• 제목/요약/키워드: vibroacoustic

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진동-음향 연성계의 구조-유체 상호작용 (Structure-Fluid Interaction in a Coupled Vibroacoustic System)

  • 최성훈;김진오
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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    • pp.135-141
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    • 1996
  • Numerical analysis techniques have been applied to obtain the vibroacoustic characteristics of the simplified model of a passenger-car cabin. Two kinds of coupled vibration-acoustic analysis, such as one-way coupling and full coupling, have been carried out via the interface between the results of vibration analysis by FEM and acoustic analysis by BEM. The comparison of two coupled analysis results show the fluid-structure interaction in terms of the coupled effect of the vibration and noise.

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음악과 음향진동자극에 의한 인체에의 영향 (The Effect on Human Body by the Stimuli of Musics and Acoustic Vibrations)

  • 문덕홍
    • 동력기계공학회지
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    • 제12권5호
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    • pp.59-64
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    • 2008
  • 이 연구는 음악과 음향진동자극이 인체의 생리적 변화 즉 특정 뇌파발생의 유도에 미치는 영향을 실험적으로 고찰한 결과 다음과 같이 요약할 수 있다. 1. 음악자극만의 경우보다 음향진동자극을 동시에 가하였을 경우가 특정뇌파상태로의 유도가 용이하고 현저하였다. 2. 자극2와 자극5의 자극에 사용된 음악은 이완작용 및 스트레스해소에 적합한 음악이다. 3. 자극6의 음악은 스트레스가 없고 정신집중상태에서 많이 발생하는 SMR파의 유도에 효과가 있을 것으로 생각된다.

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통계적 에너지 해석을 이용한 RazakSAT 의 음향진동 연성해석 (Vibroacoustic Analysis of RazakSAT using SEA)

  • 강명석;배정석;김종운;최웅;우성현;김영기
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2005년도 춘계학술대회논문집
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    • pp.953-956
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    • 2005
  • The vibroacoustic analysis has been carried out on the RazakSAT qualification model which was developed by SI and ATSB. Statistical energy analysis was used for the analysis and the results was compared with acoustic test results. The equipments of the RazakSAT are simplified as uniformly distributed mass on the panels in the SEA model. According to the comparison of the analysis and test results, SEA is useful estimation of the response in high frequency region and the results are valid when the assumption of equipartition of modal energy is agreed.

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A hybrid algorithm of underwater structure vibration and acoustic radiation-propagation in ocean acoustic channel

  • Duan, Jia-xi;Zhang, Lin;Da, Liang-long;Sun, Xue-hai;Chen, Wen-jing
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제12권1호
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    • pp.680-690
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    • 2020
  • In ocean environment, the sound speed gradient of seawater has an important influence on far field sound propagation. The FEM/BEM is used to decouple the vibroacoustic radiation of the spherical shell, and the Green function of the virtual source chain is adopted for decoupling. For far field radiated Sound Pressure Level (SPL), the Beam Displacement Ray normal Mode (BDRM) is employed. The vibration and near-/far-field radiated SPL of spherical shell is analyzed in shallow sea uniform layer, negative/positive gradient, negative thermocline environment, and deep-sea sound channel. Results show that the vibroacoustic radiation of spherical shell acted at 300Hz can be analogous to dipole. When the radiated field of the spherical shell is dominated by large-grazing-angle waves, it can be analogous to vertically distributed dipole, and the far field radiated SPL is lower; while similar to horizontally distributed dipole if dominated by small-grazing-angle waves, and the far field SPL is high.

Assessment of statistical sampling methods and approximation models applied to aeroacoustic and vibroacoustic problems

  • Biedermann, Till M.;Reich, Marius;Kameier, Frank;Adam, Mario;Paschereit, C.O.
    • Advances in aircraft and spacecraft science
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    • 제6권6호
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    • pp.529-550
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    • 2019
  • The effect of multiple process parameters on a set of continuous response variables is, especially in experimental designs, difficult and intricate to determine. Due to the complexity in aeroacoustic and vibroacoustic studies, the often-performed simple one-factor-at-a-time method turns out to be the least effective approach. In contrast, the statistical Design of Experiments is a technique used with the objective to maximize the obtained information while keeping the experimental effort at a minimum. The presented work aims at giving insights on Design of Experiments applied to aeroacoustic and vibroacoustic problems while comparing different experimental designs and approximation models. For this purpose, an experimental rig of a ducted low-pressure fan is developed that allows gathering data of both, aerodynamic and aeroacoustic nature while analysing three independent process parameters. The experimental designs used to sample the design space are a Central Composite design and a Box-Behnken design, both used to model a response surface regression, and Latin Hypercube sampling to model an Artificial Neural network. The results indicate that Latin Hypercube sampling extracts information that is more diverse and, in combination with an Artificial Neural network, outperforms the quadratic response surface regressions. It is shown that the Latin Hypercube sampling, initially developed for computer-aided experiments, can also be used as an experimental design. To further increase the benefit of the presented approach, spectral information of every experimental test point is extracted and Artificial Neural networks are chosen for modelling the spectral information since they show to be the most universal approximators.

Vibroacoustic analysis of stiffened functionally graded panels in thermal environments

  • Ashish K. Singh;Anwesha Pal;Shashi Kumar;Anuja Roy;Atanu Sahu
    • Structural Engineering and Mechanics
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    • 제89권5호
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    • pp.437-452
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    • 2024
  • Functionally graded materials (FGMs) have gained substantial attention from researchers due to their exceptional strength and thermal resistance. Their utilization in the aviation and automobile industries has significantly improved the efficiency of various structural components. Moreover, stiffened panels find wide applications in aerospace and automobile structures and these panels are frequently exposed to extreme environments. It is from this perspective that our research is focused on analysing the vibroacoustic response of stiffened functionally graded panels subjected to external dynamic excitations in a thermal environment. In the present research work, a finite element model is developed to conduct the dynamic analysis of functionally graded stiffened panels using the first-order shear deformation theory. Subsequently, a boundary element based model is also developed and coupled with the finite element model to investigate the sound radiation behaviour of those panels in a thermal environment. The material properties of FG stiffened panels are considered as temperature dependent, while the thermal environment is assumed to be acting as linearly varying through the panel's thickness. The present investigation aim to compare the vibroacoustic responses of different panels due to stiffener orientations, material compositions, power law indices and plate thicknesses at various temperatures. The research findings highlight the significant impact of addition of stiffeners, its orientation and material compositions on the sound radiation characteristics of these panels under thermal environments. The present numerical model can easily be employed for analysing the sound radiation behaviour of other types of flat or curved stiffened panels having arbitrary geometry and boundary conditions.

FEM vibroacoustic analysis in the cabin of a regional turboprop aircraft

  • Cinefra, Maria;Passabi, Sebastiano;Carrera, Erasmo
    • Advances in aircraft and spacecraft science
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    • 제5권4호
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    • pp.477-498
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    • 2018
  • The main goal of this article is to validate a methodological process in Actran MSC Software, that is based on the Finite Element Method, to evaluate the comfort in the cabin of a regional aircraft and to study the noise and vibrations reduction through the fuselage by the use of innovative materials. In the preliminary work phase, the CAD model of a fuselage section was created representing the typical features and dimensions of an airplane for regional flights. Subsequently, this model has been imported in Actran and the Sound Pressure Level (SPL) inside the cabin has been analyzed; moreover, the noise reduction through the fuselage has been evaluated. An important investigation and data collection has been carried out for the study of the aircraft cabin to make it as close as possible to a real problem, both in geometry and in materials. The mesh of the structure has been built from the CAD model and has been simplified in order to reduce the number of degrees of freedom. Finally, different fuselage configurations in terms of materials are compared: in particular, aluminum, composite and sandwich material with composite skins and poroelastic core are considered.

반응표면법을 이용한 진동-음향 연성계의 흡음재 최적배치 (Optimum Allocation of Sound Absorbing Materials in a Vibroacoustic System using Response Surface Methodology)

  • 홍도관;백황순;우병철;안찬우
    • 한국정밀공학회지
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    • 제28권10호
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    • pp.1196-1203
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    • 2011
  • Statistical optimum methodology of table of orthogonal array, ANOM, ANOVA and RSM are applied to formulate optimum allocation design with design variables. It can be minimized average SPL of control volume, the objective function in closed system by optimal allocated positions of absorbing material. Structural natural frequency and acoustic natural frequency of cavity are analyzed by FEM and BEM in the closed system. Using BEM, average SPL of specific control volume is calculated according to the condition before using absorbing material and after using it. It is shown that noise is reduced by $5.02dB_{RMS}$ by absorbing material located at optimal position and minimum $1.83dB_{RMS}$ and maximum $3.47dB_{RMS}$ by the table of orthogonal array.

Hygrothermal sound radiation analysis of layered composite plate using HFEM-IBEM micromechanical model and experimental validation

  • Binita Dash;Trupti R Mahapatra;Punyapriya Mishra;Debadutta Mishra
    • Structural Engineering and Mechanics
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    • 제89권3호
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    • pp.265-281
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    • 2024
  • The sound radiation responses of multi-layer composite plates subjected to harmonic mechanical excitation in hygrothermal environment is numerically investigated. A homogenized micromechanical finite element (FE) based on the higher-order mid-plane kinematics replicating quadratic function as well as the through the thickness stretching effect together with the indirect boundary element (IBE) scheme has been first time employed. The isoparametric Lagrangian element (ten degrees of freedom per node) is used for discretization to attain the hygro-thermo-elastic natural frequencies and the modes of the plate via Hamilton's principle. The effective material properties under combined hygrothermal loading are considered via a micromechanical model. An IBE method is then implemented to attain structure-surrounding coupling and the Helmholtz wave equation is solved to compute the sound radiation responses. The effectiveness of the model is tested by converging it with the similar analytical/numerical results as well as the experimentally acquired data. The present scheme is further hold out for solving diverse numerical illustrations. The results revealed the relevance of the current higher-order FE-IBE micromechanical model in realistic estimation of hygro-thermo-acoustic responses. The geometrical parameters, volume fraction of fiber, layup, and support conditions alongside the hygrothermal load is found to have significant influence on the vibroacoustic characteristics.

Prediction of Fluid-borne Noise Transmission Using AcuSolve and OptiStruct

  • Barton, Michael;Corson, David;Mandal, Dilip;Han, Kyeong-Hee
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2014년도 추계학술대회 논문집
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    • pp.557-561
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    • 2014
  • In this work, Altair Engineering's vibroacoustic modeling approach is used to simulate the acoustic signature of a simplified automobile in a wind tunnel. The modeling approach relies on a two step procedure involving simulation and extraction of acoustic sources using a high fidelity Computational Fluid Dynamics (CFD) simulation followed by propagation of the acoustic energy within the structure and passenger compartment using a structural dynamics solver. The tools necessary to complete this process are contained within Altair's HyperWorks CAE software suite. The CFD simulations are performed using AcuSolve and the structural simulations are performed using OptiStruct. This vibroacoustics simulation methodology relies on calculation of the acoustic sources from the flow solution computed by AcuSolve. The sources are based on Lighthill's analogy and are sampled directly on the acoustic mesh. Once the acoustic sources have been computed, they are transformed into the frequency domain using a Fast Fourier Transform (FFT) with advanced sampling and are subsequently used in the structural acoustics model. Although this approach does require the CFD solver to have knowledge of the acoustic simulation domain a priori, it avoids modeling errors introduced by evaluation of the acoustic source terms using dissimilar meshes and numerical methods. The aforementioned modeling approach is demonstrated on the Hyundai Simplified Model (HSM) geometry in this work. This geometry contains flow features that are representative of the dominant noise sources in a typical automobile design; namely vortex shedding from the passenger compartment A-pillar and bluff body shedding from the side view mirrors. The geometry also contains a thick poroelastic material on the interior that acts to reduce the acoustic noise. This material is modeled using a Biot material formulation during the structural acoustic simulation. Successful prediction of the acoustic noise within the HSM geometry serves to validate the vibroacoustic modeling approach for automotive applications.

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