Damage identification in plate-like structures based on Lamb waves mode-conversion sensing using 3D laser vibrometer

This paper aims to develop a method to identify the damage location in circumference direction of a pipe using mode transformation of longitudinal guided wave. The corrosion-like damage in bimetal pipe is considered. Case study that damage detection for a bimetal pipe is used to show the validity and advantage of the proposed method. It can be found that the axially symmetric mode guided wave encounter the damage and the three modes were received in reflection. The damage location in circumferential directions could be identified by conversed modes measured at one position. The simulation shows a good performance.

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

Sensors ◽

10.3390/s18092745 ◽

2018 ◽

Vol 18 (9) ◽

pp. 2745 ◽

Cited By ~ 6

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.

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EXCITATION OF LAMB WAVES BY MODE CONVERSION ON A PERIODIC FLUID/SOLID PLATE INTERFACE

Ultrasonics International 87 ◽

10.1016/b978-0-408-02348-1.50077-9 ◽

1987 ◽

pp. 452-457

Author(s):

A. Jungman ◽

G. Quentin

Keyword(s):

Lamb Waves ◽

Mode Conversion ◽

Plate Interface ◽

Solid Plate

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A baseline-free approach of locating defect based on mode conversion and the reciprocity principle of Lamb waves

Ultrasonics ◽

10.1016/j.ultras.2020.106063 ◽

2020 ◽

Vol 102 ◽

pp. 106063

Author(s):

Hongbo Jia ◽

Hongwei Liu ◽

Zhichun Zhang ◽

Fuhong Dai ◽

Yanju Liu ◽

...

Keyword(s):

Lamb Waves ◽

Mode Conversion ◽

Reciprocity Principle

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Experimental Study on the Mode Conversion of Lamb Waves in a Metal Plate of Stepped Thickness Using Optical Detection

International Journal of the Society of Materials Engineering for Resources ◽

10.5188/ijsmer.17.201 ◽

2010 ◽

Vol 17 (2) ◽

pp. 201-204 ◽

Cited By ~ 6

Author(s):

Kazuhiko IMANO

Keyword(s):

Experimental Study ◽

Lamb Waves ◽

Mode Conversion ◽

Optical Detection ◽

Metal Plate

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Damage Identification by Embedded Piezoceramic Sensors in the Composite Plate

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.326-328.1697 ◽

2006 ◽

Vol 326-328 ◽

pp. 1697-1700

Author(s):

Heoung Jae Chun ◽

Choong Hee Yi ◽

Joon Hyung Byun

Keyword(s):

Monitoring System ◽

Health Monitoring ◽

Composite Laminates ◽

Damage Identification ◽

Lamb Waves ◽

Structural Systems ◽

Detection Accuracy ◽

Health Monitoring System ◽

Localized Defects ◽

The Many

The embedded structural health monitoring system is envisioned to be an important factor of future structural systems. One of the many attractions of in situ health monitoring system is its capability to inspect the structural systems in less intrusive way over many other visual inspections which require disassembly of built up structures when some indications have appeared that damages have occurred in the structural systems The vacuum assisted resin transfer molding (VARTM) process is used to fabricate woven-glass/phenol composite specimens which have the PZT sensor array embedded in them. The embedded piezoceramic (PZT) sensors are used as both transmitters and receivers. A damage identification approach is developed for a woven-glass/phenol composite laminates with known localized defects. Propagation of the Lamb waves in laminates and their interactions with the defects are examined. Lamb waves are generated by the high power ultrasonic analyzer. A real time active diagnosis system is therefore established. The results obtained show that satisfactory detection accuracy could be achieved by proposed method.

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Defects Detection and Localization in Underwater Plates Using Laser Laterally Generated Pure Non-Dispersive S0 Mode

Applied Sciences ◽

10.3390/app9030459 ◽

2019 ◽

Vol 9 (3) ◽

pp. 459 ◽

Cited By ~ 2

Author(s):

Qingnan Xie ◽

Chenyin Ni ◽

Zhonghua Shen

Keyword(s):

Defect Detection ◽

Lamb Waves ◽

Mode Conversion ◽

High Sensitivity ◽

Laser Source ◽

Dispersion Characteristics ◽

High Attenuation ◽

Corrosion Defects ◽

Detection And Localization ◽

Lateral Excitation

When working in humid environments, corrosion defects are easily produced in metallic plates. For defect detection in underwater plates, symmetric modes of Lamb waves are widely used because of their characteristics including long propagating distance and high sensitivity to defects. In this study, we extend our previous work by applying the laser laterally generated S0 mode to detection and localization of defects represented by artificial notches in an aluminum plate immersed in water. Pure non-dispersive S0 mode is generated in an underwater plate by lateral laser source irradiation and its fd (frequency·thickness) range is selected by theoretical calculation. Using this lateral excitation, the S0 mode is enhanced; meanwhile, the A0 mode is effectively suppressed. The mode-converted A0 mode from the incident S0 mode is used to detect and localize the defect. The results reveal a significantly improved capability to detect defects in an underwater plate using the laser laterally generated S0 mode, while that using A0 is limited due to its high attenuation. Furthermore, owing to the long propagating distance and the non-dispersion characteristics of the S0 generated by the lateral laser source, multiple defects can also be detected and localized according to the mode conversion at the defects.

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