Vibration and Sound Radiation of Sandwich Beams With Honeycomb Truss Core

2003 ◽  
Author(s):  
M. Ruzzene
Keyword(s):  
Acoustic Radiation ◽  
Sound Radiation ◽  
Structural Response ◽  
Element Model ◽  
Frame Structure ◽  
Sandwich Beams ◽  
The Core ◽  
Truss Core ◽  
Vibration And Sound Radiation ◽  
Spectral Finite Element

The vibrations of and the sound radiation from sandwich beams with truss core are here analyzed. The structure of the core is composed of a sequence of identical unit cells repeating along the beam length and across the core thickness. Each cell is composed of beam elements assembled to form a frame structure. Layouts with honeycomb patterns arranged through the thickness of the core are considered. This design represents an alternative with respect to the traditional application of honeycombs in sandwich construction. The proposed configuration provides sandwich beams with interesting structural as well as acoustic characteristics. A spectral finite element model is developed to evaluate the structural and the acoustic behavior of the considered class of sandwich beams. The spectral model can be easily coupled with a Fourier Transform based analysis of the sound radiated by the fluidloaded structure. The model predicts the performance of beams with various core configurations. The comparison is carried out in terms of vibration and sound radiation in an unbounded acoustic half-plane. Hexagonal and re-entrant honeycomb configurations are considered to study the effects of core geometry on structural response and acoustic radiation.

Vibration and Sound Radiation of Truss Core Panels

2007 ◽  
Vol 334-335 ◽  
pp. 969-972
Author(s):  
Jian Ren ◽  
C.H. Deng ◽  
Q.Z. Hou
Keyword(s):  
Sound Radiation ◽  
Element Model ◽  
Spectral Element ◽  
Acoustic Medium ◽  
Distributed Parameter ◽  
Truss Core ◽  
Transmission Reduction ◽  
Vibration And Sound Radiation ◽  
The Fourier Transform ◽  
Reduction Index

The dynamic response and the sound radiation of truss core panels are investigated in this paper. The spectral element model for the truss core panel is developed. The element model is established by employing shape functions derived directly from the solution of distributed parameter models for each beam element. Forced vibrations of a fluid-loaded beam in a rigid baffle are considered. The spectral formulation can be easily and efficiently coupled with the Fourier transform (FT) based analysis of the structure’s sound radiation in a surrounding acoustic medium. Hence the proposed formulation is an efficient numerical tool for the analysis of the dynamic and acoustic performance of the considered truss core sandwich panels. The comparison of the sound characteristics selected as sound transmission reduction index to the psychical parameters of the truss core beam is carried out.

Active Control of Vibration and Noise Radiation from Fluid-Loaded Cylinder using Active Constrained Layer Damping

2002 ◽  
Vol 8 (6) ◽  
pp. 877-902 ◽  
Author(s):  
W. Laplante ◽  
T. Chen ◽  
A. Baz ◽  
W. Sheilds
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Acoustic Radiation ◽  
Sound Radiation ◽  
Element Model ◽  
Water Tank ◽  
Constrained Layer Damping ◽  
Active Constrained Layer Damping ◽  
Active Constrained Layer ◽  
Surrounding Fluid

Vibration and sound radiation from fluid-loaded cylindrical shells are controlled using patches of Active Constrained Layer Damping (ACLD). The performance and the enhanced damping characteristics via reduced vibrations and sound radiation in the surrounding fluid is demonstrated both theoretically and experimentally. A prime motivation for this work is the potential wide applications in submarines and torpedoes where acoustic stealth is critical to the effectiveness of missions. A finite element model is also developed to predict the vibration and the acoustic radiation in the surrounding fluid of the ACLD-treated cylinders. The developed model is used to study the effectiveness of the control and placement strategies of the ACLD in controlling the fluid-structure interactions. A water tank is constructed that incorporates test cylinders treated with two ACLD patches placed for targeting specific vibration modes. Using this arrangement, the effectiveness of different control strategies is studied when the submerged cylinders are subjected to internal excitation, and the radiated sound pressure level in the water is observed. Comparisons are made between the experimental results and the theoretical predictions to validate the finite element model.

Buckling of sandwich panels with transversely flexible core: Correction of the equivalent single-layer model using thick-faces effect

2018 ◽  
Vol 22 (5) ◽  
pp. 1612-1634 ◽  
Author(s):  
J Jelovica ◽  
J Romanoff
Keyword(s):  
Finite Element ◽  
Transverse Shear ◽  
Sandwich Panels ◽  
Shear Deformation Theory ◽  
Single Layer ◽  
Element Model ◽  
Layer Model ◽  
The Core ◽  
Truss Core ◽  
Single Layer Model

Modeling a periodic structure as a homogeneous continuum allows for an effective structural analysis. This approach represents a sandwich panel as a two-dimensional plate of equivalent stiffness. Known as the equivalent single-layer, the method is used here to analyze bifurcation buckling of three types of sandwich panels with unidirectional stiffeners in the core: truss-core, web-core and corrugated-core panels made of an isotropic material. The transverse shear stiffnesses of these panels can differ by several orders of magnitude, which cause incorrect buckling analysis when using the equivalent single-layer model with the first-order shear deformation theory. Analytical solution of the problem predicts critical buckling loads that feature infinite number of half-waves in the direction perpendicular to the stiffeners. Finite element model also predicts buckling modes that have non-physical, saw-tooth shape with infinite curvature at nodes. However, such unrealistic behavior is not observed when using detailed three-dimensional finite element models. The error in the prediction of the critical buckling load is up to 85% for the cases considered here. The correction of the equivalent single-layer model is proposed by modeling the thick-faces effect to ensure finite curvature. This is performed in the finite element setting by introducing an additional plate with tied deflections to the equivalent single-layer plate. The extra plate is represented with bending and transverse shear stiffness of the face plates. As a result, global buckling is predicted accurately. Guidelines are proposed to identify the sandwich panels where ordinary model is incorrect. Truss-core and web-core sandwich panels need the correction. Corrugated-core panels without a gap between plates in the core have smaller shear orthotropy and do not need the correction. Modeling the thick-faces effect ensures correct results for all cases considered in this study, and thus one should resort to this approach in case of uncertainty whether the ordinary equivalent single-layer model is valid.

Vibrational and acoustic radiation from a submerged periodic cylindrical shell with axial stiffening

2009 ◽  
Vol 223 (5) ◽  
pp. 1083-1089 ◽  
Author(s):  
C-J Liao ◽  
W-K Jiang ◽  
H Duan ◽  
Y Wang
Keyword(s):  
Cylindrical Shell ◽  
Analytical Study ◽  
Acoustic Radiation ◽  
Sound Radiation ◽  
Mechanical Impedance ◽  
Stiffened Cylindrical Shell ◽  
Reaction Forces ◽  
Radial Forces ◽  
Vibration And Sound Radiation ◽  
Finite Cylindrical Shell

An analytical study on the vibration and acoustic radiation from an axially stiffened cylindrical shell in water is presented. Supposing that the axial stiffeners interact with the cylindrical shell only through radial forces, the reaction forces on the shell from stiffeners can be expressed by additional impedance. The coupled vibration equation of the finite cylindrical shell with axial stiffening is derived; in this equation additional impedance caused by the axial stiffeners is added. As a result, the vibration and sound radiation of the shell are dependent on the mechanical impedance of the shell, the radiation sound impedance, and the additional impedance of the axial stiffeners. Based on the numerical simulation, it is found that the existence of axial stiffeners decreases the sound radiation and surface average velocity, whereas it increases the radiation factor. The characteristics of the acoustic radiation can be understood from the simulation with good results, which show that the presented methodology can be used to study the mechanism of the acoustic radiation of the complicated cylindrical shell and to optimize its design.

Vibration and Sound Radiation Characteristics of Composite Flat-Panel Sound Radiator

2013 ◽  
Vol 431 ◽  
pp. 177-181
Author(s):  
C.H. Jiang ◽  
T.Y. Kam
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Response Spectrum ◽  
Sound Radiation ◽  
Laminated Composite ◽  
Element Model ◽  
Flat Panel ◽  
Radiation Characteristics ◽  
Experimental Approaches ◽  
Vibration And Sound Radiation

The vibration and sound radiation characteristics of laminated composite flat-panel sound radiators are studied via both theoretical and experimental approaches. In the theoretical study, a finite element model is presented to formulate the forced vibration of the sound radiators. The first Rayleigh integral is used to construct the sound pressure level curve of the sound radiators. In the experimental study, a laminated composite sound radiator was subjected to sweep sine excitation to determine the frequency response spectrum from which the natural frequencies of the sound radiator were identified. The sound radiator with salt powder distributed on its top surface was excited to generate the vibration shapes of the sound radiator at several selected frequencies. The SPL curve of the sound radiator was also measured experimentally. The experimental results are then used to verify the feasibility and accuracy of the proposed finite element model.

Research on Vibration and Sound Radiation from Submarine Functionally Graded Material Nonpressure Cylindrical Shell

2013 ◽  
Vol 690-693 ◽  
pp. 3046-3049
Author(s):  
Yan Bing Zhang ◽  
Chun Yu Ren ◽  
Xi Zhu
Keyword(s):  
Cylindrical Shell ◽  
Acoustic Radiation ◽  
Radiation Power ◽  
Sound Radiation ◽  
Functionally Graded ◽  
Underwater Sound ◽  
Graded Materials ◽  
Graded Material ◽  
Vibration And Sound Radiation ◽  
Sound Radiation Power

In this paper, we establish the finite element (FEM) and boundary element (BEM) models of a submarine section, and study the underwater sound radiation field of three different non-pressure shells made of steel, steel with anechoic tile, and the functionally graded materials (FGM) separately using a method combining of FEM and BEM . Research shows that the combination of FEM and BEM can address the acoustic radiation calculation problem of FGM, and in comparison with steel and anechoic tile laying submarine section, the weight of FGM non-pressure shell reduces 1600kg, and the sound radiation power decreases 4db and 2.5db respectively, thus having better performance in vibration and noise reduction.

Simulation of Vibration and Acoustic Radiation of Finite Underwater Cylindrical Shells

2000 ◽  
Author(s):  
X. M. Zhang ◽  
G. R. Liu ◽  
K. Y. Lam
Keyword(s):  
Acoustic Analysis ◽  
Acoustic Radiation ◽  
Cylindrical Shells ◽  
Sound Radiation ◽  
Coupled Vibration ◽  
Response Curves ◽  
Vibration And Sound Radiation ◽  
Acoustic Domain ◽  
High Sound ◽  
Element Method

Abstract A coupled structural-acoustic analysis of vibration and sound radiation of underwater finite cylindrical shells is investigated in this paper. The coupled vibration and radiation problem is formulated using Finite Element Method (FEM) for the structure and Boundary Element Method (BEM) for the acoustic domain. Vibration and sound radiation under symmetrical and unsymmetrical point force excitations are examined. It is shown that the coupled modals are the causes of large vibration of the shell and high sound pressure radiation of the acoustic fields. The shapes of frequency response curves of pressure are quite similar in the far fields but change greatly in the near fields.

Stress Impact Analysis of Steel Frame with Different Beam-Column Connection Mode

2013 ◽  
Vol 275-277 ◽  
pp. 1028-1033
Author(s):  
Gang Wang
Keyword(s):  
Impact Analysis ◽  
Structural Response ◽  
Time History ◽  
Horizontal Displacement ◽  
Element Model ◽  
Steel Frame ◽  
Frame Structure ◽  
Natural Period ◽  
Vibration Period ◽  
Steel Frame Structure

This paper uses the SAP2000 to establish different beam column connections of steel frame structure finite element model, comparative analysis of the beam column for the rigid connection, hinged, semi-rigid connections of steel frame structure, the dynamic characteristics of structure displacement and internal force influence. At the same time, the dynamic time-history analysis method for structural displacement supplementary checking, analysis of structural response to seismic wave degree．The results showed that：compared with rigid, the structure of semi-rigid connections to the larger natural period，and with the rotation stiffness decreases vibration period increases; Semi-rigid steel frame connection to reduce the resistance to push the layer stiffness，making the structure of the horizontal displacement increased．

Sign in / Sign up

Export Citation Format

Share Document