Vibro-acoustic Coupling Research Articles

Research on the wave transmission characteristics of a flexible chamber inserted in the fluid-filled elastic pipeline

In the acoustic calculations of pneumatic pipeline systems, it is commonly assumed that the walls of the pipeline are rigid. It leads to the development of various acoustic theories based on rigid wall. However, in situations involving high-density fluids or thin-walled structures, the propagation of waves in the pipeline becomes complex due to the strong vibroacoustic coupling. In such cases, the wave transmission characteristics calculation methods based on the rigid wall assumption are no longer applicable. This paper employs the pipeline waveguide theory to estimate the wave transmission characteristics in the presence of complex wave behavior within the pipeline. Once the accuracy of the proposed method has been verified, the wave responses of a flexible chamber inserted in the fluid-filled elastic pipeline are analyzed. The analysis shows that the lowest-order fluid-type waves and the lowest-order longitudinal extension waves are found to propagate in the pipeline. The incident lowest-order fluid-type wave and its transmitted wave of the same mode can be successfully separated from other waves. The elasticity of the pipe wall can significantly affect the acoustic characteristics of an expansion chamber. Nevertheless, significant disparities in the wave amplitudes and limited sampling pose challenges to accurate calculations of the transmission loss.

Sound Insulation Characteristic Analysis of Corrugated Core Sandwich Panel by Using Differential Quadrature Finite Element Method

This paper proposes a universal vibroacoustic coupling theoretical analysis model for investigating the sound insulation characteristic of corrugated core sandwich panel (CCSP) under different boundary conditions. The vibroacoustic coupling model consists of CCSP (structural field) and two three-dimensional acoustic cavities which simulate the incident sound field and accept the sound field, respectively. Based on first-order shear deformation plate and shell theories and acoustic theory, the dynamic model of CCSP and three-dimensional acoustic cavities are established by employing the differential quadrature finite element method in conjunction with the energy principle. The coupling of CCSP and three-dimensional acoustic cavities is realized by the velocity continuity condition at the acoustic–structure interfaces. The validation of the vibroacoustic coupling model is verified by comparing the results calculated by the established model with the corresponding results calculated by ABAQUS. The influence of model parameters on the vibroacoustic characteristic of vibroacoustic coupling model is investigated systematically for determining the critical structure parameters which have influence on the vibroacoustic behaviors. The effect of critical structure parameters on the sound insulation characteristic of CCSP is analyzed systematically for the optimization of the sound insulation performance of CCSP and provides theoretical basis and technique guidance.

Vibro-acoustic suppression of metamaterial plates in multi-bandgaps

This paper delves into the vibration and acoustic radiation properties of a metamaterial plate integrated with grouped local resonators (GLRs). The GLRs, consisting of multiple spring-mass resonators arranged in various configurations such as series, parallel, and periodic arrangements, are shown to significantly influence the structural performance of the plate. An advanced Fourier series is implemented to articulate the displacement functions and surface acoustic pressure of the plate. By utilizing the energy principle, a vibro-acoustic coupling model is developed to describe the interaction between the metamaterial plate and the external acoustic field. The theoretical framework is rigorously validated against finite element method simulations, yielding highly congruent results. The local resonance bandgap behavior is explored, and the results reveal that the arrangement and connection strategy of the GLRs determine the stopband characteristics. Multiple resonators connected in series lead to an increased number of stopbands and more pronounced attenuation valleys, whereas multiple resonators connected in parallel or arranged in a periodic array result in an unchanged number of stopbands but a significantly wider stopband bandwidth. Furthermore, transmission characteristic assessments substantiate the vibration dampening efficacy of GLRs, and the marked suppressions in flexural wave propagation are demonstrated within the multiple merged bandgaps. These insights advance the comprehension of localized resonance phenomena in metamaterials and inform the development of sophisticated noise and vibration control strategies.

Innovative design of façade elements to limit wind-induced noise in buildings

Wind-induced noise is often overlooked in building design. This noise can be generated by wind blowing across façade elements or through the various gaps inside buildings. Noise generated by wind-affected façade elements, particularly at higher wind speeds, has received increasing attention since the 2010s. In this paper a comprehensive literature review is carried out to draw general rules for limiting wind-induced noise in buildings. Next, an innovative design was proposed by Metravib Engineering for the Rabat Ibn Sina hospital designed by AIA Ingénierie. A dynamic analysis of these sunshades was then verified using the finite element method to ensure there was no vibro-acoustic coupling between wind excitation and the sunshade's structural modes. Finally, wind tunnel tests confirmed that the noise induced by these façade elements was under control and did not cause any particular annoyance.

An analytical dynamic stiffness method for efficient broadband vibro-acoustic analysis of complex built-up structures

An analytical modelling technique is presented, combining the dynamic stiffness method (DSM) with the spectral DSM (SDSM) for the broadband vibro-acoustic analysis of complex built-up structures. In particular, the structures are modelled exactly by the DSM based on particular solutions tailored for general acoustic or distributed force excitations; whereas the acoustic cavities are modelled by the SDSM where the boundary conditions are described by modified Fourier series with a rapid convergence rate. The vibro-acoustic coupling along the interfaces between the structures and the cavities is achieved by applying the normal velocity continuity condition, leading to a coupling matrix in an analytical manner. Both structural and acoustic cavity elements are assembled directly to model complex vibro-acoustic systems and no extra element discretization is required for both structural and acoustic domains. Consequently, the proposed method uses very few degrees of freedom (DoFs) but describes the broadband vibro-acoustic behaviour highly accurately. It is demonstrated that the proposed method exhibits a predominant advantage over the finite element package COMSOL in terms of accuracy and computational efficiency. This approach also has the potential to serve as the benchmark for a wide range of vibro-acoustic problems.

Vibroacoustic behaviour of a sound cavity enclosed by an acoustic black hole beam

In this paper, we propose a numerical approach to characterize the vibroacoustic coupling between a two-dimensional air cavity and an acoustic black hole (ABH) beam. Displacement variables expanded in terms of Gaussian basis functions are used for both the fluid and the solid, and the coupling condition at the interface between the beam and the cavity is imposed following the null space method (NSM). The approach turns out to be free of numerical instabilities. Concerning the simulations, it is shown that the noise inside the cavity is significantly reduced when the excitation is exerted on the ABH beam as compared to a uniform one. However, if a sound source is placed inside the cavity, no significant noise reduction is achieved by coupling the cavity to an ABH beam instead of a uniform one.

Underbody contribution simulation for vehicle wind-noise

Wind noise is one of the largest sources to the interior noise of modern electric and hybrid vehicles. This noise is encountered when driving on roads and freeways and generate considerable fatigue for passengers on long journeys. Aero-acoustic noise is the result of turbulent and acoustic pressure fluctuations created within the flow. They are transmitted to the passenger compartment via the vibro-acoustic excitation of vehicle surfaces and underbody cavities. Generally, this is the dominant flow-induced source at low frequencies. The transmission mechanism through the vehicle floor and underbody is a complex phenomenon as the paths to the cavity can be both airborne and structure-borne. This study is focused on the floor contribution to wind noise of different type of vehicles, whose underbody structure are largely different. Aero-Vibro-acoustic simulations are performed to clarify the transmission mechanism of the underbody wind noise and contribution. The external fluctuating pressure fields are simulated using computational fluid dynamics based on the Lattice Boltzmann Method (LBM). The vehicle exterior and interior vibro-acoustic coupling and transmission are simulated using subsystems modeled by the finite-element (FEM) or boundary element methods (BEM). The analysis results are discussed and a contribution analysis is proposed to identify potential improvements.

Analytical modelling techniques for efficient broadband noise prediction of high-speed trains

Analytical modelling techniques are presented for broadband noise prediction of high-speed trains. For interior noise problems, train body structures are modelled exactly by the dynamic stiffness method (DSM); whereas the interior acoustic cavities of the train body are modelled by the SDSM where the boundary conditions are described by modified Fourier series with a rapid convergence rate. Finally, the vibro-acoustic coupling model of the train body structures is constructed. For exterior noise problems, exterior train noise models are first formed by experimental data considering the Doppler effect; then both the DSM and theoretical attenuation formulas are used to build noise radiation models for different external environment conditions. The performance of the method is evaluated by predicting the interior sound field distribution of typical cross sections of the train body and the external radiated noise in a tunnel, or in an environment where the acoustic barrier or buildings along railways exist. Numerical results are in good agreement with the those obtained by the finite element method. Thus, the proposed methods can achieve broadband noise prediction highly accurately and efficiently, which can also serve as the benchmark for predicting the radiated noise generated by high‐speed trains.

Wideband Vibro-Acoustic Coupling Investigation in Three Dimensions Using Order-Reduced Isogeometric Finite Element/Boundary Element Method

This study introduces an innovative model-order reduction (MOR) technique that integrates boundary element and finite element methodologies, streamlining the analysis of wideband vibro-acoustic interactions within aquatic and aerial environments. The external acoustic phenomena are efficiently simulated via the boundary element method (BEM), while the finite element method (FEM) adeptly captures the dynamics of vibrating thin-walled structures. Furthermore, the integration of isogeometric analysis within the finite element/boundary element framework ensures geometric integrity and maintains high-order continuity for Kirchhoff–Love shell models, all without the intermediary step of meshing. Foundational to our reduced-order model is the application of the second-order Arnoldi method coupled with Taylor expansions, effectively eliminating the frequency dependence of system matrices. The proposed technique significantly enhances the computational efficiency of wideband vibro-acoustic coupling analyses, as demonstrated through numerical simulations.

Vibro-acoustic coupling analysis of dynamic performance of the double panel system with mechanical links

The theoretical prediction model for the dynamic performance of a double panel system that takes into account the effect of mechanical links is developed in this paper. The double panel system is established considering both the vibro-acoustic coupling and the effect of the mechanical links between two flexible panels. Firstly, the modal characteristics of the double panel system are analyzed and compared with the results calculated by the finite element method. The accuracy and efficiency of the proposed model have been validated. Subsequently, the forced response of the double panel system under different external excitations is studied. It is shown that the mechanical link resulted in less response level of the double panel system in in low frequency range due to the structural path in the energy transmission of the double panel system. Finally, the effect of the mechanical link parameters on the dynamic performance of the double panel system is discussed. The results reveal that the stiffness coefficients, location distributions, and number of mechanical links can significantly influence the dynamic behavior of the double panel system. Therefore, the theoretical model can be used in optimization techniques to improve the sound transmission characteristics of the double panel system.

Active feedback control on acoustic radiation of metastructure shell with low-frequency and broadband characteristics

Due to the tunable characteristics of elastic waves, the vibroacoustic coupling behavior of a mechanical metastructure is a hot topic of underwater vehicles. In this work, a metastructure shell with active feedback control is presented and fabricated. The dynamic effective density and sound pressure level are derived to find the influences of acceleration and displacement feedback control. Different from a single cylinder, a double cylinder structure has both in-phase and anti-phase modes. Numerical results are obtained by Fourier transform and harmonic series expansion. With the introduction of an active feedback control system, the reduction of acoustic radiation shows low-frequency and broadband characteristics. In addition, finite element simulation is applied to support numerical results and present vibroacoustic characteristics. Finally, an experiment is performed in the anechoic chamber to illustrate the quiet metastructure shell, which can be applied to new designs of underwater vehicles.

The Vibro-Acoustic Characteristics Analysis of the Coupled System between Composite Laminated Rotationally Stiffened Plate and Acoustic Cavities

In order to study vibro-acoustic characteristics between composite laminated rotationally stiffened plate and acoustic cavities in the coupled system, first-order shear deformation theory (FSDT) and modified Fourier series are used to construct a unified analysis model. The involved coupled systems primarily encompass three types: the coupled system between composite laminated rotationally stiffened plate and cylindrical-cylindrical cavities, spherical-cylindrical cavities, and conical-cylindrical cavities. First, the first-order shear deformation theory and the modified Fourier series are applied to construct the allowable displacement function of the composite laminated rotationally stiffened plate and the allowable sound pressure function of the acoustic cavities. Second, the energy functionals for the structural domain and the acoustic field domain are established, respectively. According to the continuity condition of the particle vibration velocity at the coupling boundary between the composite, laminated cylindrical shell and the enclosed cavity, the coupling potential energy between the stiffened plate and two acoustic cavities is introduced to obtain the energy functional of the coupled system. Third, the Rayleigh-Ritz method is utilized to solve the energy functional and, when combined with artificial virtual spring technology, the suggested theory may be used to study the vibro-acoustic characteristics of a coupled system with arbitrary elastic boundary conditions. Finally, based on validating the fast convergence and correctness of the model, this paper will analyze the impact of crucial parameters on vibro-acoustic characteristics. Furthermore, by incorporating internal point forces and point-sound source stimulation, a steady-state response analysis of the coupled system will be conducted. This research can give a theoretical foundation for the vibration and noise reduction of a vibro-acoustic coupling system.

The acoustic radiation analysis of SFGP conical shell

The shell of revolution made of sandwich functionally graded material (SFGM) has broad applications in engineering. Pores are inevitable in processing SFGM, making it complex for the vibro-acoustic characteristics of the structure. To analyze the acoustic radiation mechanism of sandwich functional gradient porous materials (SFGP) shells deeply, a theoretical model for vibro-acoustic coupling of SFGP shells based on a semi-analytical approach is proposed. The spectral boundary element approach is used to simulate the sound field while the energy method is utilized for representing the structural field. The substructure scheme is introduced, resulting in a uniform division of both the structural field and the sound field into several segments. Similarly, both the displacement and sound pressure are depicted in an identical manner, with the meridional direction expanded using the Legendre series and the circumferential direction expanded using the Fourier series. By introducing the virtual work done by the sound pressure, the structural and sound fields are coupled to form the vibro-acoustic coupling equation, which is solved using the strong coupling approach. The present method exhibits outstanding convergence and precision, showcasing a strong agreement in vibro-acoustic response results when compared to prior research. Since the conical shell is one of the most widely applicable shells of revolution, this paper takes the conical shell as the research object to study. Following the proposed methodology, we delve into the examination of the roles played by various circumferential wave number modes in influencing the vibro-acoustic response of SFGP conical shells. Building upon this groundwork, an investigation is conducted into the influence of factors such as material gradient index, porosity, and pore distribution on the vibro-acoustic characteristics of SFGP conical shells.

A fast Chebyshev spectral approach for vibroacoustic behavior analysis of heavy fluid-loaded baffled rectangular plates with general boundary conditions

A computationally efficient Chebyshev spectral approach is proposed to solve the vibroacoustic response of heavy fluid-loaded baffled rectangular plates. The governing equations for the displacements of motion in rectangular plates and the sound pressure in the Helmholtz integral are formulated using high-order, first-class Chebyshev polynomial expansions. This formulation is combined with Gauss-Chebyshev-Lobatto sampling. The quadruple integral encountered in solving the work done by the heavy fluid on the plate is reformulated into the configuration of a tensor product. The approach significantly reduces the computation time for solving the acoustic equations, bringing the vibration response of fluid-loaded plates closer to that of vacuum plates and limiting it to just a few seconds. The elastic boundary conditions of the rectangular plates are simulated using linear and rotational springs. Predictions of vibroacoustic behavior, including plate velocity, sound pressure, sound power, and radiation efficiency, are validated against literature results. The accuracy and efficiency of the Chebyshev spectral approach for the vibroacoustic coupling systems are demonstrated by the presence of exemplary agreements. Furthermore, this study investigates the effect of boundary conditions, geometric characteristics, and damping variables on the vibroacoustic behavior of rectangular plates.

Verification on prediction method of floor impact sound using vibro-acoustic coupling effect

The impact noise generated in concrete structures exhibits complex behavior due to the interaction between vibration and sound, making it difficult to predict. To achieve accurate predictions, it is important to consider the interaction between vibration and sound and input reliable data. In this study, a governing equation that considers the interaction between vibration and sound was proposed and validated using relatively reliable vibration data as input. Vibration and sound data were obtained from a mock-up house built with a structure similar to that of an actual residential building. The vibration data was analyzed using time history and modal decomposition to confirm the interaction between vibration and sound. Subsequently, the proposed governing equation was used to calculate the sound data by inputting the vibration data, which was then compared and analyzed against the measured data. In the time history analysis, it was observed that the calculated data after 0.8 seconds exhibited relatively less attenuation, suggesting a higher damping ratio in the mock-up house than anticipated. Furthermore, the modal decomposition comparison revealed a slight shift in the mode frequency from 43.0 Hz to 43.6 Hz, and the spectrum showed larger values in the calculated data, which can be attributed to the damping ratio. Further research on the damping ratio in residential buildings is planned to improve the accuracy of the prediction in the vibration-sound system.

On the Alignment of Acoustic and Coupled Mechanic-Acoustic Eigenmodes in Phonation by Supraglottal Duct Variations.

Sound generation in human phonation and the underlying fluid-structure-acoustic interaction that describes the sound production mechanism are not fully understood. A previous experimental study, with a silicone made vocal fold model connected to a straight vocal tract pipe of fixed length, showed that vibroacoustic coupling can cause a deviation in the vocal fold vibration frequency. This occurred when the fundamental frequency of the vocal fold motion was close to the lowest acoustic resonance frequency of the pipe. What is not fully understood is how the vibroacoustic coupling is influenced by a varying vocal tract length. Presuming that this effect is a pure coupling of the acoustical effects, a numerical simulation model is established based on the computation of the mechanical-acoustic eigenvalue. With varying pipe lengths, the lowest acoustic resonance frequency was adjusted in the experiments and so in the simulation setup. In doing so, the evolution of the vocal folds' coupled eigenvalues and eigenmodes is investigated, which confirms the experimental findings. Finally, it was shown that for normal phonation conditions, the mechanical mode is the most efficient vibration pattern whenever the acoustic resonance of the pipe (lowest formant) is far away from the vocal folds' vibration frequency. Whenever the lowest formant is slightly lower than the mechanical vocal fold eigenfrequency, the coupled vocal fold motion pattern at the formant frequency dominates.

An investigation of magnetic and vibroacoustic coupling in the balanced armature receiver

The balanced armature receiver is an electromagnetic transducer, used in hearing aids and high-end hearables. Understanding and predicting the coupling between the electromagnetic behaviour and mechanical motion in a comprehensive fashion is fundamental for our research towards a complete multiphysics description. We present a 3D finite element model (FEM) of the magnetic circuit that captures the effect of fringing and stray fields in the receiver, to accurately predict the force on the armature. We compare this finite element model to lumped parameter models (LEM) representing the electrical and mechanical domains. The simulation results are matched to laser vibrometer and electrical impedance measurements of the device.

On the radiation of sound from an immersed cylindrical shell close to the sea surface

Numerical methods for the prediction of underwater radiated noise from immersed structures play a key role in the naval and offshore industry to ensure high acoustic performance of systems or to preserve natural habitats. Most of the approaches so far assume that the surrounding fluid is homogeneous and unbounded. However, in many situations the structure can be close to interfaces, namely the sea surface and the sea bottom, such as navigation of underwater vehicles in shallow waters. The Lloyd's mirror effect describes the interference phenomena occurring when a sound source is close to the sea surface. This effect is easily accounted for with a source image approach, while the strong vibro-acoustic coupling between the structure and the interface is more complicated to deal with. In this context, an analytical method has recently been developed to predict the vibro-acoustic behaviour of an infinite length cylindrical shell close to the surface, based on the shell equations and Graf's addition theorem. In the present work, we compare this approach to a simplified one where the strong interactions between the surface and the structure are not considered. Results highlight these effects on a typical underwater structure

Speech extraction from vibration signals based on deep learning.

Extracting speech information from vibration response signals is a typical system identification problem, and the traditional method is too sensitive to deviations such as model parameters, noise, boundary conditions, and position. A method was proposed to obtain speech signals by collecting vibration signals of vibroacoustic systems for deep learning training in the work. The vibroacoustic coupling finite element model was first established with the voice signal as the excitation source. The vibration acceleration signals of the vibration response point were used as the training set to extract its spectral characteristics. Training was performed by two types of networks: fully connected, and convolutional. And it is found that the Fully Connected network prediction model has faster Rate of convergence and better quality of extracted speech. The amplitude spectra of the output speech signals (network output) and the phase of the vibration signals were used to convert extracted speech signals back to the time domain during the test set. The simulation results showed that the positions of the vibration response points had little effect on the quality of speech recognition, and good speech extraction quality can be obtained. The noises of the speech signals posed a greater influence on the speech extraction quality than the noises of the vibration signals. Extracted speech quality was poor when both had large noises. This method was robust to the position deviation of vibration responses during training and testing. The smaller the structural flexibility, the better the speech extraction quality. The quality of speech extraction was reduced in a trained system as the mass of node increased in the test set, but with negligible differences. Changes in boundary conditions did not significantly affect extracted speech quality. The speech extraction model proposed in the work has good robustness to position deviations, quality deviations, and boundary conditions.

Soft solid subwavelength plates with periodic inclusions: Effects on acoustic Transmission Loss

Dispersion and scattering properties of a soft solid plate with solid cylindrical inclusions embedded in are theoretically and numerically reported in this work. The system is numerically analyzed considering both the vibroacoustic coupling and the presence of viscoelastic losses. In addition to the mechanical properties of the soft solid plate that allows the shift of the higher order Lamb modes to the low audible frequency domain, the presence of the inclusions introduces resonant and antiresonant phenomena in the subwavelength regime, leading to an elastic band-gap and a destructive modal interference in the soft solid plate able to interact with each other. These phenomena are used to design a system with strong transmission loss, breaking the mass law by 15 dB, and with subwavelength dimensions as the thickness is 32 times smaller than the equivalent wavelength in air. These performances are both computed and tested experimentally using a standard measuring process.