Damage imaging using Lamb waves for SHM applications

2015 ◽  
Author(s):  
Tadeusz Stepinski ◽  
Łukasz Ambroziński ◽  
Tadeusz Uhl
Keyword(s):  
Lamb Waves ◽  
Damage Imaging

scholarly journals Damage Identification of Large Generator Stator Insulation Based on PZT Sensor Systems and Hybrid Features of Lamb Waves

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2745 ◽  
Author(s):  
Ruihua Li ◽  
Hao Li ◽  
Bo Hu
Keyword(s):  
Power Systems ◽  
Lamb Wave ◽  
Damage Identification ◽  
Lamb Waves ◽  
Fem Simulation ◽  
Correlation Coefficients ◽  
Hybrid Features ◽  
Material Inhomogeneity ◽  
Time Frequency ◽  
Damage Imaging

Large generators are the principal pieces of equipment in power systems, and their operation reliability critically depends on the stator insulation. Damages in stator insulation will gradually lead to the failure and breakdown of generator. Due to the advantages of Lamb waves in Structural health monitoring (SHM), in this study, a distributed piezoelectric (PZT) sensor system and hybrid features of the Lamb waves are introduced to identify stator insulation damage of large generator. A hierarchical probability damage-imaging (PDI) algorithm is proposed to tackle the material inhomogeneity and anisotropy of the stator insulation. The proposed method includes three steps: global detection using correlation coefficients, local detection using Time of flight (ToF) along with the amplitude of damage-scattered Lamb wave, and final images fusion. Wavelet Transform was used to extract the ToF of Lamb wave in terms of the time-frequency domain. Finite Element Modeling (FEM) simulation and experimental work were carried out to identify four typical stator insulation damages for validation, including inner void, inner delamination, puncture, and crack. Results show that the proposed method can precisely identify the location of stator insulation damage, and the reconstruction image can be used to identify the size of stator insulation damage.

A Method of Dispersion Compensation Based on Warped Frequency Transform

2013 ◽  
Vol 718-720 ◽  
pp. 2062-2067 ◽  
Author(s):  
Shang Chen Fu ◽  
Zhen Jian Lv ◽  
Ding Ma ◽  
Li Hua Shi
Keyword(s):  
High Resolution ◽  
Velocity Dispersion ◽  
Lamb Waves ◽  
Group Velocity Dispersion ◽  
Dispersion Compensation ◽  
Imaging Method ◽  
Finite Element Software ◽  
Damage Imaging ◽  
Resolution Imaging ◽  
Multi Mode

The use of Lamb waves for structural health monitoring (SHM) has complicated by its multi-mode character and dispersion effect, which impacts the damage positioning and high-resolution imaging. The group velocity dispersion curves of Lamb waves can be employed to warp the frequency axis, and then to establish warped frequency transform (WFT) to process Lamb waves. In this paper, received signals are directly compensated with warped frequency transform to suppress dispersion, and a new imaging method is proposed based on warped frequency transform. The propagation of Lamb waves in damaged aluminum plate is simulated by finite element software ABAQUS, results show that warped frequency transform can effectively compensate dispersive wave-packets, and high-resolution damage imaging can be obtained by the proposed method.

Least-squares reverse time migration (LSRTM) for damage imaging using Lamb waves

2019 ◽  
Vol 28 (6) ◽  
pp. 065010 ◽  
Author(s):  
Jiaze He ◽  
Daniel C Rocha ◽  
Patrick E Leser ◽  
Paul Sava ◽  
William P Leser
Keyword(s):  
Least Squares ◽  
Lamb Waves ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
Time Migration ◽  
Damage Imaging

A time reversal damage imaging method for structure health monitoring using Lamb waves

2010 ◽  
Vol 19 (11) ◽  
pp. 114301 ◽  
Author(s):  
Hai-Yan Zhang ◽  
Ya-Ping Cao ◽  
Xiu-Li Sun ◽  
Xian-Hua Chen ◽  
Jian-Bo Yu
Keyword(s):  
Health Monitoring ◽  
Time Reversal ◽  
Lamb Waves ◽  
Imaging Method ◽  
Structure Health Monitoring ◽  
Damage Imaging

Damage imaging that exploits multipath scattered Lamb waves

2019 ◽  
Vol 19 (6) ◽  
pp. 1629-1644 ◽  
Author(s):  
Liang Zeng ◽  
Liping Huang ◽  
Zhi Luo ◽  
Jing Lin
Keyword(s):  
Lamb Waves ◽  
Propagation Path ◽  
Imaging Method ◽  
Reinforced Polymer ◽  
Direct Scattering ◽  
Gaussian Distribution Function ◽  
Individual Wave ◽  
Damage Imaging ◽  
Wave Imaging ◽  
Polymer Laminates

This article presents a multipath Lamb wave imaging method that leverages the extra reflections present in the recorded ultrasonic waveforms for structural prognosis. Under the ray acoustic approximation, an edge behaves like a mirror, which changes the propagation path of a wave and provides more views of the damage than can be obtained from direct scattering. To accommodate for these extra reflections, the scattering path of each wave in the residual signal is simplified as a direct scattering path from an actual or virtual transmitter (created by edge mirroring) to the damage, and then back to an actual or virtual receiver (created by edge mirroring). On this basis, the Gaussian distribution function is introduced to quantify the probabilities at each spatial node in relation to all possible damage loci. Through fusing the images obtained from all individual wave packets, the structure could be inspected with far fewer transducers compared to conventional elliptical imaging. Experimental results from carbon fiber-reinforced polymer laminates and aluminum plate are provided to illustrate the effectiveness of the imaging method, where damage is correctly detected and accurately localized even with a single transmitter–receiver pair.

scholarly journals Structural damage imaging based on time-reversal theory for focusing of Lamb waves

2010 ◽  
Vol 59 (10) ◽  
pp. 7111
Author(s):  
Zhang Hai-Yan ◽  
Sun Xiu-Li ◽  
Cao Ya-Ping ◽  
Chen Xian-Hua ◽  
Yu Jian-Bo
Keyword(s):  
Time Reversal ◽  
Structural Damage ◽  
Lamb Waves ◽  
Reversal Theory ◽  
Damage Imaging
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