Lamb wave virtual time reversal damage detection algorithm with transducer transfer function compensation

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.

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A Time Reversal Imaging Method without Relying on Transfer Function for Impact and Damage Monitoring of Composite Structures

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.330.542 ◽

2013 ◽

Vol 330 ◽

pp. 542-548

Author(s):

Lei Qiu ◽

Shen Fang Yuan ◽

Tian Xiang Huang

Keyword(s):

Transfer Function ◽

Time Reversal ◽

Lamb Wave ◽

Composite Structures ◽

Structural Damage ◽

Composite Panel ◽

Synthesis Process ◽

Propagation Mechanism ◽

Imaging Method ◽

Phase Synthesis

Composite structures adopted in aerospace structures have attracted much interest to structural health monitoring (SHM) for localization of impact and damage positions due to their poor impact resistance properties. Propagation mechanism and frequency dispersion characteristics of Lamb wave signals on composite structures are more complicated than that on simple aluminum plates. Recently, much attention has been paid to the research of time reversal focusing method because this method shows a promising advantage to give a focusing image of the structural damage, improve the signal-to-noise ratio and compensate the dispersion of Lamb wave signals. In this paper, aiming at developing a practical method for on-line localization of impact and damage on aircraft composite structures which can take advantage of time reversal focusing and does not rely on the transfer function, a new phase synthesis based time reversal focusing method is proposed. Impact and damage images are given out directly through time reversal focusing based on phase synthesis process of the signals. A SHM demonstration system is built on a composite panel of an aircraft wing box with many bolt holes and stiffeners using the phase synthesis based time reversal focusing method. The demonstration results show that this method can estimate the positions of impact and damage efficiently with a low sensitivity of velocity errors.

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Lamb-Wave Based Damage Detection in Anisotropic Composite Plates

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.627.1 ◽

2014 ◽

Vol 627 ◽

pp. 1-4 ◽

Cited By ~ 10

Author(s):

Z. Sharif-Khodaei ◽

M.H. Aliabadi

Keyword(s):

Damage Detection ◽

Lamb Wave ◽

Lamb Waves ◽

Composite Plates ◽

Detection Algorithm ◽

Damage State ◽

Anisotropic Composite ◽

Cfrp Composite ◽

The Difference ◽

Imaging Algorithms

Damage detection in anisotropic composite plates based on Lamb wave technique has been investigated. A network of transducers is used to detect barely visible damage caused by impact. A CFRP composite plate has been impacted and tested to verify the proposed damage detection algorithms. The difference in the propagational properties of Lamb waves in the pristine state and the damage state is used through data fusion and imaging algorithms to detect, locate and characterise the damage. The influence of directionality of the velocity on the validity of the detection algorithm is examined and some results are presented.

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Numerical Investigation of Nonlinear Lamb Wave Time Reversing for Fatigue Crack Detection

Volume 9: Mechanics of Solids, Structures, and Fluids ◽

10.1115/imece2019-10881 ◽

2019 ◽

Author(s):

Junzhen Wang ◽

Yanfeng Shen

Keyword(s):

Finite Element ◽

Fatigue Crack ◽

Time Reversal ◽

Lamb Wave ◽

Crack Detection ◽

Guided Waves ◽

Fatigue Cracks ◽

Contact Dynamics ◽

Virtual Time ◽

Fatigue Crack Detection

Abstract This paper presents a numerical study on nonlinear Lamb wave time reversing for fatigue crack detection. An analytical framework is initially presented, modeling Lamb wave generation, propagation, wave crack linear and nonlinear interaction, and reception. Subsequently, a 3D transient dynamic coupled-field finite element model is constructed to simulate the pitch-catch procedure in an aluminum plate using the commercial finite element software (ANSYS). The excitation frequency is carefully selected, where only single Lamb wave mode will be generated by the Piezoelectric Wafer Active Sensor (PWAS). The fatigue cracks are modelled nucleating from both sides of a rivet hole. In addition, contact dynamics are considered to capture the nonlinear interactions between guided waves and the fatigue cracks, which would induce Contact Acoustic Nonlinearity (CAN) into the guided waves. Then the conventional and virtual time reversal methods are realized by finite element simulation. Advanced signal processing techniques are used to extract the distinctive nonlinear features. Via the Fast Fourier Transform (FFT) and time-frequency spectral analysis, nonlinear superharmonic components are observed. The reconstructed signals attained from the conventional and virtual time reversal methods are compared and analyzed. Finally, various Damage Indices (DIs), based on the difference between the reconstructed signal and the excitation waveform as well as the amplitude ratio between the superharmonic and the fundamental frequency components are adopted to evaluate the fatigue crack severity. The DIs could provide quantitative diagnostic information for fatigue crack detection. This paper finishes with summary, concluding remarks, and suggestions for future work.

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Damage Detection of Composite Plates by Lamb Wave Ultrasonic Tomography with a Sparse Hexagonal Network Using Damage Progression Trends

Shock and Vibration ◽

10.1155/2014/949671 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 8

Author(s):

C. J. Keulen ◽

M. Yildiz ◽

A. Suleman

Keyword(s):

Damage Detection ◽

Lamb Wave ◽

Composite Structures ◽

Composite Plates ◽

Reconstruction Algorithm ◽

Detection Algorithm ◽

Ultrasonic Tomography ◽

Large Area ◽

Sparse Network ◽

Damage Progression

Lamb wave based structural health monitoring shows a lot of potential for damage detection of composite structures. However, currently there is no agreement upon optimal network arrangement or detection algorithm. The objective of this research is to develop a sparse network that can be expanded to detect damage over a large area. To achieve this, a novel technique based on damage progression history has been developed. This technique gives an amplification factor to data along actuator-sensor paths that show a steady reduction in transmitted power as induced damage progresses and is implemented with the reconstruction algorithm for probabilistic inspection of damage (RAPID) technique. Two damage metrics are used with the algorithm and a comparison is made to the more commonly used signal difference coefficient (SDC) metric. Best case results show that damage is detected within 12 mm. The algorithm is also run on a more sparse network with no damage detection, therefore indicating that the selected arrangement is the most sparse arrangement with this configuration.

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