Acoustic-structure Interaction Research Articles

The dynamic response of composite auxetic re-entrant honeycomb structure subjected to underwater impulsive loading

The researches on dynamic responses of underwater impulsive loading have been conducted. However, the previous study mainly concentrated on metal sandwich structure and fixed supported boundary. The relative research on composite auxetic re-entrant honeycomb structure and simply supported boundary are rarely. In this paper, the effect of the gradient form and relative density on impact resistance performance of composite auxetic re-entrant honeycomb structure was experimentally and numerically investigated. The one-stage light gas gun was applied to provide initial kinetic energy of the fly plate, and the diffuser-type shock tube was utilized to generate and propagate exponential decaying shock wave. The pressure–time curve was respectively amplified and recorded by the charge amplifier and oscilloscope. The response speed, final deflection of rear panel and failure mode of cores and panels were used to evaluate impact resistance of composite auxetic re-entrant honeycomb structures. Moreover, acoustic-structure interaction algorithm was applied to simulate impact course of specimens in Abaqus/Explicit. The results between experiment and numerical simulation exhibited good consistency. The results indicated that the positive gradient form could excessively slow down response speed of rear panel by dissipating energy of shock wave, and the average gradient demonstrated smaller final displacement of rear panel and less failure compared with graded structures.

Broadband topology optimization of three-dimensional structural-acoustic interaction with reduced order isogeometric FEM/BEM

This paper presents a model order reduction method to accelerate broadband topology optimization of structural-acoustic interaction systems by coupling Finite Element Methods and Boundary Element Methods. The finite element method is used for simulating thin-shell vibration and the boundary element method for exterior acoustic fields. Moreover, the finite element and boundary element methods are implemented in the context of isogeometric analysis, whereby the geometric accuracy and high order continuity of Kirchhoff-Love shells can be guaranteed and meantime no meshing is necessary. The topology optimization method takes continuous material interpolation functions in the density and bulk modulus, and adopts adjoint variable methods for sensitivity analysis. The reduced order model is constructed based on second-order Arnoldi algorithm combined with Taylor's expansions which eliminate the frequency dependence of the system matrices. Numerical results show that the proposed algorithm can significantly improve the efficiency of broadband topology optimization analysis.

Resonance mechanism of flapping wing based on fluid structure interaction simulation

Certain insect species have been observed to exploit the resonance mechanism of their wings. In order to achieve resonance and optimize aerodynamic performance, the conventional approach is to set the flapping frequency of flexible wings based on the Traditional Structural Modal (TSM) analysis. However, there exists controversy among researchers regarding the relationship between frequency and aerodynamic performance. Recognizing that the structural response of wings can be influenced by the surrounding air vibrations, an analysis known as Acoustic Structure Interaction Modal (ASIM) is introduced to calculate the resonant frequency. In this study, Fluid Structure Interaction (FSI) simulations are employed to investigate the aerodynamic performance of flapping wings at modal frequencies derived from both TSM and ASIM analyses. The performance is evaluated for various mass ratios and frequency ratios, and the findings indicate that the deformation and changes in vortex structure exhibit similarities at mass ratios that yield the highest aerodynamic performance. Notably, the flapping frequency associated with the maximum time-averaged vertical force coefficient at each mass ratio closely aligns with the ASIM frequency, as does the frequency corresponding to maximum efficiency. Thus, the ASIM analysis can provide an effective means for predicting the optimal flapping frequency for flexible wings. Furthermore, it enables the prediction that flexible wings with varying mass ratios will exhibit similar deformation and vortex structure changes. This paper offers a fresh perspective on the ongoing debate concerning the resonance mechanism of Flexible Flapping Wings (FFWs) and proposes an effective methodology for predicting their aerodynamic performance.

A coupling FEM/BEM method for acoustic-structural interaction problems in uniform relative motion between structure source and fluid

When a vibrating thin structure moves in a heavy flow field, the effect of sound waves on the structure cannot be ignored. This effect is especially pronounced when the relative velocity of the structure and the flow field increases. The hybrid numerical method of finite element method (FEM) and convective boundary element method (BEM) is proposed to solve acoustic-structural interaction problems in uniform relative motion between structure source and fluid. Besides, an acoustic-analogy Lorentz transform is proposed to handle the direct convective boundary integral equation (BIE), which makes the convective BIE has the same form as traditional BIE so that there are no more convective terms and extra singular integrals. The continuity condition at the fluid-structure interface is also proposed to generate the coupling equation. Compared with the traditional FEM, this hybrid method has the advantages of greatly reducing the number of finite elements outside the structure as well as automatically satisfying the radiation condition at far field. And compared with the direct convective BIE, this method reduces the computational complexity and time. It is potential to deliver a solver with higher accuracy and less memory consumption. Some numerical examples are designed to study the influence of the convective effect. Keywords: Acoustic-structural interaction, Finite element method, Boundary element method, FEM-BEM coupling

Acoustic Analysis and Experimental Validation of Acoustic Metamaterial

In this study, a unique sound insulation performance of a lightweight acoustic metamaterial consisting of a stiff honeycomb plate coated with a thin rubber membrane was experimentally demonstrated. An acoustic transmission measurement of the acoustic metamaterial showed that the sound insulation performance of the acoustic metamaterial exceeded the mass law predicted performance in three frequency ranges. An analysis of the acoustic-structure interaction revealed that these unique sound insulation phenomena were due to the cancellation between two high-order eigenmodes of the periodic structure or a high-order eigenmode of the periodic structure and an eigenmode of the membrane in each honeycomb cell. Subsequently, a prototype of this acoustic metamaterial was applied to a vehicle and its effectiveness on vehicle interior noise was investigated. The results show that such materials can further improve the level of quietness with weight reduction in vehicles and other transportation applications.

Sound transmission loss analysis of double-walled sandwich functionally graded carbon nanotube-reinforced composite magneto-electro-elastic plates under thermal environment

Sandwich structures with functionally graded (FG) cores have gained interest in vibroacoustic applications. This article considers the vibroacoustic properties of double-walled sandwich magneto-electro-elastic (MEE) plates with a functionally graded carbon nanotube-reinforced composite (FG-CNTRC) core layer in a thermal environment. A coupled multiphysics model is developed based on third-order shear deformation theory (TSDT) and acoustic-structure interaction. Special attention is paid to the transmission loss of this arrangement for simply supported and clamped boundaries for four different kinds of CNT distributions, namely, UD, FG-V, FG-O, and FG-X. Sound velocity potential, normal velocity continuity conditions, and Hamilton's principle are used to generate the coupled vibroacoustic equations, which are then solved using the Galerkin method. The effects of boundary conditions, CNT distributions, cavity depth, multiphysics coupling fields, and temperature on the STL are comprehensively studied. The results provide guidelines for tailoring the dynamic response of these materials to achieve enhanced acoustic insulation performance. It enhances fundamental understanding and enables the engineering design of multilayered composite panels with optimized vibration and noise control capabilities.

On weak/Strong Attractor for a 3-D Structural-Acoustic Interaction with Kirchhoff–Boussinesq Elastic Wall Subject to Restricted Boundary Dissipation

On weak/Strong Attractor for a 3-D Structural-Acoustic Interaction with Kirchhoff–Boussinesq Elastic Wall Subject to Restricted Boundary Dissipation

FEM Investigation of the Air Resonance in a Cretan Lyra

Cretan lyra is a stringed instrument very popular on the island of Crete, Greece, and an important part of its musical tradition. For stringed musical instruments, the air mode resonance plays a vital part in their sound, especially in the low frequency range. For this study, the air mode resonance of a Cretan lyra is investigated with the use of finite element method (FEM). Two different FEM acoustic models were utilized: First, a pressure acoustics model with the Cretan lyra body treated as rigid was used to provide an approximate result. Secondly, an acoustic–structure interaction model was applied for a more accurate representation. In addition, acoustic measurements were performed to identify the air mode resonance frequency. The results of this study reveal that the acoustic–structure interaction model has a 3.7% difference regarding the actual measurements of the resonance frequency. In contrast, the pressure acoustics solution is approximately 13.8% too high compared with the actual measurements. Taken together, the findings of this study support the idea that utilizing the FEM acoustic–structure interaction models could possibly predict the vibroacoustic behavior of musical instruments more accurately, which in turn can enable the determination of key aspects that can be used to control the instrument’s tone and sound quality.

Damping characteristics and sound transmission loss of finite composite plates with frequency dependent constrained viscoelastic interlayer

This paper proposes a sublaminate layer-wise finite element modeling method to accurately evaluate the damping and sound insulation characteristics of composite constrained layer damping plates. It incorporates the frequency-dependent property of viscoelastic interlayer into fully coupled structure-acoustic interaction equations, and employs the generalized high-order displacement hypothesis with tailored polynomial series expansion. The method is applicable to various boundary conditions and material layer combinations. Validation is conducted using numerical and experimental data. Parametric study identifies optimal thickness and stiffness for maximizing modal loss factor. Additionally, sound insulation performance is examined in narrow frequency bands, highlighting the damping enhancement of viscoelastic interlayer.

A Numerical Study of Collective Cell Migration in a Microchannel Driven by Surface Acoustic Wave (SAW) Device

Collective cell migration is involved in a variety of biological contexts, including tissue morphogenesis, wound healing, and cancer invasion. Many studies have revealed that chemical, mechanical, and electrical stimulation all affect cell migration. Although an acoustic stimulus has been shown to influence cell migration in the past, the underlying mechanism is still unknown. A computational model that accounts for acoustic–structure interaction was constructed in this study to simulate the formation of a surface acoustic wave (SAW) field and the application of the acoustic pressure field on collective cell migration. A group of cells within a microchannel device and two ports of interdigitated transducers (IDTs) with different wavelengths were modeled. The stresses within cells were investigated as it was influenced by substrate displacement and pressure acoustic in the cell media generated by the SAW device. As a result, we observed the local stress within cells near the solid-fluid interfaces. For propagating SAW, the shorter wavelength of IDTs (600 μm) attributed to high stress at the cell’s top and bottom as compared to the SAW device with the longer wavelength (1000 μm). The standing SAW occurred underneath collective cells. The results of standing SAW on cell stress at the bottom confirm that the SAW device can be useful to regulate the abnormalities cellular activities associated with cell migration.

Numerical Study of Acoustic-Structure Interaction of Selected Helicoidal Resonator with Flexible Helicoidal Profile

The paper presents the results of numerical studies of acoustic-structure interaction of selected helicoidal resonator with helicoidal profile made of an elastic material. Considered a well-recognized acoustic system for one representative type of acoustic helicoidal resonator with two resonant frequencies that correspond to previous studies of the author. Due to the large range of flexible materials to study, this work focuses on the change of material density, Poisson’s ratio and Young’s modulus as the basic parameters describing the properties of elastic materials. The results indicate a significant interaction between the acoustic attenuation performance of helicoidal resonator and elasticity of the helicoidal profile. These interactions are most evident in the frequency range in which the helicoidal resonator is revealed to be effective acoustic damper.

Noise radiation analysis of the hermetic reciprocating compressor by considering acoustic-structure interaction

Noise radiation analysis of the hermetic reciprocating compressor by considering acoustic-structure interaction

Evaluating dynamic behaviour of a concrete dam using modal analysis

Modal Analysis is the most fundamental aspect of the dynamic study of structures. It is used to determine the vibrational characteristics of linear elastic structures. It suggests the natural frequencies and mode shapes, which are essential to understand the dynamic behaviour of that structure. In this study, Shahpurkandi Dam, a concrete gravity dam of height 55.5 m is considered in order to investigate its dynamic properties using the finite element package ‘ANSYS’. Furthermore, structure-acoustic interaction is explicitly modelled, and a case of the full reservoir is taken into account to analyze the modal response of the dam. The first 6 mode shapes are extracted, and the total displacement is recorded through the numerical simulation of the direct solver including the block Lanczos method. This study shows the maximum deformation is recorded for the first fundamental natural frequency, which is 0.0039 mm at the crest of the dam. Henceforth, it is essential to monitor the mode shape and natural frequency of initial modes. The comparison of natural frequency is also demonstrated for full reservoir and empty reservoir cases.

An arbitrary Lagrangian-Eulerian method for nonlinear structural-acoustic interaction of hyperelastic solid and compressible viscous fluid

This paper develops a numerical method for predicting the nonlinear structural-acoustic interactions of a hyperelastic solid immersed in an unbounded compressible viscous fluid. The nonlinear acoustic wave model with perfectly matched layers adopted is proposed in an arbitrary Lagrangian-Eulerian frame to absorb acoustic waves at truncated fluid boundaries, whereas the geometric and material nonlinearities of the hyperelastic solid are characterized in a total Lagrangian form. Both the fluid and the solid are discretized by the finite element method, and both models are coupled together by the momentum equilibrium and kinematic compatibility on the common interface. The convergence and accuracy of the proposed method are assessed by comparing the computed results with existing solutions. A hyperelastic ring in a viscous fluid is analyzed to provide physical insights into the nonlinear dynamics behaviors of the coupled hyperelastic solid and acoustic fluid system. The hyperelastic ring in acoustic fluid exhibits deformation instability under a uniform distributed excitation load, producing a series of subharmonics, ultrasubharmonics, and superharmonics in the structural and acoustic responses. Nonlinear internal resonance and bifurcation phenomena in the vibration of the ring and the acoustic waves of the fluid are also discussed.

Novel Design Scheme for Structural Fundamental Frequency of Porous Acoustic Metamaterials

Structural resonance increases the vibration and noise of porous acoustic metamaterials while reducing the energy consumption and conversion efficiency of acoustic waves. Therefore, structural fundamental frequency of porous acoustic metamaterials is required to be controlled to avoid resonance. This study proposes a full-cycle interactive progressive (FIP) design scheme for porous acoustic metamaterials. The FIP design scheme first establishes a specific parameter relationship for the initial model based on the intentions of the designers. The initial model is then dynamically adjusted through a series of optimization processes. In particular, the FIP design scheme is developed for a porous acoustic metamaterial in an acoustic-structure interaction system. The effects of the structural parameters and applied boundary conditions of the porous acoustic metamaterial on the structural fundamental frequency are investigated. A surrogate model is introduced to reduce the calculation costs and improve the design efficiency of the parametric optimization. The frequency-modulation acoustic metamaterial is tailored to improve its acoustic and vibrational characteristics, including the resonance resistance and low dynamic response. The features of the FIP design scheme in the optimized design of porous acoustic metamaterials are demonstrated.

Analysis of ultrasonic partial discharge characteristics of GIS’s reducing unit based on Finite Element Method

GIS’s reducing unit is a new and environment-friendly structural unit, which can greatly reduce the consumption of aluminum alloy material and insulating gas. The structural size of this unit is much smaller than the conventional one. In this paper, an acoustic-structure coupling interaction model of partial discharge in reducing unit of gas insulated switchgear (GIS) is presented. The interaction between the internal acoustic source of partial discharge and structure of GIS is simulated with the finite element analysis, and the acoustic pressure levels distribution of GIS is obtained. The results show that the sound pressure distribution of the reducing unit is basically the same as that of the conventional one, but the amplitude is larger. At the same time, the high-frequency part of the acoustic signal attenuates more quickly in the reducing unit. This paper provides a theoretical guidance basis for the ultrasonic partial discharge detection of the GIS reducing unit.

Validation using the in vivo experiment of the 3D model of the human ear using the equivalent mechanical impedance of the Mass-Spring-Damper System

The ear can be defined as the organ responsible for auditory perception. Its role among others is to amplify, transmit and convert an acoustic wave, presents in the environment, into an electrical pulse that can be interpreted by the brain via the auditory nerve. The conductive hearing loss is a major public health problem; it is related to a malfunction of the outer or middle ear leading to an interruption of the propagation of the sound wave within the hearing organ. Conductive deafness is caused by impulse noise which is present in a large number of professional sectors; many professions and/or sectors of activity are therefore concerned. There are two primary aims of this study: (1) to realize a 3D model of the human ear in order to characterize the impulse noise and evaluate its auditory risks in professional environments so as to identify the means of protecting the ear; (2) to carry out a comparison between the results obtained numerically using our 3D model and those obtained from experimental tests. The 3D model of the human ear was realized using the COMSOL multiphysics software. The structure–acoustic interaction between the auditory canal, which will be considered as the propagation field of the acoustic wave, and the structures of the ear (eardrum, skin, bone, cartilage) have been solved using the Finite Element Method (FEM). For the modeling, the ossicles, the cochlea and the middle ear were replaced by a Mass-Spring-Damper System (MSDS). The results obtained from the 3D modeling show that the maximum displacements of the eardrum are in the frequency range of [1700, 2600] Hz. A peak on the sound pressure gain results around 3000 Hz was observed. The change in the damping coefficient d has a strong influence on the displacement of the eardrum. A grow of the acoustic pressure honest the eardrum compared to that recorded at the entrance of the auditory canal is noted. These results were validated by the results of experiments carried out in vivo.

Bi-material topology optimization for fully coupled structural-acoustic systems with isogeometric FEM–BEM

This paper presents a novel method for topology optimization of vibrating structures interacted with acoustic wave for the purpose of minimizing radiated sound power level. We consider exterior acoustic fields and bi-material shell models without damping in this work. Within the isogeometric analysis framework, we employ Catmull–Clark subdivision surfaces to construct geometries and discretize physical fields. The isogeometric finite element method with Kirchhoff–Love shell elements is coupled with the isogeometric boundary element method in acoustics. The topology optimization is performed through density-based approaches, in which the sensitivities are evaluated with adjoint variable methods. Numerical experiments demonstrate the validity and effectiveness of the algorithm for topology optimization of structural-acoustic interaction systems.

Nonlinear Behavior of Helmholtz Resonator With a Compliant Wall for Low-Frequency, Broadband Noise Control

Abstract Low-frequency sound attenuation is often pursued using Helmholtz resonators (HRs). The introduction of a compliant wall around the acoustic cavity results in a two degrees-of-freedom (2DOF) system capable of more broadband sound absorption. In this study, we report the amplitude-dependent dynamic response of a compliant-walled HR and investigate the effectiveness of wall compliance to improve the absorption of sound in linear and nonlinear regimes. The acoustic-structure interactions between the conventional HR and the compliant wall result in non-intuitive responses when acted on by nonlinear amplitudes of excitation pressure. This paper formulates and studies a reduced order model to characterize the nonlinear dynamic response of the 2DOF HR with a compliant wall compared to that of a conventional rigid HR. Validated by experimental evidence, the modeling framework facilitates an investigation of strategies to achieve broadband sound attenuation, including by selection of wall material, wall thickness, geometry of the HR, and other parameters readily tuned by system design. The results open up new avenues for the development of efficient acoustic resonators exploiting the deflection of a compliant wall for suppression of extreme noise amplitudes.

Shape optimization in acoustic–structure interaction

PurposeMotivated by the acoustics of motor vehicles, a coupled fluid–solid system is considered. The air pressure is modeled by the Helmholtz equation, and the structure displacement is described by elastodynamic equations. The acoustic–structure interaction is modeled by coupling conditions on the common interface. First, the existence and uniqueness of solutions are investigated, and then, after recalling fundamental notions of shape optimization, the tensor form of the distributed shape derivative is obtained for the coupled problem. It is then applied to the minimization of the sound pressure by variation of the structure shape through the positioning of beads.Design/methodology/approachThe existence and uniqueness of solutions up to eigenfrequencies are shown by the Fredholm–Riesz–Schauder theory using a novel decomposition into an isomorphism and a compact operator. For the design optimization, the distributed shape derivative is obtained using the averaged adjoint method. It is then used in a closed 3D optimization process of the position of a bead for noise reduction. In this process, the C++ library concepts are used to solve the differential equations on hexahedral meshes with the finite element method of higher order.FindingsThe existence and uniqueness of solutions have been shown for the case without absorption, where the given proof allows for extension to the case with absorption in the domain or via boundary conditions. The theoretical results show that the averaged adjoint can be applied to compute distributed shape derivatives in the context of acoustic–structure interaction. The numerical results show that the distributed shape derivative can be used to reduce the sound pressure at a chosen frequency via rigid motions of a nonsmooth shape.Originality/valueThe proof of shape differentiability and the calculation of the distributed shape derivative in tensor form allows to consider nonsmooth shapes for the optimization, which is particularly relevant for the optimal placement of beads or stampings in a structural-acoustic system.