Excitation of Guided Waves in Oil Storage Tank Floor and Vertical Wall by Edge- and Wall-Mounted Transducers

2010 ◽  
Author(s):  
Weibin Wang ◽  
Zhanjun Feng ◽  
Choumin Zhao ◽  
Keyi Yuan ◽  
Zandong Han ◽  
...  
Keyword(s):  
Longitudinal Wave ◽  
Lamb Wave ◽  
Pulse Train ◽  
Guided Waves ◽  
Lamb Waves ◽  
Vertical Wall ◽  
Low Frequency ◽  
Longitudinal Waves ◽  
Oil Storage ◽  
Wave Modes

Oil storage tanks are crucial components in the petrochemical industry for transportation and storage. Corrosion of the tank floor and vertical walls is one of the most important safety concerns. In-situ inspection of the tank floor and walls with ultrasonic guided wave technique by edge- and wall-mounted transducers is still an active research area nowadays. A great deal of research has been conducted in detecting the defect of plate-like structures using Lamb waves. This application has been motivated by the fact that the Lamb wave velocity is the function of frequency and structural geometry (thickness), also the Lamb waves can propagate with low attenuation for long distance in plate structure. However, the complexity due to the existence of multiple Lamb wave modes weakens its applicability. Lamb waves are typically excited by transducers mounted on the surface of the inspected plates. Higher order modes are generated if the frequency-thickness product exceeds a certain threshold value that is dependent on the material of the plates. Low frequency guided waves can reduce this complication as only a small number of wave modes are generated. So operation with low frequency guided waves is usually recommended, but it encounters a problem that the resolution gets degraded hence small defects (compared to the wavelength) are difficult to detect. Our investigation considers the generation of guided waves in tank floor and vertical wall by edge excitation and wall-mounted excitation, respectively. Only when there is no access to the edge of the vertical wall, the wall-mounted excitation (surface excitation) is used. When the frequency-thickness product is small Lamb waves are generated, otherwise, longitudinal waves are generated. We investigate the intermediate frequency-thickness products where a pulse train of semi-longitudinal waves is excited. The pulse train is comprised of a leading pulse and some railing pulses, which have been predicted by the acoustic theory. The transition from Lamb wave to semi-longitudinal wave is investigated. In addition, energy transport from leading pulse to trailing pulses and the interaction of these trailing pulses with defects are studied. The results revealed that the semi-longitudinal wave is a viable option for tank floor and wall defect inspection.

scholarly journals The numerical analysis of the interaction between the low-order Lamb wave modes and surface breaking cracks

2019 ◽  
Vol 254 ◽  
pp. 08001 ◽  
Author(s):  
Michal Šofer ◽  
Petr Ferfecki ◽  
Martin Fusek ◽  
Pavel Šofer ◽  
Renata Gnatowska
Keyword(s):  
Lamb Wave ◽  
Guided Waves ◽  
Lamb Waves ◽  
Numerical Study ◽  
Large Structures ◽  
Piping Systems ◽  
Geometric Discontinuities ◽  
Surface Breaking Crack ◽  
Wave Modes ◽  
Low Order

Lamb waves, as one of the types of guided waves, are extensively used for inspecting large structures as well as for structure health monitoring applications. One of the biggest benefits of guided waves is their ability to travel over long distances without much attenuation. Lamb waves are often used for inspection of piping systems and similar geometries where the dimension in the third direction is significantly smaller than the other two. No wonder that the study of the interaction of Lamb waves with particular types of geometric discontinuities is a frequent topic of research. The main aim of the proposed paper is to present the findings related to the numerical study of the interaction between low-order Lamb wave modes and surface breaking crack oriented at different angles relative to the free surface.

Inspection of Concrete-Metal Rod Interface Using Guided Waves

2000 ◽  
Author(s):  
Won-Bae Na ◽  
Tribikram Kundu ◽  
Mohammad R. Ehsani
Keyword(s):  
Lamb Wave ◽  
Guided Waves ◽  
Lamb Waves ◽  
Guided Wave ◽  
Ultrasonic Transducers ◽  
Interface Debonding ◽  
Long Distance ◽  
Steel Rebar ◽  
Steel Bars ◽  
Steel Rebars

Abstract The feasibility of detecting interface degradation and separation of steel rebars in concrete beams using Lamb waves is investigated in this paper. It is shown that Lamb waves can easily detect these defects. A special coupler between the steel rebar and ultrasonic transducers has been used to launch non-axisymmetric guided waves in the steel rebar. This investigation shows that the Lamb wave inspection technique is an efficient and effective tool for health monitoring of reinforced concrete structures because the Lamb wave can propagate a long distance along the reinforcing steel bars embedded in concrete as the guided wave and is sensitive to the interface debonding between the steel rebar and concrete.

Contribution of Lamb wave modes in the formation of higher order modes cluster (HOMC) guided waves

2021 ◽  
pp. 095440622110424
Author(s):  
Z Abbasi ◽  
F Honarvar
Keyword(s):  
Finite Element ◽  
Wave Packet ◽  
Lamb Wave ◽  
Guided Waves ◽  
Element Model ◽  
Higher Order ◽  
Guided Wave ◽  
Cross Sectional ◽  
Higher Order Modes ◽  
Wave Modes

In recent years, Higher Order Modes Cluster (HOMC) guided waves have been considered for ultrasonic testing of plates and pipes. HOMC guided waves consist of higher order Lamb wave modes that travel together as a single nondispersive wave packet. The objective of this paper is to investigate the effect of frequency-thickness value on the contribution of Lamb wave modes in an HOMC guided wave. This is an important issue that has not been thoroughly investigated before. The contribution of each Lamb wave mode in an HOMC guided wave is studied by using a two-dimensional finite element model. The level of contribution of various Lamb wave modes to the wave cluster is verified by using a 2D FFT analysis. The results show that by increasing the frequency-thickness value, the order of contributing modes in the HOMC wave packet increases. The number of modes that comprise a cluster also increases up to a specific frequency-thickness value and then it starts to decrease. Plotting of the cross-sectional displacement patterns along the HOMC guided wave paths confirms the shifting of dominant modes from lower to higher order modes with increase of frequency-thickness value. Experimental measurements conducted on a mild steel plate are used to verify the finite element simulations. The experimental results are found to be in good agreement with simulations and confirm the changes observed in the level of contribution of Lamb wave modes in a wave cluster by changing the frequency-thickness value.

Determination of Vibration Source Locations in Laminated Composite Plates Using Lamb Wave Analysis

2010 ◽  
Vol 123-125 ◽  
pp. 899-902
Author(s):  
Chao Du ◽  
Qing Qing Ni ◽  
Toshiaki Natsuki
Keyword(s):  
Lamb Wave ◽  
Guided Waves ◽  
Lamb Waves ◽  
Laminated Composite ◽  
Composite Plates ◽  
Wave Dispersion ◽  
Laminated Plates ◽  
Vibration Source ◽  
Arrival Times ◽  
Wave Velocities

Signals propagate on plate-like structures as ultrasonic guided waves, and analysis of Lamb waves has been widely used for on-line monitoring. In this study, the wave velocities of symmetric and anti-symmetric modes in various directions of propagation were investigated. Since the wave velocities of these two modes are different, it is possible to compute the difference in their arrival times when these waves propagated the distance from the vibration source to sensor. This paper presents an evaluation formulation of wave velocity and describes a generalized algorithm for locating a vibration source on a thin, laminated plate. With the different velocities of two modes based on Lamb wave dispersion, the method uses two sensors to locate the source on a semi-infinite interval of a plate. The experimental procedure supporting this method employs pencil lead breaks to simulate vibration sources on quasi-isotropic and unidirectional laminated plates. The transient signals generated in this way are transformed using a wavelet transform. The vibration source locations are then detected by utilizing the distinct wave velocities and arrival times of the symmetric and anti-symmetric wave modes. The method is an effective technique for identifying impact locations on plate-like structures.

Lamb Wave Inspection of Concrete Beams

1999 ◽  
Author(s):  
Y. C. Jung ◽  
T. Kundu ◽  
M. Ehsani
Keyword(s):  
Lamb Wave ◽  
Concrete Beams ◽  
Lamb Waves ◽  
Time Of Flight ◽  
Signal Amplitude ◽  
Internal Defects ◽  
Longitudinal Waves ◽  
Ultrasonic Methods ◽  
Wave Technique ◽  
Flight Measurements

Abstract The feasibility of detecting defects in concrete beams using Lamb waves is investigated in this paper. The traditional ultrasonic methods for inspecting defects in concrete use the reflection and scattering of longitudinal waves by internal defects. Signal amplitude and time of flight measurements provide information about the internal defects in concrete. However, these methods are time consuming and often fail to detect honeycombs, closed cracks and small defects. In this paper the potential of the Lamb wave technique to detect those defects in large concrete beams is investigated. The Lamb wave technique is found to be reliable for detecting such defects in concrete beams.

scholarly journals Numerical Investigation of Excitation of Various Lamb Waves Modes in Thin Plastic Films

2022 ◽  
Vol 12 (2) ◽  
pp. 849
Author(s):  
Rymantas Jonas Kazys ◽  
Justina Sestoke ◽  
Egidijus Zukauskas
Keyword(s):  
Numerical Investigation ◽  
Lamb Wave ◽  
Guided Waves ◽  
Phased Array ◽  
Ultrasonic Transducer ◽  
Guided Wave ◽  
Ultrasonic Guided Waves ◽  
Plastic Films ◽  
Thin Plastic ◽  
Wave Modes

Ultrasonic-guided waves are widely used for the non-destructive testing and material characterization of plates and thin films. In the case of thin plastic polyvinyl chloride (PVC), films up to 3.2 MHz with only two Lamb wave modes, antisymmetrical A0 and symmetrical S0, may propagate. At frequencies lower that 240 kHz, the velocity of the A0 mode becomes slower than the ultrasonic velocity in air which makes excitation and reception of such mode complicated. For excitation of both modes, we propose instead a single air-coupled ultrasonic transducer to use linear air-coupled arrays, which can be electronically readjusted to optimally excite and receive the A0 and S0 guided wave modes. The objective of this article was the numerical investigation of feasibility to excite different types of ultrasonic-guided waves, such as S0 and A0 modes in thin plastic films with the same electronically readjusted linear phased array. Three-dimensional and two-dimensional simulations of A0 and S0 Lamb wave modes using a single ultrasonic transducer and a linear phased array were performed. The obtained results clearly demonstrate feasibility to excite efficiently different guided wave modes in thin plastic films with readjusted phased array.

scholarly journals Core–skin debonding detection in honeycomb sandwich structures through guided wave wavefield analysis

2018 ◽  
Vol 30 (9) ◽  
pp. 1306-1317 ◽  
Author(s):  
Lingyu Yu ◽  
Zhenhua Tian ◽  
Xiaopeng Li ◽  
Rui Zhu ◽  
Guoliang Huang
Keyword(s):  
Guided Waves ◽  
Sandwich Structures ◽  
Lamb Waves ◽  
Laser Doppler Vibrometer ◽  
Low Frequency ◽  
Guided Wave ◽  
Honeycomb Sandwich ◽  
Debonding Detection ◽  
The Waves ◽  
Detection And Quantification

Ultrasonic guided waves have proven to be an effective and efficient method for damage detection and quantification in various plate-like structures. In honeycomb sandwich structures, wave propagation and interaction with typical defects such as hidden debonding damage are complicated; hence, the detection of defects using guided waves remains a challenging problem. The work presented in this article investigates the interaction of low-frequency guided waves with core–skin debonding damage in aluminum core honeycomb sandwich structures using finite element simulations. Due to debonding damage, the waves propagating in the debonded skin panel change to fundamental antisymmetric Lamb waves with different wavenumber values. Exploiting this mechanism, experimental inspection using a non-contact laser Doppler vibrometer was performed to acquire wavefield data from pristine and debonded structures. The data were then processed and analyzed with two wavefield data–based imaging approaches, the filter reconstruction imaging and the spatial wavenumber imaging. Both approaches can clearly indicate the presence, location, and size of the debonding in the structures, thus proving to be effective methods for debonding detection and quantification for honeycomb sandwich structures.

Simulation of Lamb Wave Propagation Using Excitation Potentials

2017 ◽  
Author(s):  
Mohammad Faisal Haider ◽  
Victor Giurgiutiu ◽  
Bin Lin ◽  
Lingyu Yu
Keyword(s):  
Elastic Waves ◽  
Lamb Wave ◽  
Lamb Waves ◽  
Plate Thickness ◽  
Signal Amplitude ◽  
Pressure Potential ◽  
Theoretical Formulation ◽  
Damage Process ◽  
Plane Displacement ◽  
Wave Modes

Acoustic emission (AE) can be used to measure energy associated with inelastic deformation such as slip, twinning, and microcracking, etc. in a structure. By obtaining AE information during a damage process, the failure indication can be detected. Therefore, better understanding of AE from a damage process is essential for proper damage detection. Elastic waves emission from a damage process due to energy release can be generalized by excitation potentials. There are two types of potentials exists in a plate for straight crested Lamb waves: pressure potential and shear potential. Theoretical formulation showed that due to excitation potentials the elastic waves in a plate followed the Raleigh-Lamb wave equation. The total energy released from damage can be decomposed as pressure potential and shear potential. Each potential has contribution to different wave modes. A numerical simulation was conducted to identify different wave modes due to excitation potentials. Out of plane displacement was calculated numerically on top of the plate at 500 mm distance from excitation point in each of 2mm, 6mm and 12 mm thick stainless steel plate. There were large losses in peak signal amplitude of anti-symmetric fundamental mode (A0) with increasing plate thickness from 2mm to 12 mm.

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.

scholarly journals High-Frequency Guided Waves for Corrosion Thickness Loss Monitoring

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Daniel Chew ◽  
Bernard Masserey ◽  
Paul Fromme
Keyword(s):  
Wave Propagation ◽  
Wall Thickness ◽  
Lamb Wave ◽  
High Frequency ◽  
Guided Waves ◽  
Plate Thickness ◽  
Corrosion Damage ◽  
Element Model ◽  
Guided Wave ◽  
Wave Modes

Abstract Adverse environmental conditions result in corrosion during the life cycle of marine structures such as pipelines, offshore oil platforms, and ships. Generalized corrosion leading to the loss of wall thickness can cause the degradation of the integrity, strength, and load bearing capacity of the structure. Nondestructive detection and monitoring of corrosion damage in difficult to access areas can be achieved using high-frequency guided waves propagating along the structure. Using standard ultrasonic wedge transducers with single-sided access to the structure, specific high-frequency guided wave modes (overlap of both fundamental Lamb wave modes) were generated that penetrate through the complete thickness of the structure. The wave propagation and interference of the guided wave modes depend on the thickness of the structure and were measured using a noncontact laser interferometer. Numerical simulations using a two-dimensional finite element model were performed to visualize and predict the guided wave propagation and energy transfer across the plate thickness. During laboratory experiments, the wall thickness was reduced uniformly by milling of one steel plate specimen. In a second step, wall thickness reduction was induced using accelerated corrosion for two mild steel plates. The corrosion damage was monitored based on the effect on the wave propagation and interference (beating effect) of the Lamb wave modes in the frequency domain. Good agreement of the measured beatlengths with theoretical predictions was achieved, and the sensitivity of the methodology was ascertained, showing that high-frequency guided waves have the potential for corrosion damage monitoring at critical and difficult to access locations.

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