The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Mingxi Deng - One of the best experts on this subject based on the ideXlab platform.
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response of second harmonic generation of lamb wave propagation to microdamage thickness in a Solid Plate
Wave Motion, 2020Co-Authors: Ning Hu, Mingxi Deng, Han Chen, Yanxun XiangAbstract:Abstract The response features of second-harmonic generation (SHG) of primary Lamb wave propagation to the thickness of microdamage layer (MDL) in a Solid Plate have been theoretically and numerically investigated in this paper. Here the Solid Plate with a MDL is regarded as a double-layered Plate in analysis of nonlinear Lamb wave propagation. On the basis of a second-order perturbation approximation and modal expansion analysis, the physical process of cumulative SHG by primary Lamb wave propagation in a Solid Plate with a MDL has been investigated. The influence of variation in the thickness of MDL on the effect of SHG of primary S 0 mode, which satisfies an approximate phase velocity matching in the low frequency region, has been theoretically analyzed, and then the finite element (FE) simulation has been carried out to validate the results of the theoretical predictions. A close agreement between the theoretical analyses and FE simulations validates the effectiveness of using the effect of SHG of primary S 0 mode for characterizing changes in the thickness of MDL. Moreover, change mechanism of nonlinear acoustic parameter with the thickness of MDL is revealed It is expected that the results obtained can provide a convenient means for accurately characterizing nonhomogeneous microdamage (MDL thickness) in layered Plates.
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Development of general solution of cumulative second harmonic by Lamb wave propagation
2008 IEEE Ultrasonics Symposium, 2008Co-Authors: Mingxi DengAbstract:A straightforward approach has been developed for the general solution of the cumulative second harmonic by Lamb wave propagation in a Solid Plate. The present analyses of second-harmonic generation by Lamb waves focus on the cases where the phase velocity of the fundamental Lamb wave is exactly or approximately equal to that of the dominant double frequency Lamb wave (DFLW). Based on the general solution obtained, the numerical analyses show that the cumulative second-harmonic fields are associated with the position of excitation source and the difference between the phase velocity of the fundamental Lamb wave and that of the dominant DFLW component.
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Second-harmonic generation of ultrasonic guided wave propagation in an anisotropic Solid Plate
Applied Physics Letters, 2008Co-Authors: Mingxi DengAbstract:The nonlinear effect of primary ultrasonic guided wave propagation in an anisotropic Solid Plate is analyzed. The formal solution of the corresponding second-harmonic displacement field is presented. The analytical results clearly indicate that the elastic anisotropy of the Plate material can, in several aspects, influence the efficiency of generation of second harmonic by primary guided wave propagation, and that the corresponding second harmonic is highly sensitive to the elastic anisotropy of the Plate material. The results obtained may provide a potential for accurately characterizing the elastic anisotropy of the Plate material with the effect of second-harmonic generation by ultrasonic guided wave propagation.
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Assessment of fatigue damage in Solid Plates using ultrasonic lamb wave spectra
2008 IEEE Ultrasonics Symposium, 2008Co-Authors: Junfeng Pei, Mingxi DengAbstract:Changes in the mechanical properties of a Solid Plate, induced by fatigue damage, will influence the features of ultrasonic Lamb wave propagation such as dispersion, amplitude and attenuation. The feasibility of using ultrasonic Lamb wave spectra to assess fatigue damage in Solid Plates was briefly discussed. For a given aluminum (2024-T3) sheet, the amplitude-frequency curves before and after cyclic loading were measured with the established experimental setup for ultrasonic Lamb waves. Based on the data measured, the ultrasonic Lamb wave spectra diagrams were established. Clear difference between the two spectra diagrams before and after cyclic loading could be found. It is concluded that ultrasonic Lamb wave spectra may be used to effectively assess the early stages of fatigue damage in Solid Plates.
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Characterization of elastic anisotropy of a Solid Plate using nonlinear Lamb wave approach
Journal of Sound and Vibration, 2007Co-Authors: Mingxi Deng, Jun YangAbstract:Abstract A nonlinear Lamb wave approach is presented for characterizing the in-plane elastic anisotropy of a Solid Plate. The effect of second-harmonic generation in an anisotropic Solid Plate exists and through this the Lamb waves propagate. When the direction of the Lamb wave propagation in an anisotropic Plate changes, the influences of the elastic anisotropy of the Plate material on the second-harmonic generation of the Lamb wave propagation have been analyzed. Theoretical analyses show that the effect of second-harmonic generation of the Lamb wave propagation is closely associated with the elastic anisotropy of the Solid Plate. Based on the theoretical analyses, characterization of the in-plane elastic anisotropy of a given rolled aluminum sheet is experimentally studied. For the different directions of the Lamb wave propagation relative to the rolling direction of the aluminum sheet, the amplitude–frequency curves both of the fundamental waves and the second harmonics of Lamb wave propagation are measured under the condition that the Lamb waves have a strong nonlinearity. It is found that the in-plane elastic anisotropy of the rolled aluminum sheet can clearly affect the efficiency of second-harmonic generation by the Lamb wave propagation. The stress wave factors (SWFs) in acousto-ultrasonic technique are used for reference. Based on the data measured, the normalized SWF curves of the Lamb wave propagation versus the orientation angles relative to the rolling direction of the aluminum sheet are obtained. The results show that the second-harmonic SWF of the Lamb wave propagation varies more sensitively with the orientation angles than does the SWF of the fundamental Lamb wave propagation. It is found that the effect of second-harmonic generation of the Lamb wave propagation can be used to accurately characterize the in-plane elastic anisotropy for the given Solid Plate.
Deng Mingxi - One of the best experts on this subject based on the ideXlab platform.
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second harmonic generation of a plane wave normally incident upon a Solid Plate immersed in liquid
Chinese Physics Letters, 2013Co-Authors: Deng Mingxi, Xiang Yanxun, Wang Ping, L V XiafuAbstract:We theoretically investigate the second-harmonic generation of a plane longitudinal wave normally incident upon a Solid Plate immersed in liquid. The formulation of the reflected second harmonic is derived within the second-order perturbation. Theoretical analysis and numerical simulation indicate that the reflected second-harmonic amplitude increases sensitively with the increase in the nonlinear acoustic parameter of the Plate material at some specific frequencies where the linear reflection coefficient of the normally incident longitudinal wave takes on the minimum value, and that it is independent of the spatial separation between the transmitter/receiver and the Solid Plate. The results obtained provide a means through which the early state of fatigue-induced damage of the Solid Plate (characterized by its nonlinear acoustic parameter) can be sensitively assessed by measuring the reflected second harmonic at the specific frequency where the linear reflection coefficient is minimum.
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Experimental observations of nonlinear effects of SH Plate wave propagation in a Solid Plate
2009Co-Authors: Deng MingxiAbstract:The effect of second-harmonic generation of SH Plate wave propagation in a Solid Plate was briefly analyzed theoretically using perturbation approximation and modal expansion approach for waveguide excitation.Although the effect of second-harmonic generation of a single shear wave in an infinite Solid is weak,a SH Plate wave consisting of two shear waves in a Solid Plate may have a strong nonlinear effect under certain conditions.This paper focused on the experimental verification of the said theoretical prediction.Both the shear-wave wedge transducer for excitation of SH Plate waves and the liquid wedge transducer for receiving the signals of second harmonics were manufactured,and the experimental system for studying the nonlinear effects of SH Plate wave propagation was established.Through the theoretical analyses in detail and the comparative experimental investigations,it was clarified that the clear second- harmonic signal observed under certain conditions was due to the strong nonlinear effect of SH Plate wave propagation. Moreover,the amplitude-frequency curves of second harmonics,with respect to the different distances of SH Plate wave propagation,were measured in the far-field regions.The relationship between the second-harmonic signals of the SH Plate wave and the propagation distance was analyzed near the specific frequency at which the phase velocity of a SH Plate wave was equal to that of a double frequency symmetric Lamb wave.It was experimentally verified that,under certain conditions,the second-harmonic amplitude of SH Plate wave propagation could grow with propagation distance, namely,SH Plate wave propagation could have a strong nonlinearity.
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Cumulative second-harmonic generation of Lamb waves propagating in a two-layered Solid Plate ⁄
Chinese Physics B, 2008Co-Authors: Xiang Yanxun, Deng MingxiAbstract:The physical process of cumulative second-harmonic generation of Lamb waves propagating in a two-layered Solid Plate is presented by using the second-order perturbation and the technique of nonlinear reflection of acoustic waves at an interface. In general, the cumulative second-harmonic generation of a dispersive guided wave propagation does not occur. However, the present paper shows that the second-harmonic of Lamb wave propagation arising from the nonlinear interaction of the partial bulk acoustic waves and the restriction of the three boundaries of the Solid Plates does have a cumulative growth effect if some conditions are satisfied. Through boundary condition and initial condition of excitation, the analytical expression of cumulative second-harmonic of Lamb waves propagation is determined. Numerical results show the cumulative effect of Lamb waves on second-harmonic field patterns.
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Nonlinear ultrasonic guided waves in an anisotropic Solid Plate
2008Co-Authors: Deng MingxiAbstract:The nonlinearity in ultrasonic guided waves was treated as a second-order perturbation of the linear wave motion response.Based on the approaches of second-order perturbation approximation and modal expansion analysis for waveguide excitation,the effect of second-harmonic generation of primary(fundamental)ultrasonic guided wave propagation in an anisotropic Solid Plate has been studied theoretically.The general formal solution to second-harmonic displacement field of primary ultrasonic guided waves has also been presented.It was found that the elastic anisotropy of the Plate material might,in several aspects,influence the effect of second-harmonic generation of guided wave modes. Especially,the changes in the phase velocities of guided waves,caused by the elastic anisotropy of the Plate material, might clearly influence the degree of accumulative growth of double frequency guided wave modes,constituting the field of second harmonic of primary guided waves,with propagation distance.In terms of the results of theoretical analyses and numerical calculations,it was known that there was obvious difference in the nonlinear effect of ultrasonic guided waves in different directions of propagation,and that the second harmonic of primary guided wave propagation was highly sensitive to the elastic anisotropy of the Plate material.The results obtained might provide a theoretical basis for accurate characterization of the elastic anisotropy of the Plate material by using the nonlinear effect of ultrasonic guided wave propagation.
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Reflection of acoustic beam on the surface of Solid Plate
Technical Acoustics, 1998Co-Authors: Deng MingxiAbstract:Analysis and numerical computation have been performed for the reflection of acoustic beam on the Solid Plate surface of layered structure: liquid Solid Plate liquid. The results indicate that the reflected beam will extremely move and expand along the surface of Solid Plate, once incident angle of acoustic beam equals the angle in which the phase of reflection coefficient of plane wave is 180° The analysis method in this paper is of significance for further studying the reflection of acoustic beam on the surface of layered structure.
Tribikram Kundu - One of the best experts on this subject based on the ideXlab platform.
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ultrasonic field modeling in Plates immersed in fluid
International Journal of Solids and Structures, 2007Co-Authors: Sourav Banerjee, Tribikram KunduAbstract:Abstract Distributed Point Source Method (DPSM) is a semi-analytical technique that can be used to calculate the ultrasonic field (pressure, velocity and displacement fields in a fluid, or stress and displacement fields in a Solid) generated by ultrasonic transducers. So far the technique has been used to model ultrasonic fields in homogeneous and multilayered fluid structures, and near a fluid–Solid interface when a Solid half-space is immersed in a fluid. In this paper, the method is extended to model the ultrasonic field generated in a homogeneous isotropic Solid Plate immersed in a fluid. The objective of this study is to model the generation of guided waves in a Solid Plate when ultrasonic beams from transducers of finite dimension strike the Plate at different critical angles. DPSM results for a Solid half-space problem are compared with the finite element predictions to show the superiority of the DPSM technique. The predicted results are also compared with the experimental visualization of the mode patterns of Lamb waves propagating in a glass Plate obtained from stroboscopic photoelastic method. Experimental and theoretical results show good qualitative agreement. The DPSM technique is then applied to study the mode patterns in aluminum Plates immersed in water.
Wang Chenghao - One of the best experts on this subject based on the ideXlab platform.
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Multi-path propagation of acoustical wave and time reversal field in a Solid Plate
2005Co-Authors: Wang ChenghaoAbstract:The multi-path effect of the acoustical wave in a Solid Plate is studied. The multi-reflection and wave conversion of the cylindrical compressional and shear waves, which are excited by an infinite strip on a free surface of the Solid Plate, are analyzed thoroughly by the far-field approximation method. The concise analytical representations of the cylindrical waves are obtained. The time reversal processing is then applied to the propagation of the cylindrical waves and analyzed theoretically and experimentally. It is shown that the waves coming from different array elements and different paths all arrive at the original place after the time reversal operation. It indicates that the time reversal can compensate automatically the wave aberration caused by the multi-path effect. The self-adaptive focusing of the time reversal field is also analyzed quantificationally by the focusing gain and the ratio of the principal to the second lobe. The effects of the focus position and the aperture of the transducer array on the focused field are also investigated. It shows that theoretical and experimental results are consistent to each other very well.
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Multi-path propagation of acoustical wave and time reversal acoustical field in Solid Plate
2005Co-Authors: Wang ChenghaoAbstract:The multi-path effect of the acoustical wave, which is excited by an infinite strip on the free surface of a Solid Plate, is studied. The multi-reflection and wave conversion of the cylindrical compressional and shear waves in Solid Plate are analyzed thoroughly by the ray approach method. The concise analytical representation is obtained. The time reversal processing is then applied to the wave propagation in the Solid Plate and analyzed theoretically and experimentally. It is shown that the waves coming from different arrays and different paths all arrive at the original point after the time reversal operation. It indicates that the time reversal can compensate automatically the wave aberration caused by the multi-path effect. The self-adaptive focusing of the time reversal field is also analyzed quantificationally by the focusing gain and the ratio of the principal to the second lobe. The effects of the focus position and the aperture of the transducer array on the focused field are also investigated. It shows that theoretical and experimental results are consistent to each other very well.
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Time Reversal Self-Focusing in a Solid-Plate Waveguide
Chinese Physics Letters, 2004Co-Authors: Zhang Bi-xing, Wu Hao, Wang ChenghaoAbstract:Acoustic self-adaptive focusing in a Solid-Plate waveguide is theoretically and experimentally studied. The multi-path effect exists in the Solid Plate. A pulse will be widened into a pulsed train and the waveform is distorted. The time-reversal mirrors are applied to study the self-adaptive focusing. The time-reversal effect can be characterized by the focusing gain and the ratio of the principal to the second lobe. It is found theoretically and experimentally that the time-reversal mirrors can compensate automatically for the waveform distortion caused by the multi-path effect.
Joris Degrieck - One of the best experts on this subject based on the ideXlab platform.
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Leaky Rayleigh waves propagating around the corner of a thick Solid Plate: Finite element analysis
The Journal of the Acoustical Society of America, 2007Co-Authors: Ebrahim Lamkanfi, Nico F. Declercq, Wim Van Paepegem, Joris DegrieckAbstract:Finite element simulations reveal the experimentally indicated fact [Declercq et al, J. Appl. Phys. 96(10), 5836–5840 (2004)] that leaky Rayleigh waves propagating along the horizontal surface of a thick fluid‐loaded Solid Plate are transmitted around the corner of the Solid Plate. The experiments indicate that leaky Rayleigh waves are generated around the corner of the Plate, but the experimental evidence is not fully conclusive whether the effect is caused merely by incident Rayleigh waves on the upper surface or by scattering effects when the incident beam interacts with the corner. The current study first investigates the reported experiments by means of the finite element method. Then the model is applied to study leaky Rayleigh waves separately from the incident and reflected bounded beams. It is shown that the Rayleigh waves themselves are the physical origin of the transmission of Rayleigh waves and not the scattering effects caused by the incident bounded beam interacting with the edge of the Plate.
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Finite element analysis of transmission of leaky Rayleigh waves at the extremity of a fluid-loaded thick Plate
Journal of Applied Physics, 2007Co-Authors: Ebrahim Lamkanfi, Nico F. Declercq, Wim Van Paepegem, Joris DegrieckAbstract:A numerical study based on finite element simulations reveals the experimentally indicated fact [N. F. Declercq et al., J. Appl. Phys. 96, 5836 (2004)] that leaky Rayleigh waves propagating along the horizontal surface of a thick fluid-loaded Solid Plate are transmitted around the corner of the Solid Plate. The mentioned experiments are based on the so-called Schoch effect, accompanied by the presence of a null strip in the reflected part of the beam, and phenomena occurring when the incident beam, generating the effect, approaches the edge of the Solid Plate. The referred experiments indicate that leaky Rayleigh waves are generated around the corner of the Plate, but the experimental evidence is not fully conclusive whether the effect is caused merely by incident Rayleigh waves on the upper surface or by scattering effects when the incident beam interacts with the corner. The current study first confirms the reported experiments by means of the finite element method and then proofs that the assumption ma...
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The dependence of Lamb wave stimulation parameters on the impedance difference between upper and lower liquid
The Journal of the Acoustical Society of America, 2004Co-Authors: Nico F. Declercq, Joris Degrieck, Filip Van Den Abeele, Oswald LeroyAbstract:It is known that inhomogeneous plane waves are better capable of stimulating Lamb waves in a Solid Plate than homogeneous plane waves. For each Lamb mode there exists an angle of incidence and an inhomogeneity parameter that maximizes its stimulation. If for example a Solid Plate separates two different liquids (a lower liquid and an upper liquid), then the angle of incidence, for stimulating the same Lamb mode, is unchanged, whereas the inhomogeneity differs compared with the situation where both liquids are equal to each other. If for a given upper liquid and for a given Lamb mode this inhomogeneity difference is plotted as a function of the impedance of the lower liquid, then a linear dependence is noticed. It is noticed that all physical liquids follow this linear tendency. Furthermore, this linearity depends on the generated mode and also on the properties of the Solid Plate. [Work supported by The Flemish Institute for the Encouragement of the Scientific and Technological Research in Industry (I.W.T.).]
