Lamb waves are ultrasonic elastic waves that travel inside and along thin plates and is frequently used as diagnostic tools to detect damage in plate-like structures. In this paper, a transient dynamic finite element simulation of Lamb wave with piezoelectric transducers for damage detection in a stiffened plate under different temperature condition is carried out on the commercial finite element code ANSYS platform. Simulations are conducted over a temperature range. The changes in temperature-dependent material properties are used to measure the differences in the response signal’s waveform. The baseline selection method and baseline signal stretch method are used to compensate the temperature influence on Lamb wave propagation. The results of the numerical simulation demonstrate the effectiveness of the temperature compensation approach and the simulated damage on the stiffened plate can be defected effectively under elevated temperatures environment.

scholarly journals Theoretical and Experimental Investigation of Vehicle-Mounted Transient Electromagnetic Method Detection for Internal Defects of Operational Tunnels

2021 ◽  
Vol 11 (15) ◽  
pp. 6906
Author(s):  
Wangping Qian ◽  
Honghui Li ◽  
Jun Yu ◽  
Zhenyuan Gu
Keyword(s):  
Rapid Detection ◽  
High Speed ◽  
Surface Defects ◽  
Detection Method ◽  
Electromagnetic Method ◽  
Transient Electromagnetic Method ◽  
Internal Defects ◽  
Transient Electromagnetic ◽  
Detection Technology ◽  
Lining Structure

With the durable operation of high-speed railway tunnels in China, many tunnel defects successively appeared in the tunnel lining structure and gradually threatened the safe operation of the tunnels. In the limited maintenance time of high-speed railways, it is urgent to find out and maintain tunnel defects, especially internal defects. We propose an applied detection technology called the vehicle-mounted transient electromagnetic method (TEM). The detection technology aims to rapidly detect and locate the internal defects of the lining structure throughout the entire tunnel. Firstly, we investigate tunnel defects in detail and introduce the rapid detection method. Secondly, we analyze the principle and process of vehicle-mounted TEM. Thirdly, the rationality and applicability of vehicle-mounted TEM are verified by three different methods, including theoretical analysis, numerical simulation, and laboratory experiment. Finally, we compare the inversion results of experimental data under the two conditions. The results illustrate that tunnel surface defects are the external manifestations and characteristics of tunnel defects, while the forms of surface defects are directly related to internal defects. This detection method is suitable for the significant resistivity difference between tunnel defects and surrounding rocks, and its rationality is effectively validated. Furthermore, the apparent resistivity results reveal that there is a low resistivity region in front of the transmitter coil, and that the relative position can be preliminarily judged. The research results can provide a potential and significant application technology for the rapid detection of tunnel defects.

Research Situation Analysis of On-line Detection Technology for Power Transformer Winding Deformation

2020 ◽  
Vol 13 (6) ◽  
pp. 823-832
Author(s):  
Zhenhua Li ◽  
Weihui Jiang ◽  
Li Qiu ◽  
Zhenxing Li ◽  
Yanchun Xu
Keyword(s):  
Detection Method ◽  
Theoretical Research ◽  
Line Detection ◽  
Response Analysis ◽  
Advantages And Disadvantages ◽  
Detection Technology ◽  
The Future ◽  
Transformer Winding ◽  
On Line ◽  
Winding Deformation

Background: Winding deformation is one of the most common faults in power transformers, which seriously threatens the safe operation of transformers. In order to discover the hidden trouble of transformer in time, it is of great significance to actively carry out the research of transformer winding deformation detection technology. Methods: In this paper, several methods of winding deformation detection with on-line detection prospects are summarized. The principles and characteristics of each method are analyzed, and the advantages and disadvantages of each method as well as the future research directions are expounded. Finally, aiming at the existing problems, the development direction of detection method for winding deformation in the future is prospected. Results: The on-line frequency response analysis method is still immature, and the vibration detection method is still in the theoretical research stage. Conclusion: The ΔV − I1 locus method provides a new direction for on-line detection of transformer winding deformation faults, which has certain application prospects and practical engineering value.

scholarly journals A Two-Phase Fashion Apparel Detection Method Based on YOLOv4

2021 ◽  
Vol 11 (9) ◽  
pp. 3782
Author(s):  
Chu-Hui Lee ◽  
Chen-Wei Lin
Keyword(s):  
Object Detection ◽  
Transfer Learning ◽  
Detection Method ◽  
Phase Transfer ◽  
Recognition Task ◽  
Phase Detection ◽  
Target Domain ◽  
Two Phase ◽  
Detection Technology ◽  
Fashion Apparel

Object detection is one of the important technologies in the field of computer vision. In the area of fashion apparel, object detection technology has various applications, such as apparel recognition, apparel detection, fashion recommendation, and online search. The recognition task is difficult for a computer because fashion apparel images have different characteristics of clothing appearance and material. Currently, fast and accurate object detection is the most important goal in this field. In this study, we proposed a two-phase fashion apparel detection method named YOLOv4-TPD (YOLOv4 Two-Phase Detection), based on the YOLOv4 algorithm, to address this challenge. The target categories for model detection were divided into the jacket, top, pants, skirt, and bag. According to the definition of inductive transfer learning, the purpose was to transfer the knowledge from the source domain to the target domain that could improve the effect of tasks in the target domain. Therefore, we used the two-phase training method to implement the transfer learning. Finally, the experimental results showed that the mAP of our model was better than the original YOLOv4 model through the two-phase transfer learning. The proposed model has multiple potential applications, such as an automatic labeling system, style retrieval, and similarity detection.

A simple rapid detection method of DNA based on ligation-mediated real-time fluorescence PCR

The Analyst ◽  
2013 ◽  
Vol 138 (19) ◽  
pp. 5745 ◽  
Author(s):  
Yu Qing Du ◽  
Peng Fei Gao ◽  
Wei Wang ◽  
Ting Ting Wang ◽  
Yong Chang ◽  
...  
Keyword(s):  
Real Time ◽  
Rapid Detection ◽  
Detection Method
Sign in / Sign up

Export Citation Format

Share Document