Wave Propagation In Thin Plate Research Articles

Hybrid experimental/computational approach to Time Reversal source localization in thin plates using image source method

Standard approaches to source localization usually rely on trilateration, using signals detected at multiple receiving points, with further research focused on improving localization robustness and reducing the number of sensors required. Time Reversal (TR) is a valid alternative, however it is often difficult to define a reliable hybrid (computational/experimental) approach, particularly in the case of plates where dispersive properties of the propagating waves play a crucial role to obtain focusing. In this paper, we present an analytical method that describes wave propagation in thin plates, accounting for edge reflections and dispersive properties, and validate it by comparison to experimental data. The Image Source Method (ISM), employed and extended in this study, provides an analytical means of Green's function computation through multiple edge-reflected propagation paths and proves to be reliable and fast to study propagation of Lamb waves in thin plates. A one-channel hybrid TR approach based on ISM is also proposed, utilizing experimental signals transferred to the model for backpropagation computation. In particular, the determination of the optimal signal duration to be time-reversed is discussed.

Design and Robustness Evaluation of Valley Topological Elastic Wave Propagation in a Thin Plate with Phononic Structure

Based on the concept of band topology in phonon dispersion, we designed a topological phononic crystal in a thin plate for developing an efficient elastic waveguide. Despite that various topological phononic structures have been actively proposed, a quantitative design strategy of the phononic band and its robustness assessment in an elastic regime are still missing, hampering the realization of topological acoustic devices. We adopted a snowflake-like structure for the crystal unit cell and determined the optimal structure that exhibited the topological phase transition of the planar phononic crystal by changing the unit cell structure. The bandgap width could be adjusted by varying the length of the snow-side branch, and a topological phase transition occurred in the unit cell structure with threefold rotational symmetry. Elastic waveguides based on edge modes appearing at interfaces between crystals with different band topologies were designed, and their transmission efficiencies were evaluated numerically and experimentally. The results demonstrate the robustness of the elastic wave propagation in thin plates. Moreover, we experimentally estimated the backscattering length, which measures the robustness of the topologically protected propagating states against structural inhomogeneities. The results quantitatively indicated that degradation of the immunization against the backscattering occurs predominantly at the corners in the waveguides, indicating that the edge mode observed is a relatively weak topological state.

Design of continuously deformable topological phononic structures and their application to elastic waveguides

We design a topological phononic crystal in a thin plate, aiming at the development of an efficient elastic waveguide based on the concept of band topology in phonon dispersion. We adopt a snowflake-like structure for the crystal unit cell and search for the optimal structure that exhibits the topological phase transition of the three-dimensional phononic crystal by changing the unit cell structure. The bandgap width can be adjusted by varying the length of the branch of the snow side, and a topological phase transition occurs at the unit cell structure with three-fold rotational symmetry. Elastic waveguides based on edge modes appearing at interfaces between crystals with different band topologies are designed, and their transmission efficiency is evaluated numerically and experimentally. The results demonstrate robustness of the elastic wave propagation in thin plates. Moreover, we experimentally estimate a robustness of the topologically protected propagating states against structural inhomogeneities. The results obtained in this study pave the way for practical development of new surface acoustic wave technologies for high-frequency communication devices.

Estimation of the Propagation of Flexural Waves in Thin Plates Using a Single Low-Cost Sensor

This paper demonstrates how flexural wave propagation in a thin plate can be modeled by estimating the combined effect of the excitation source signal and the impulse response of the ultrasonic sensor. The wave propagation in the plate is modeled using the wave equation for the flexural wave mode. A theoretical model for flexural wave propagation in thin plates has been derived, and it has been compared with measurements excited by tapping gently on the surface. The combined effects of the excitation source signal and the impulse response of the low-cost piezoelectric sensor are modeled using finite-impulse response and/or infinite-impulse response filters. Thereafter, the performances of the selected filters are compared on estimating the wave propagation in a thin quartz glass plate. Results indicate that the most accurate estimation of wave propagation has been obtained using a linear phase filter which attributes all dispersions to the flexural wave.

Modelling Wave Propagation in Thin Plates with the pectral Modal Method

Modelling Wave Propagation in Thin Plates with the pectral Modal Method

Dissemination of Waves in Thin Plates

The article deals with the wave propagation in thin plate. A wave was caused by the impact force. In the first part of an article the Kirchhoff's theory of thin isotropic plate is given. It is a vertical displacement w, angles of rotation tangent φx and φy, bending stresses σx, σy, shear strength τyx = τyx, shear strength from displacement forces τxz, τyz. In the second part of an article is solved a Kirchhoff's theory by analytically in MATLAB programme. Analytically were solved only displacements u, v and velocity u ̇,v̇ . The solution is performed for two plate materials - aluminium and steel. By result are deformations and velocities graphs in the x-axis and the y-axis at the measurements points given. In the conclusion of an article is comparing of individual deformations and velocities graphs.

Design and Dynamic Analysis of Bending Waves Waveguide Based on Coordinate Transformation Theory

The finite embedded coordinate transformation theory is introduced into the elastic dynamic equation of bending waves, a design of bend waveguide to control bending waves to bend at arbitrary angel is proposed. The formula to describe the transformed materials properties in an elastic thin plate is obtained, which contains anisotropic heterogeneous Young modulus and a radially dependent mass density. Through homogenization of layered periodic composite materials, the anisotropic materials are dispersed into discrete layered isotropic materials. The simulation model of the waveguide is built, and full-wave dynamic simulations of the model are analyst with finite element method. Numerical analysis results show that the waveguide consisting of 10 layers alternating two types of isotropic elastic materials can achieve effective control of the bending wave propagation in thin plates, it works over the frequency range [1500, 10000] hertz with ultra-wideband characteristics. The study can provide technological approaches to bending waves control in thin plates, and it is expected to provide potential applications in isolating structures from vibrations.

Rectification of Lamb wave propagation in thin plates with piezo-dielectric periodic structures

Based on a heterostructured plate consisting of piezoelectric-ceramic/epoxy-resin composites with different periodicities, we design a novel acoustic diode for the symmetrical/asymmetrical (S/A) mode of Lamb wave at audible ranges. The acoustic diode is constructed with two parts, i.e., the mode conversion part and the mode selection part, and the mode conversion mechanism at the interface is applied to the mode hybridization from S to S+A and for the mode conversion from A to S. The phonon band structures for each part are calculated and optimized so that the mode selection is realized for a specific mode at the junction. Finite-element simulations prove that the proposed acoustic diode achieves efficient rectification at audio frequency ranges for both S and A mode incidences of the Lamb wave.

1P1-8 Rectification of Lamb wave propagation in thin plates with piezo-dielectric periodic structures

1P1-8 Rectification of Lamb wave propagation in thin plates with piezo-dielectric periodic structures

Optimizing a spectral element for modeling PZT-induced Lamb wave propagation in thinplates

Use of surface-mounted piezoelectric actuators to generate acoustic ultrasound has beendemonstrated to be a key component of built-in nondestructive detection evaluation (NDE)techniques, which can automatically inspect and interrogate damage in hard-to-access areasin real time without disassembly of the structural parts. However, piezoelectric actuatorscreate complex waves, which propagate through the structure. Having the capability tomodel piezoelectric actuator-induced wave propagation and understanding its physics areessential to developing advanced algorithms for the built-in NDE techniques. Therefore, theobjective of this investigation was to develop an efficient hybrid spectral elementfor modeling piezoelectric actuator-induced high-frequency wave propagation inthin plates. With the hybrid element we take advantage of both a high-orderspectral element in the in-plane direction and a linear finite element in the thicknessdirection in order to efficiently analyze Lamb wave propagation in thin plates.The hybrid spectral element out-performs other elements in terms of leadingto significantly faster computation and smaller memory requirements. Use ofthe hybrid spectral element is proven to be an efficient technique for modelingPZT-induced (PZT: lead zirconate titanate) wave propagation in thin plates. Theelement enables fundamental understanding of PZT-induced wave propagation.

Observation of Piezoelectrically Induced Lamb Wave Propagation in Thin Plates by Use of Speckle Interferometry

Lamb waves have shown to be favorably applicable in the development of health monitoring systems in structural mechanics since they show reflections, refractions, as well as mode conversions at fault locations. For the observation of the wave propagation, the double pulsed electronic speckle pattern interferometry (ESPI) as a high precision, full-field, and non-contact measurement technique is under investigation in this work. First, it is shown that symmetric and antisymmetric Lamb waves can be captured in a faultless plate. Moreover, mode conversions are observed at stiffness discontinuities in a specially prepared plate. Finally, a riveted lightweight structure is under investigation. In these experiments, mode conversions indicate the location of the rivets.

Acoustical wave propagator for time-domain flexural waves in thin plates.

In this paper, an explicit acoustical wave propagator technique is introduced to describe the time-domain evolution of acoustical waves in two-dimensional plates. A combined scheme with Chebyshev polynomial expansion and fast Fourier transformation is used to implement the operation of the acoustical wave propagator. Through this operation, the initial wave packet at t = 0 is mapped into the wave packet at any instant t > 0. By comparison of the results of the exact analytical solution and the Euler numerical method, we find that this new Chebyshev-Fourier scheme is highly accurate and computationally effective in predicting the acoustical wave propagation in thin plates. This method offers an opportunity for future study of dynamic stress concentration and time-domain energy flow in coupled structures.

Experimental verification of the opposite effect of fluid loading on the velocity of dilatational waves in thin plates and rods

In a recent paper [J. Acoust. Soc. Am. 102, 3478 (1997)], it was demonstrated by analytical means that radiation loading increases the velocity of dilatational waves in immersed thin plates, but decreases it in thin rods. The main goal of this paper is to verify experimentally the predicted opposite effect, which is particularly interesting because in almost every respect, the lowest-order dilatational modes of wave propagation in thin plates and rods are very similar. Experimental verification of the predicted small radiation-induced velocity change is rather difficult, partly because of the accompanying strong attenuation effect caused by radiation losses, and partly because of the presence of an additional velocity change caused by viscous drag even in low-viscosity fluids like water. In spite of these inherent difficulties, the presented experimental results provide unequivocal verification of the earlier theoretical predictions.

Flexural Wave Propagation in a Thin Plate with Circular Holes

This paper deals with the problems of transverse and torsional wave propagation in an infinite thin elastic plate with circular holes. The dynamical moment concentrations along holes are obtained and compared with those for a single hole. When the wave length becomes infinity, it is ascertained that the dynamical solutions tend to statical ones.