Influence of Wall Surface and Air Modelling in Finite-Element Analysis of Sound Transmission Between Rooms in Lightweight Buildings

2012 ◽  
Author(s):  
Lars Vabbersgaard Andersen ◽  
Poul Henning Kirkegaard ◽  
Kristoffer Ahrens Dickow ◽  
Nikolaj Kiel ◽  
Kent Persson
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Acoustic Field ◽  
Degrees Of Freedom ◽  
Sound Pressure ◽  
Numerical Approach ◽  
Element Analysis ◽  
Low Frequencies ◽  
Infinite Elements ◽  
Rigorous Model

Noise is a nuisance in the built environment, and to avoid undesirable transmission of sound and vibration within a building, its vibro-acoustic performance must be addressed in the design phase. For heavy structures, a reliable assessment of the sound pressure levels can be made by statistical energy analysis—especially at high frequencies. However, for lightweight buildings a numerical approach, e.g. the finite-element method, must be applied. A problem in this regard is the computational complexity. Even at low frequencies, many degrees of freedom are required in a model accounting for all possible paths for transmission of sound in a building—in particular when finite elements are employed for the air. This paper examines whether a rigorous model of the acoustic field in each room is necessary in order to obtain accurate estimates of the sound pressure, or if a simpler approach may be adopted. Five different cases are compared: A model that only includes the structure, a model with semi-infinite elements to account for radiation from the structure into the air, a model introducing finite elements for the acoustic field, a model with dissipation of sound inside the room, and finally a model with sound absorption on the surfaces of walls, floors and ceilings.

The Application of Harmonic Finite Elements in the Seismic Response Spectrum Analysis of a Skirt Supported Vessel

2010 ◽  
Author(s):  
Bikramjit Singh Antaal ◽  
Yogeshwar Hari ◽  
Dennis K. Williams
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Seismic Response ◽  
Spectrum Analysis ◽  
Degrees Of Freedom ◽  
Response Spectrum ◽  
Response Spectrum Analysis ◽  
Element Analysis ◽  
Structure Interaction ◽  
Input Response

This paper describes the finite element considerations employed in a seismic response spectrum analysis of a skirt supported, liquid containing pressure vessel. Like many axisymmetric cylindrical vessels, the gross seismic response to an input response spectrum can be categorized by a simplified lump mass model that includes both the mass of the vessel proper in combination with the associated mass of multiple fluid levels. This simplified response may be utilized to determine the initial sizing of the supporting configuration, such as a skirt, but lacks the ability to properly address the fluid-structure interaction that creates sloshing loads on the vessel walls. The most obvious method to address the fluid-structure interaction when considering the finite element method is to build a three-dimensional model of the vessel proper, including, but not limited to the shell courses, the top and bottom heads (for a vertical vessel), and the support skirt. The inclusion of the fluid effects may now be incorporated with a “contained fluid” finite element, however, for vessels of any significant volume, the number of finite elements can easily exceed 100,000 and the number of degrees of freedom can sore from as few as 300,000 to as many as 500,000 or more. While these types of finite element analysis problems can be solved with today’s computer hardware and software, it is not desirable in any analysis to have that volume of information that has to be reviewed and approved in a highly regulated nuclear QA environment (if at all possible). With these items in mind, the methodology described in this paper seeks to minimize the number of degrees of freedom associated with a response spectrum analysis of a liquid filled, skirt supported vertical pressure vessel. The input response spectra are almost always provided in Cartesian coordinates, while many, if not most liquid containing pressure vessels are almost always axisymmetric in geometry without having benefit of being subjected to an axisymmetric load (acceleration in this case) due to the specified seismic event. The use of harmonic finite elements for both the vessel structure and the contained fluid medium permit the efficiencies associated with an axisymmetric geometry to be leveraged when the seismic response spectrum is formulated in terms of a Fourier series and combined to regain the effects of the two orthogonal, horizontally applied accelerations as a function of frequency. The end result as discussed and shown in this paper is a finite element model that permits a dense mesh of both the fluid and the structure, while economizing on the number of simultaneous equations required to be solved by the chosen finite element analysis.

scholarly journals Finite elements with continuous stress fields in calculation of folded prismatic thin-walled rods and shells

2018 ◽  
Vol 196 ◽  
pp. 01018
Author(s):  
Sergey Nazarenko ◽  
Nina Blokhina
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
Stress Fields ◽  
Displacement Fields ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Shell Finite Element ◽  
Rectangular Shell

The article deals with methods of creating a rectangular wall-beam finite element with eight degrees of freedom per node and continuous stress fields along the boundaries. This effect is achieved by specifying displacement fields in the plane of the element in forms similar to those in finite elements of Bogner, Fox, and Schmitt plate. The article provides algebraic expressions for displacement forms; methods of forming reaction and stress matrices are also considered. Test calculations carried out with the help of “Computational mechanics” FEM complex have proved high efficiency of the finite element analysis performed. A rectangular shell finite element with twelve degrees of freedom per node was developed as a combination of membrane finite element and Bogner, Fox and Schmitt plate element.

Implementation of Fourier Series in the Seismic Response Spectrum Analysis of Ground Supported Tanks

2010 ◽  
Author(s):  
Bikramjit Singh Antaal ◽  
Yogeshwar Hari ◽  
Dennis K. Williams
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Seismic Response ◽  
Spectrum Analysis ◽  
Degrees Of Freedom ◽  
Response Spectrum ◽  
Response Spectrum Analysis ◽  
Element Analysis ◽  
Structure Interaction ◽  
Input Response

This paper describes the finite element considerations employed in a seismic response spectrum analysis of a ground supported, liquid containing tank. Like many axisymmetric cylindrical vessels, the gross seismic response to an input response spectrum can be categorized by a simplified lumped mass model that includes both the mass of the tank proper in combination with the associated mass of multiple fluid levels. This simplified response may be utilized to determine the initial sizing of the supporting configuration, but lacks the ability to properly address the fluid-structure interaction that creates sloshing loads on the tank walls. The most obvious method to address the fluid-structure interaction when considering the finite element method is to build a three-dimensional model of the tank, including, but not limited to the shell courses, the top and bottom heads (for a vertical vessel), and any tank supports. The inclusion of the fluid effects may now be incorporated with “contained fluid” finite elements, however, for tanks of any significant volume, the number of finite elements can easily exceed 100,000 and the number of degrees of freedom can sore from as few as 300,000 to as many as 500,000 or more. While these types of finite element analysis problems can be solved with today’s computer hardware and software, it is not desirable in any analysis to have that volume of information that has to be subjected to the nuclear QA environment (if at all possible). With these items in mind, the methodology described in this paper seeks to minimize the number of degrees of freedom associated with a response spectrum analysis of a liquid filled, vertical cylindrical tank. The input response spectra are almost always provided in Cartesian coordinates, while many, if not most liquid containing pressure tanks are almost always axisymmetric in geometry without having benefit of being subjected to an axisymmetric load (acceleration in this case) due to the specified seismic event. The use of harmonic finite elements for both the tank structure and the contained fluid medium permit the efficiencies associated with an axisymmetric geometry to be leveraged when the seismic response spectrum is formulated in terms of a Fourier series and combined to regain the effects of the two orthogonal, horizontally applied accelerations as a function of frequency. The end result as discussed and shown in this paper is a finite element model that permits a dense mesh of both the fluid and the structure, while economizing on the number of simultaneous equations required to be solved during the chosen finite element analysis.

Structural and Continuum Mechanics Approaches for a 3D Shear Deformable ANCF Beam Finite Element: Application to Buckling and Nonlinear Dynamic Examples

2013 ◽  
Vol 9 (1) ◽  
Author(s):  
Karin Nachbagauer ◽  
Johannes Gerstmayr
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Continuum Mechanics ◽  
Degrees Of Freedom ◽  
Mass Matrix ◽  
Finite Element Software ◽  
High Order Convergence ◽  
Dynamics Problems ◽  
Transverse Slope ◽  
Shear Deformable

For the modeling of large deformations in multibody dynamics problems, the absolute nodal coordinate formulation (ANCF) is advantageous since in general, the ANCF leads to a constant mass matrix. The proposed ANCF beam finite elements in this approach use the transverse slope vectors for the parameterization of the orientation of the cross section and do not employ an axial nodal slope vector. The geometric description, the degrees of freedom, and a continuum-mechanics-based and a structural-mechanics-based formulation for the elastic forces of the beam finite elements, as well as their usage in several static problems, have been presented in a previous work. A comparison to results provided in the literature to analytical solution and to the solution found by commercial finite element software shows accuracy and high order convergence in statics. The main subject of the present paper is to show the usability of the beam finite elements in dynamic and buckling applications.

Adaptive Degrees-of-Freedom Finite Element Analysis of 3-D Transient Magnetic Problems

2020 ◽  
pp. 1-1
Author(s):  
Yunpeng Zhang ◽  
Xinsheng Yang ◽  
Huihuan Wu ◽  
Dingguo Shao ◽  
Weinong Fu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
Element Analysis

scholarly journals Eliminating Underconstraint in Double Parallelogram Flexure Mechanisms

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Robert M. Panas ◽  
Jonathan B. Hopkins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Experimental Measurement ◽  
Degrees Of Freedom ◽  
Dynamic Performance ◽  
Average Error ◽  
Static Stiffness ◽  
Element Analysis ◽  
Linkage Design ◽  
Analytical Expressions

We present an improved flexure linkage design for removing underconstraint in a double parallelogram (DP) linear flexural mechanism. This new linkage alleviates many of the problems associated with current linkage design solutions such as static and dynamic performance losses and increased footprint. The improvements of the new linkage design will enable wider adoption of underconstraint eliminating (UE) linkages, especially in the design of linear flexural bearings. Comparisons are provided between the new linkage design and existing UE designs over a range of features including footprint, dynamics, and kinematics. A nested linkage design is shown through finite element analysis (FEA) and experimental measurement to work as predicted in selectively eliminating the underconstrained degrees-of-freedom (DOF) in DP linear flexure bearings. The improved bearing shows an 11 × gain in the resonance frequency and 134× gain in static stiffness of the underconstrained DOF, as designed. Analytical expressions are presented for designers to calculate the linear performance of the nested UE linkage (average error < 5%). The concept presented in this paper is extended to an analogous double-nested rotary flexure design.

Finite Element Quarter Vehicle Suspension Model under Periodic Bump and Sinusoidal Road Excitation

2018 ◽  
Vol 880 ◽  
pp. 163-170
Author(s):  
Ștefan Cristian Castravete ◽  
Gabriel Cătălin Marinescu ◽  
Nicolae Dumitru ◽  
Oana Victoria Oţăt
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Element Model ◽  
Finite Model ◽  
Vehicle Speed ◽  
Element Analysis ◽  
Car Suspension ◽  
The Finite Element Analysis ◽  
Road Excitation ◽  
Suspension Model

The paper studies the behavior of a quarter-car suspension model under periodic road excitation: sinusoidal and bump (trapezoidal shape) for a constant vehicle speed. A theoretical and a finite element model were developed. The theoretical model has two degrees of freedom and a modal and sinusoidal excitation was performed to compare with finite model analysis. The finite element analysis consists of three parts: preload, modal analysis and deterministic external excitation. The study consists of the analysis of forces, displacements and accelerations that are transmitted to the vehicle regarding their variation in time and frequency.

Design and Development of a New Right Arm Prosthetic Kit for a Racing Cyclist

2009 ◽  
Vol 33 (3) ◽  
pp. 284-291 ◽  
Author(s):  
Louis-Philippe Riel ◽  
Jérôme Adam-Côté ◽  
Stéphane Daviault ◽  
Christophe Salois ◽  
Julien Laplante-Laberge ◽  
...  
Keyword(s):  
Finite Element ◽  
Case Report ◽  
Degrees Of Freedom ◽  
Material Selection ◽  
Time Trial ◽  
New Right ◽  
Universal Joint ◽  
Element Analysis ◽  
Freedom Of Movement ◽  
World Class

This case report describes a newly developed prosthetic arm for a world class trans-humeral amputee cyclist. The proposed solution consists of a new prosthetic kit that was designed to meet requirements of weight, freedom of movement and precise positioning for the disciplines of time-trial, pursuit, road and team sprint. The kit is made of different attachments that can be changed depending on the event the athlete is competing in. The prosthesis is composed of an extended socket made of composite materials, an arm made of aluminum tubes, a universal joint for the junction with the handlebars and different attachments for each bicycle. The system's weight is kept to a minimum using finite element analysis and careful material selection. The universal joint provides the angular degrees of freedom required to allow the athlete to stand up while pedaling, a freedom of movement lost since amputation. In this case report, the athlete's needs are presented and followed by the design of the product using Finite Element modeling. Results are then presented and discussed. This prosthetic kit was used by the athlete for the 2008 Paralympics games in Beijing.

scholarly journals Spatial Finite Element Analysis for Dynamic Response of Curved Thin-Walled Box Girder Bridges

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yinhui Wang ◽  
Yidong Xu ◽  
Zheng Luo ◽  
Haijun Wu ◽  
Liangliang Yan
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Response Analysis ◽  
Box Girder Bridges ◽  
Element Analysis ◽  
Box Girder ◽  
Girder Bridges ◽  
System A ◽  
Thin Walled

According to the flexural and torsional characteristics of curved thin-walled box girder with the effect of initial curvature, 7 basic displacements of curved box girder are determined. And then the strain-displacement calculation correlations were established. Under the curvilinear coordinate system, a three-noded curved girder finite element which has 7 degrees of freedom per node for the vibration characteristic and dynamic response analysis of curved box girder is constructed. The shape functions are used as the interpolation functions of variable curvature and variable height to accommodate to the variation of curvature and section height. A MATLAB numerical analysis program has been implemented.

Sign in / Sign up

Export Citation Format

Share Document