Time reversibility of Lamb waves in thin plates with surface-bonded piezoelectric transducers is temperature invariant at the best reconstruction frequency

2020 ◽  
pp. 147592172096512
Author(s):  
Bhabagrahi Natha Sharma ◽  
Santosh Kapuria ◽  
A Arockiarajan
Keyword(s):  
Temperature Dependence ◽  
Lamb Wave ◽  
Lamb Waves ◽  
Dominant Role ◽  
Excitation Frequency ◽  
Piezoelectric Transducers ◽  
Time Reversibility ◽  
Adhesive Layers ◽  
Wide Range ◽  
Reconstructed Signal

The Lamb wave time-reversal method has been widely proposed as a baseline-free method for damage detection in thin-walled structures. Under varying thermal environments, it would require that the time reversibility of Lamb waves is temperature invariant. In this study, we examine the temperature dependence of Lamb waves and its time reversibility using experiments and finite element simulations on isotropic plates with surface-bonded piezoelectric wafer transducers for actuation and sensing. The study is conducted at three different temperatures of the system from 25°C to 75°C for a wide range of excitation frequency. The results indicate that the time reversibility can undergo significant changes due to temperature variations depending on the excitation frequency. However, at the best reconstruction frequency corresponding to the maximum similarity of the reconstructed signal with the original input signal (proposed recently as the probing frequency), the change in the percent similarity with temperature is insignificant. The results also demonstrate that changes in the physical properties of both adhesive layers and piezoelectric transducers with temperature play a dominant role in influencing Lamb wave amplitudes. However, only the change in the characteristics of the adhesive layers is responsible for the temperature dependence of the time reversibility of Lamb waves.

Parametric Models of Ultrasonic Piezoelectric Transducers over a Wide Temperature Range

2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 000266-000272 ◽  
Author(s):  
Steven A. Morris ◽  
Jeremy Townsend
Keyword(s):  
Dielectric Constant ◽  
Temperature Dependence ◽  
Coupling Coefficient ◽  
Thin Disk ◽  
Piezoelectric Transducers ◽  
Parametric Models ◽  
Model Parameters ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
Wide Range

Piezoelectric ultrasonic transducers are used extensively in well logging and logging-while-drilling applications for pulse-echo operation. We present a method of modeling the operation of ultrasonic thin-disk piezoelectric transducers over a wide range of temperatures. The model is based on using Redwood's version of Mason's model of thin-disk transducers. Laboratory measurements in the oven of non-backed transducers in air are used to extract the Mason model parameters as a function of temperature. Derived parameters are frequency-thickness constant, dielectric constant, and thickness mode coupling coefficient. A fourth parameter, bulk density, is measured independently and assumed constant over temperature. Temperature dependence of frequency thickness constant and coupling coefficient are modeled as linear temperature coefficients. Temperature dependence of the dielectric constant must be specified as a table because of the non-linear temperature dependence of that parameter.

scholarly journals An Efficient Time Reversal Method for Lamb Wave-Based Baseline-Free Damage Detection in Composite Laminates

2018 ◽  
Vol 9 (1) ◽  
pp. 11 ◽  
Author(s):  
Liping Huang ◽  
Junmin Du ◽  
Feiyu Chen ◽  
Liang Zeng
Keyword(s):  
Damage Detection ◽  
Time Reversal ◽  
Lamb Wave ◽  
Composite Laminates ◽  
Narrow Band ◽  
Great Influence ◽  
Time Intervals ◽  
Wide Range ◽  
Reconstructed Signal ◽  
Short Time

Time reversal (TR) concept is widely used for Lamb wave-based damage detection. However, the time reversal process (TRP) faces the challenge that it requires two actuating-sensing steps and requires the extraction of re-emitted and reconstructed waveforms. In this study, the effects of the two extracted components on the performance of TRP are studied experimentally. The results show that the two time intervals, in which the waveforms are extracted, have great influence on the accuracy of damage detection of the time reversal method (TRM). What is more, it requires a large number of experiments to determine these two time intervals. Therefore, this paper proposed an efficient time reversal method (ETRM). Firstly, a broadband excitation is applied to obtain response at a wide range of frequencies, and ridge reconstruction based on inverse short-time Fourier transform is applied to extract desired mode components from the broadband response. Subsequently, deconvolution is used to extract narrow-band reconstructed signal. In this method, the reconstructed signal can be easily obtained without determining the two time intervals. Besides, the reconstructed signals related to a series of different excitations could be obtained through only one actuating-sensing step. Finally, the effectiveness of the ETRM for damage detection in composite laminates is verified through experiments.

Laser Induced Lamb Wave Generation for Structural Health Monitoring of Carbon Fiber Reinforced Polymers

2015 ◽  
Author(s):  
Ron Sebastian ◽  
Benjamin Kelkel ◽  
Martin Gurka ◽  
Tobias Traub ◽  
Johannes L’huillier
Keyword(s):  
Carbon Fiber ◽  
Health Monitoring ◽  
Lamb Wave ◽  
Acoustic Waves ◽  
Lamb Waves ◽  
Piezoelectric Transducers ◽  
Signal Generation ◽  
Fiber Reinforced Polymers ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers

In this paper we present an innovative concept for the excitation of guided acoustic waves (lamb waves) in carbon fiber reinforced polymers (CFRP). The idea is to add this external signal generation to a passive structural health monitoring system (SHM), using the now active system for nondestructive testing (NDT). The whole system consists of piezoelectric sensors, embedded in the polymer matrix of the monitored component, the external laser in combination with a scanning device for spatial resolved generation of acoustic waves and a signal processing unit for data analysis. Using laser excitation for lamb wave generation helps to overcome several dis-advantages compared to the use of piezoelectric transducers only: The flexibility in repositioning of the excitation area allows for easy compensation of the strong signal attenuation of CFRP with a minimum number of piezoelectric transducers. The variation of laser wavelength in the range of 1024 to 3500 nm in combination with variation in intensity allows for a selective coupling of the acoustic waves either into the matrix or in the C fibers. Using piezoelectric transducers for detection only, omits the need for a large number of high-voltage amplifiers for signal generation. In this contribution we present first results of a systematic investigation of the effective generation of lamb waves in CFRP. In addition to the variation of the wavelength of the laser, the intensity was varied too. A potentially damaging influence of the laser radiation on the CFRP material was investigated.

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 Wave Frequency Effects on Damage Imaging in Adhesive Joints Using Lamb Waves and RMS

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1842 ◽  
Author(s):  
Erwin Wojtczak ◽  
Magdalena Rucka
Keyword(s):  
Damage Identification ◽  
Lamb Waves ◽  
Excitation Frequency ◽  
Visual Assessment ◽  
Adhesive Joints ◽  
Ultrasonic Waves ◽  
Steel Plates ◽  
Wave Frequency ◽  
Destructive Testing ◽  
Wide Range

Structural adhesive joints have numerous applications in many fields of industry. The gradual deterioration of adhesive material over time causes a possibility of unexpected failure and the need for non-destructive testing of existing joints. The Lamb wave propagation method is one of the most promising techniques for the damage identification of such connections. The aim of this study was experimental and numerical research on the effects of the wave frequency on damage identification in a single-lap adhesive joint of steel plates. The ultrasonic waves were excited at one point of an analyzed specimen and then measured in a certain area of the joint. The recorded wave velocity signals were processed by the way of a root mean square (RMS) calculation, giving the actual position and geometry of defects. In addition to the visual assessment of damage maps, a statistical analysis was conducted. The influence of an excitation frequency value on the obtained visualizations was considered experimentally and numerically in the wide range for a single defect. Supplementary finite element method (FEM) calculations were performed for three additional damage variants. The results revealed some limitations of the proposed method. The main conclusion was that the effectiveness of measurements strongly depends on the chosen wave frequency value.

Structural Health Monitoring of Plate Structures Using Lamb Wave Methods

2011 ◽  
Vol 368-373 ◽  
pp. 2417-2420
Author(s):  
Nai Zhi Zhao ◽  
Chang Tie Huang ◽  
Xin Chen
Keyword(s):  
Lamb Wave ◽  
Lamb Waves ◽  
Experimental Testing ◽  
Excitation Frequency ◽  
Diagnostic Technique ◽  
Frequency Dispersion ◽  
Dispersion Curves ◽  
Test Configuration ◽  
Wave Measurements ◽  
Test Variability

In this paper，waveform is used to excite Lamb waves in the test plates during experimental testing. The optimal excitation frequency will depend on the test configuration. In order to select an excitation frequency, dispersion curves are first created to show what frequency range is best suited for Lamb wave excitation. According to dispersion curves were created for the aluminum test plates and it was concluded that a frequency below 1 MHz will be used in order to only excite the fundamental and modes. Experiments are performed on the aluminum test plates described. Experimental testing is first performed on undamaged plates in order to determine the path-to-path and test-to-test variability in Lamb wave measurements in the absence of damage. The admittance data is analyzed in order to determine if any of the PZT transducers need to be replaced because of poor bonding or mechanical failure. The sensor diagnostic technique is applied to each plate and used to ensure proper consistency between PZT transducers

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.

Effect of structural damping on the tuning between piezoelectric wafer active sensors and Lamb waves

2018 ◽  
Vol 29 (10) ◽  
pp. 2177-2191 ◽  
Author(s):  
Hanfei Mei ◽  
Victor Giurgiutiu
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Lamb Wave ◽  
Lamb Waves ◽  
Excitation Frequency ◽  
Structural Damping ◽  
Active Sensors ◽  
Piezoelectric Wafer Active Sensors ◽  
Active Sensor ◽  
Piezoelectric Wafer

Piezoelectric wafer active sensors have been widely used for Lamb-wave generation and acquisition. For selective preferential excitation of a certain Lamb-wave mode and rejection of other modes, the piezoelectric wafer active sensor size and the excitation frequency should be tuned. However, structural damping depends on the structure material and the excitation frequency and it will affect the amplitude response of piezoelectric wafer active sensor–excited Lamb waves in the structure, that is, tuning curves. Its influence on the piezoelectric wafer active sensor tuning reflects the effect of structural health monitoring configuration considered in the excitation. Therefore, it is important to have knowledge about the effect of structural damping on the tuning between piezoelectric wafer active sensor and Lamb waves. In this article, the analytical tuning solution of undamped media is extended to damped materials using the Kelvin–Voigt damping model, in which a complex Young’s modulus is utilized to include the effect of structural damping as an improvement over existing models. This extension is particularly relevant for the structural health monitoring applications on high-loss materials, such as metallic materials with viscoelastic coatings and fiber-reinforced polymer composites. The effects of structural damping on the piezoelectric wafer active sensor tuning are successfully captured by the improved model, with experimental validations on an aluminum plate with adhesive films on both sides and a quasi-isotropic woven composite plate using circular piezoelectric wafer active sensor transducers.

scholarly journals Lamb Wave-Based Damage Localization Feature Enhancement and Extraction Method for Stator Insulation of Large Generators Using VMD and Wavelet Transform

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4205
Author(s):  
Ruihua Li ◽  
Jing Luo ◽  
Bo Hu
Keyword(s):  
Wavelet Transform ◽  
Lamb Wave ◽  
Background Noise ◽  
Lamb Waves ◽  
Signal To Noise Ratio ◽  
Scattered Wave ◽  
Damage Location ◽  
Wave Detection ◽  
Mode Decomposition ◽  
Reconstructed Signal

Lamb waves are used to locate any damage in the stator insulation structure of large generators. However, it is difficult to extract the features of Lamb wave signals in a strong background noise environment, thus significantly reducing the accuracy with which the damage is located. This paper proposes a method based on variational mode decomposition (VMD) and wavelet transform to enhance and extract the location features of stator insulation damage signals of large motors. First, considering that the characteristics of VMD are sensitive to noise, the Lamb wave detection signal is decomposed, denoised, and reconstructed; the reconstructed signal is then wavelet-transformed to extract the time of flight (TOF) of the damage-scattered wave as the damage location feature; finally, the damage location is determined using the TOF features. The proposed method is experimentally tested and verified under various noise environments. The results show that the VMD and wavelet transform methods can significantly improve the signal-to-noise ratio of Lamb wave detection signals and the accuracy with which the damage is located under strong background noise. This study extends the applicability of Lamb wave-based non-destructive detection of stator insulation damage in complex environments.

Effect of Lamb Wave Excitation Frequency on Detection of Delamination in Composite Plates

2011 ◽  
Author(s):  
Inho Kim ◽  
Ratneshwar Jha
Keyword(s):  
Lamb Wave ◽  
Lamb Waves ◽  
Excitation Frequency ◽  
Damage Index ◽  
Laser Doppler Vibrometer ◽  
Composite Plates ◽  
Experimental Investigations ◽  
Wave Excitation ◽  
Error Norm ◽  
Hilbert Huang Transform

This paper presents experimental investigations of the effect of Lamb wave excitation frequency on detection of a given delamination in composite plates. Typical aerospace type composite plates are used and integrated piezoelectric transducers function as both actuator and sensor. Also, a scanning Laser Doppler Vibrometer (LDV) is used for preliminary sensing of structural responses when excited by a single PZT actuator. Results in time domain are quantified by a damage index calculation based on modified L2 error norm. Phase difference calculations based on complex continuous wavelet transform (CWT) and Hilbert-Huang transform (HHT) are presented. Experimental results show a significant effect of incident Lamb waves on delamination signature.

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