Numerical Wave Tanks Based on Finite Element and Boundary Element Modeling

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
R. Eatock Taylor ◽  
G. X. Wu ◽  
W. Bai ◽  
Z. Z. Hu
Keyword(s):  
Finite Element ◽  
Boundary Element ◽  
Adaptive Mesh ◽  
Element Model ◽  
The Body ◽  
Test Cases ◽  
Fe Model ◽  
Transient Waves ◽  
Adaptive Mesh Generation ◽  
Nonlinear Diffraction

This work forms part of an investigation into the nonlinear interaction between steep (but not overturning) transient waves and flared structures, using a coupled finite element and boundary element model. The use of a coupled approach is based on consideration of the relative strengths and weaknesses of the finite element (FE) and boundary element (BE) methods when implemented separately (e.g., efficiency of computation versus complexity of adaptive mesh generation). A FE model can be used to advantage away from the body, where the domain is regular, and a BE discretization near the body where the moving mesh is complex. This paper describes the aspects of the FE and BE models which have been developed for this analysis, each based on the use of quadratic isoparametric elements implemented in a mixed Eulerian–Lagrangian formulation. Initially, the two approaches have been developed side by side, in order to ensure the use of robust components in the coupled formulation. Results from these methods are obtained for a series of test cases, including the interaction of an impulse wave with a circular cylinder in a circular tank, and nonlinear diffraction by a cylinder in a long tank.

Numerical Wave Tanks Based on Finite Element and Boundary Element Modelling

2005 ◽  
Author(s):  
R. Eatock Taylor ◽  
G. X. Wu ◽  
W. Bai ◽  
Z. Z. Hu
Keyword(s):  
Finite Element ◽  
Boundary Element ◽  
Adaptive Mesh ◽  
Element Model ◽  
The Body ◽  
Test Cases ◽  
Fe Model ◽  
Linear Interaction ◽  
Adaptive Mesh Generation ◽  
Non Linear

This work forms part of an investigation into the non-linear interaction between steep transient waves and flared structures, using a coupled finite element and boundary element model. The use of a coupled approach is based on consideration of the relative strengths and weaknesses of the finite element (FE) and boundary element (BE) methods when implemented separately (e.g. efficiency of computation versus complexity of adaptive mesh generation). An FE model can be used to advantage away from the body, where the domain is regular, and a BE discretisation near the body where the moving mesh is complex. The paper describes aspects of the FE and BE models which have been developed for this analysis, each based on the use of quadratic isoparametric elements implemented in a mixed Eulerian-Lagrangian formulation. Initially the two approaches have been developed side by side, in order to ensure the use of robust components in the coupled formulation. Results from these methods are obtained for a series of test cases, including the interaction of an impulse wave with a circular cylinder in a circular tank, and non-linear diffraction by a cylinder in a long tank.

Multi-Purpose Flexible Bodies Integration Into the Multi-Body System of a Metro-Vehicle

2010 ◽  
Author(s):  
Guido Saporito ◽  
Alessandro Baroni ◽  
Mario Romani
Keyword(s):  
Finite Element ◽  
Element Model ◽  
The Body ◽  
Fe Model ◽  
Body System ◽  
Bogie Frame ◽  
Flexible Bodies ◽  
Multi Body ◽  
The Finite Element Model ◽  
Analytical Verification

The work points to study the effects of bodies flexibility concerning the Running Dynamics and Structural requirements and how such aspects could be integrated into a single design process of a mass transit vehicle in terms of Comfort, Safety, Track fatigue and Bogie-frame design. The multi-body system of the vehicle has been developed. The finite element model of the flexible bodies as car-body, wheel-set, bolster-beam and bogie-frame have been implemented. The critical but necessary step, in the integration process of the flexible body into a multi-body system, is the reduction of the finite element model of the body. For that reason an analytical verification in focused to validate the reduced FE-model with respect to the full FE-model has been thought, developed and implemented to provide a useful design tool; such an analytical verification aids the engineer to control and to optimize the reduction technique applied to the full-FE-model of the body. The validation procedure, which has been implemented, consists in developing an alter for the DMAP, Direct Matrix Abstraction Program of the FE-solver, and processing the output into a programming environment.

The Study of Stress Distribution on Meniscus Using 3D Finite Element Model

2015 ◽  
Vol 749 ◽  
pp. 427-432
Author(s):  
Pavinee Laopachee ◽  
Pattaraweerin Woraratsoontorn ◽  
Joompondej Bamrungwongtaree
Keyword(s):  
Finite Element ◽  
Body Weight ◽  
Stress Distribution ◽  
Knee Joint ◽  
External Load ◽  
Element Model ◽  
The Body ◽  
Three Dimensions ◽  
Von Mises Stress ◽  
Fe Model

Osteoarthritis is a degenerative disease of articular cartilageand meniscus that most experience in aged and obesity, always tend to grow up. Such bone surface degenerated will beirregular and has bone to grow called osteophyte. At moment making activities, the pain and the deformation of the knee joint are occurred thatcause decreasing quality of life. The deterioratedmeniscus has to encountersgradually changing the structureuntil it is not able to support the body weight. This paper proposes the preliminary studyof the knee jointbehavior, especially the meniscus during stand. Three dimensions (3-D) finite element (FE) model of the knee joint has constructed. This model consisted of femur, tibiaand meniscus without fibula.The external load were determined in each body weight and appliedon femur to evaluate maximum von-mises stress on the meniscus.The stress distribution on meniscus always occurs while exist the external load on the femur. The tendency of association between the external load and maximumstress was corresponding to that of the other author.

An Assessed Model for the Vibro-Acoustic Analysis of Gear Pumps

2013 ◽  
Author(s):  
Emiliano Mucchi ◽  
Giorgio Dalpiaz
Keyword(s):  
Finite Element ◽  
Boundary Element ◽  
Acoustic Analysis ◽  
Simulated Data ◽  
Element Model ◽  
Lumped Parameter Model ◽  
Fe Model ◽  
Gear Pump ◽  
Operational Conditions ◽  
Lumped Parameter

In this work a combined model for the vibro-acoustic analysis of an external gear pump for automotive applications is presented and experimentally assessed. The model includes a lumped-parameter model, a finite-element model and a boundary-element model. The lumped-parameter (LP) model regards the interior parts of the pump (bearing blocks and gears), the finite element (FE) model regards the external parts of the pump (casing and end plates), while the boundary element (BE) model estimates the noise generation in operational conditions. Attention has been devoted to the inclusion of the oil effect inside the pump casing: the fluid-structure interaction between oil and pump casing was taken into account. The model has been assessed using experiments: the experimental accelerations and acoustic pressure measured in operational conditions have been compared with the simulated data coming from the combined LP/FE/BE model. Eventually, model results and limitations are presented.

COUPLED BOUNDARY ELEMENT-FINITE ELEMENT MODEL TO ESTIMATE HUMAN HEEL-PAD ELASTICITY MODULUS

2017 ◽  
Vol 29 (03) ◽  
pp. 1750018
Author(s):  
Amirhossein Salimi ◽  
Hamid-Reza Katouzian ◽  
Paniz Naraghi-Bagherpour ◽  
Mohammad-Mehdi Khani
Keyword(s):  
Finite Element ◽  
Boundary Element ◽  
Computational Cost ◽  
Element Model ◽  
Elastic Behavior ◽  
Fe Model ◽  
Heel Pad ◽  
Local Stresses ◽  
Indentation Experiment

The key role of heel-pad in protecting calcaneus bone against excessive local stresses during walking and running is well discussed in the literature. Aiming to obtain a more profound understanding of this soft collagenous load-bearing tissue, material characterization of heel-pad has attracted the attention of many researchers. One way of achieving this goal is to estimate the mechanical properties of heel-pad based on Finite Element (FE) simulation of the indentation experiment which has been conducted by various teams before. During this process, the soft tissue undergoes a relatively large deformation causing the elements in FE Model to be extremely distorted particularly near the vicinity of indenter-heel pad contact making the numerical modeling tedious and significantly increasing the computational cost. The main contribution of the current study is to develop a coupled Boundary Element–Finite Element (BE–FE) plane strain model to improve the deficiency of the conventional numerical methods as the three-node 1 degree-of-freedom BEs eliminate the distortion issue near the deformed heel-pad zone and effectively lower the computational costs which is vital for iterative processes of this kind. Later through iterative post-processing of data, the modulus of elasticity (E) describing the elastic behavior of heel-pad is extracted. E is determined by using the inverse technique to minimize the displacement error between the experimental data and the corresponding numerical results after a considerable number of iterations. Obtained results contribute in design and construction of state-of-the-art prosthetic feet and therapeutic foot wear.

Finite Element Analysis of the Distributed Vibration Absorbers for Structural Noise Control

2005 ◽  
Author(s):  
Ashwini Gautam ◽  
Chris Fuller ◽  
James Carneal
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Base Plate ◽  
Element Model ◽  
Fe Model ◽  
Vibration Absorbers ◽  
Element Analysis ◽  
Poroelastic Media ◽  
Hexahedral Elements ◽  
Component Models

This work presents an extensive analysis of the properties of distributed vibration absorbers (DVAs) and their effectiveness in controlling the sound radiation from the base structure. The DVA acts as a distributed mass absorber consisting of a thin metal sheet covering a layer of acoustic foam (porous media) that behaves like a distributed spring-mass-damper system. To assess the effectiveness of these DVAs in controlling the vibration of the base structures (plate) a detailed finite elements model has been developed for the DVA and base plate structure. The foam was modeled as a poroelastic media using 8 node hexahedral elements. The structural (plate) domain was modeled using 16 degree of freedom plate elements. Each of the finite element models have been validated by comparing the numerical results with the available analytical and experimental results. These component models were combined to model the DVA. Preliminary experiments conducted on the DVAs have shown an excellent agreement between the results obtained from the numerical model of the DVA and from the experiments. The component models and the DVA model were then combined into a larger FE model comprised of a base plate with the DVA treatment on its surface. The results from the simulation of this numerical model have shown that there has been a significant reduction in the vibration levels of the base plate due to DVA treatment on it. It has been shown from this work that the inclusion of the DVAs on the base plate reduces their vibration response and therefore the radiated noise. Moreover, the detailed development of the finite element model for the foam has provided us with the capability to analyze the physics behind the behavior of the distributed vibration absorbers (DVAs) and to develop more optimized designs for the same.

Finite Element Model of Human Cochlea Considering of the Helicotrema Size

2013 ◽  
Vol 456 ◽  
pp. 576-581 ◽  
Author(s):  
Li Fu Xu ◽  
Na Ta ◽  
Zhu Shi Rao ◽  
Jia Bin Tian
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Basilar Membrane ◽  
Round Window ◽  
Element Model ◽  
Oval Window ◽  
Fe Model ◽  
Cochlear Duct ◽  
Human Cochlea ◽  
Set Up

A 2-D finite element model of human cochlea is established in this paper. This model includes the structure of oval window, round window, basilar membrane and cochlear duct which is filled with fluid. The basilar membrane responses are calculated with sound input on the oval window membrane. In order to study the effects of helicotrema on basilar membrane response, three different helicotrema dimensions are set up in the FE model. A two-way fluid-structure interaction numerical method is used to compute the responses in the cochlea. The influence of the helicotrema is acquired and the frequency selectivity of the basilar membrane motion along the cochlear duct is predicted. These results agree with the experiments and indicate much better results are obtained with appropriate helicotrema size.

Numerical Prediction of Noise Radiated From a Panel Subjected to Boundary Layer Excitation

1999 ◽  
Author(s):  
Michael Allen ◽  
Nickolas Vlahopoulos
Keyword(s):  
Boundary Layer ◽  
Finite Element ◽  
Boundary Element ◽  
Transfer Functions ◽  
Element Model ◽  
Acoustic Response ◽  
Spectral Densities ◽  
Wind Noise ◽  
Element Analysis ◽  
Power Spectral

Abstract In this paper an algorithm is developed for combining finite element analysis and boundary element techniques in order to compute the noise radiated from a panel subjected to boundary layer excitation. The excitation is presented in terms of the auto and cross power spectral densities of the fluctuating wall pressure. The structural finite element model for the panel is divided into a number of sub-panels. A uniform fluctuating pressure is applied as excitation on each sub-panel separately. The corresponding vibration is computed, and is utilized as excitation for an acoustic boundary element analysis. The acoustic response is computed at any data recovery point of interest. The relationships between the acoustic response and the pressure excitation applied at each particular sub-panel constitute a set of transfer functions. They are combined with the spectral densities of the excitation for computing the noise generated from the vibration of the panel subjected to the boundary layer excitation. The development presented in this paper has the potential of computing wind noise in automotive applications, or boundary layer noise in aircraft applications.

Finite Element Mesh Generator Applying Constraints’ Propagation and Isoparametric Mapping

1991 ◽  
Author(s):  
J. Rodriguez ◽  
M. Him
Keyword(s):  
Finite Element ◽  
Mesh Generation ◽  
Element Model ◽  
Finite Element Mesh ◽  
Fe Model ◽  
Element Analysis ◽  
Element Mesh ◽  
Mesh Generator ◽  
Generation Algorithm ◽  
Essential Input

Abstract This paper presents a finite element mesh generation algorithm (PREPAT) designed to automatically discretize two-dimensional domains. The mesh generation algorithm is a mapping scheme which creates a uniform isoparametric FE model based on a pre-partitioned domain of the component. The proposed algorithm provides a faster and more accurate tool in the pre-processing phase of a Finite Element Analysis (FEA). A primary goal of the developed mesh generator is to create a finite element model requiring only essential input from the analyst. As a result, the generator code utilizes only a sketch, based on geometric primitives, and information relating to loading/boundary conditions. These conditions represents the constraints that are propagated throughout the model and the available finite elements are uniformly mapped in the resulting sub-domains. Relative advantages and limitations of the mesh generator are discussed. Examples are presented to illustrate the accuracy, efficiency and applicability of PREPAT.

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