Dynamic Behavior of String Subjected to Travelling Mass

2019 ◽  
Author(s):  
Shakti P. Jena ◽  
S. Naresh Kumar ◽  
Hemanth Cheedella
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Green’S Function ◽  
Dynamic Behavior ◽  
Green's Function ◽  
Transverse Vibration ◽  
Element Model ◽  
Numerical Approach ◽  
Complete Analysis ◽  
Numerical Example

Abstract The present study is based on the transverse vibration analogy of a string subjected to a travelling mass. The string is considered to be fixed at their both ends. The responses of the string due to the dynamic behavior of the travelling mass are determined using a numerical approach i.e. Green’s function. A Finite Element Model (FEM) has been developed to authenticate the numerical approach. For the responses analysis of the string, numerical example has been illustrated to study the behavior of the string due to the travelling mass and to check the convergence of the two proposed analogies (Green’s function and FEM). The complete analysis has been performed at constant travelling speed and different masses. The two approaches converge well and the Green’s function methodology found to be suitable one.

Anisotropic Heat Analysis Using Hybrid Finite Element Model with Element Boundary Integrals

2011 ◽  
Vol 199-200 ◽  
pp. 1613-1616
Author(s):  
Hui Wang ◽  
Xin Juan Zhao
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Finite Element Model ◽  
Green’S Function ◽  
Green's Function ◽  
Element Model ◽  
Internal Field ◽  
Anisotropic Materials ◽  
Boundary Integrals ◽  
Hybrid Finite Element

Anisotropic materials have been widely applied in practical engineering problems of interest. In the paper, the anisotropic heat transfer behaviors are analyzed using the proposed hybrid finite element model with Green’s function kernel. In the established weak integral hybrid functional, the element internal field being approximated with the combination of Green’s function satisfies a priori the governing partial differential equation and the independent frame field is assumed to link the internal field. As a result, the solving linear system of equations with boundary integrals only is obtained and the constructed elements show anisotropic feature. Two numerical examples are given to show the convergence and accuracy of the proposed approach, and the effect of ply angle of orthotropic material principal direction on the temperature distribution is discussed to investigate heat transfer mechanism in anisotropic materials.

scholarly journals Modeling of Self-Vibratory Drilling Head-Spindle System for Predictions of Bearings Lifespan

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
F. Forestier ◽  
V. Gagnol ◽  
P. Ray ◽  
H. Paris
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Behavior ◽  
Potential Risk ◽  
Feed Rate ◽  
High Speed ◽  
Element Model ◽  
Experimental Measurements ◽  
Alternative Response ◽  
Tool Breakage

The machining of deep holes is limited due to inadequate chip evacuation, which induces tool breakage. To limit this drawback, retreat cycles and lubrication are used. An alternative response to the evacuation problem is based on high-speed vibratory drilling. A specific tool holder induces axial self-maintained vibration of the drill, which enables the chips to be split. The chips are thus of a small size and can be evacuated. To anticipate the potential risk of decreased spindle lifespan associated with these vibrations, a model of the behavior of the system (spindle—self-vibrating drilling head—tool) is elaborated. In order to assess the dynamic behavior of the system, this study develops a rotor-based finite element model, integrated with the modelling of component interfaces. The current results indicate that the simulations are consistent with the experimental measurements. The influence of spindle speed and feed rate on bearing lifespan is highlighted.

Numerical approach for axisymmetric piezoceramic geometries towards fluid control applications

2000 ◽  
Vol 214 (2) ◽  
pp. 87-97 ◽  
Author(s):  
S M Peelamedu ◽  
C B Kosaraju ◽  
R V Dukkipati ◽  
N G Naganathan
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Single Layer ◽  
Element Model ◽  
Numerical Approach ◽  
Numerical Results ◽  
Control Applications ◽  
Fluid Control ◽  
Inkjet Printer ◽  
Finite Element Methodology

Piezoceramics have been increasingly popular and utilized for the purpose of micro-actuation. The choice of material internal poling directions for such geometries depends upon the type of actuation desired in each application. There are no generalized analysis procedures that have been developed to be able to predict the response of such actuator geometries. In this work, a finite element model has been developed to analyse axisymmetric piezoceramic actuators with arbitrary internal poling. The finite element methodology is verified by demonstrating favourable agreement between the numerical results obtained in this study with the results published for an inkjet printer application. In addition, the design of a piezoceramic nozzle is investigated with both single-layer and stacked axisymmetric piezoceramic geometries. Such piezoceramic nozzles and orifices can be effectively employed in various sensitive fluid control applications.

scholarly journals Numerical Simulations of Dynamic Behavior of Polyurea Toughened Steel Plates under Impact Loading

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Chien-Chung Chen ◽  
Daniel G. Linzell
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Behavior ◽  
Impact Loading ◽  
Numerical Models ◽  
Model Development ◽  
Time History ◽  
Element Model ◽  
Steel Plates ◽  
Numerical Work

The objective of the work discussed herein is to develop a nonlinear 3D finite element model to simulate dynamic behavior of polyurea toughened steel plates under impact loading. Experimental and numerical work related to model development are presented. Material properties are incorporated into numerical models to account for strain-rate effects on the dynamic behavior of polyurea and steel. One bare steel plate and four polyurea toughened steel plates were tested under impact loading using a pendulum impact device. Displacement time-history data from experimental work was used to validate the numerical models. Details on material model construction, finite element model development, and model validation are presented and discussed. Results indicate that the developed numerical models can reasonably predict dynamic response of polyurea toughened steel plates under impact loading.

An Efficient Approach for the Frequency Analysis of Nonaxisymmetric Rotating Structures: Application to a Coupled Bladed Birotor System

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Cécile Dumartineix ◽  
Benjamin Chouvion ◽  
Fabrice Thouverez ◽  
Marie-Océane Parent
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Behavior ◽  
Frequency Analysis ◽  
Equations Of Motion ◽  
Element Model ◽  
Variable Coefficients ◽  
Time Dependent ◽  
Time Saving ◽  
Mechanical Coupling

The improvement of efficiency in the design of turbomachines requires a reliable prediction of the vibrating behavior of the whole structure. The simulation of blades vibrations is decisive and this is usually based on elaborated finite element model restricted to the bladed-disk. However, the blades dynamic behavior can be strongly affected by interactions with other parts of the engine. Global dynamic studies that consider these other parts are required but usually come with a high numerical cost. In the case of a birotor architecture, two coaxial rotors with different rotating speeds can be coupled with a bearing system. The mechanical coupling between the shafts generates energy exchange that alters the dynamic behavior of the blades. The equations of motion of the whole structure that take into account the coupling contain periodic time-dependent coefficients due to the difference of rotational speed between both rotors. Equations of this kind, with variable coefficients, are typically difficult to solve. This study presents a preprocessing method to guarantee the elimination of time-dependent coefficients in the birotor equations of motion. This method is tested with a simplified finite element model of two bladed-disks coupled with linear stiffnesses. We obtain accurate results when comparing frequency analysis of preprocessed equations with time-integration resolution of the initial set of equations. The developed methodology also offers a substantial time saving.

Towards Dynamic Tolerance Analysis Using a Finite Element Formulation

2000 ◽  
Author(s):  
Otto Salomons ◽  
Elmer Arentsen ◽  
Ronald Aarts ◽  
Fred van Houten
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Behavior ◽  
Geometric Model ◽  
Tolerance Analysis ◽  
Element Model ◽  
Finite Element Formulation ◽  
Element Formulation ◽  
Large Numbers ◽  
Physical Effects

Abstract A theoretical framework is proposed by which the effect of tolerances can be analyzed. Especially it focuses on the influence of clearances on the dynamic behavior of mechanisms. As opposed to previous publications, where a bondgraph formulation was used, this paper uses a finite element formulation in order to simulate the dynamic behavior under the influence of tolerances and other physical effects. The finite element formulation that has been selected for this work has two major advantages when compared to a bondgraph formulation. The first important advantage is that the method is analytical to a great extent. As a result, no numerically derived derivatives will exist, hence not leading to numeric inaccuracies. The second advantage is that small numbers can be separated from large numbers allowing to separate tolerances from the nominal path, resulting in faster simulations. The paper describes how a geometric model, including its tolerances, can be transformed into a corresponding finite element model that on its part consists of submodels. Based on this model, simulations can be performed which can provide insight in the dynamic behavior of the mechanism. The paper details on how geometric tolerances (such as form, orientation, position as well as size and clearances), with the focus on clearances, can be accounted for in a finite element model.

Damping Control in a Sandwich Structure With SMP Core

2015 ◽  
Author(s):  
Pauline Butaud ◽  
Morvan Ouisse ◽  
Emmanuel Foltête
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Sandwich Structure ◽  
Damping Ratio ◽  
Shape Memory Polymer ◽  
Viscoelastic Model ◽  
Element Model ◽  
Numerical Approach ◽  
Wide Frequency Range ◽  
Frequency Range

A shape memory polymer (SMP), the tBA/PEGDMA, is elaborated and characterized. The dynamic mechanical characterization of this SMP highlights promising damping properties. The frequency and temperature dependency of the SMP is represented by a viscoelastic model allowing the introduction of the material in the design process of complex structures. A composite sandwich is developed by coupling the SMP with aluminum skins. A finite element model is developed for modeling the behavior of the SMP when integrated in a sandwich structure. The damping performances obtained by the numerical approach are validated experimentally using modal analysis. The experimental results are found to be in good agreement with the predictions of the finite element model. Furthermore, it is found that the controlled heating of the SMP core allows damping the structure over a wide frequency range. The SMP core temperature is tuned from the time-temperature superposition through a calibration curve to correspond to optimal values of damping ratio in the frequency range of interest; a vibration attenuation of about 20dB is observed.

scholarly journals A Fully Parameterized Finite Element Model of a Grand Piano Soundboard for Sensitivity Analysis of the Dynamic Behavior

2013 ◽  
Author(s):  
Fatma Mokdad ◽  
Samy Missoum
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Behavior ◽  
Rank Correlation ◽  
Element Model ◽  
Spearman Rank Correlation ◽  
Material Parameters ◽  
Modal Behavior ◽  
Grand Piano

This work in progress aims at investigating the influence of several parameters on the modal behavior of a grand piano soundboard. The sensitivity analysis is made possible by the development of a fully parameterized Finite Element model of the soundboard which allows the user to modify most geometric and material parameters involved in its dynamic behavior. In addition, crowning and downbearing are included in the model. This study also considers the influence of geometric nonlinearities due to downbearing. The sensitivity analysis is performed using Spearman rank correlation and Sobol indices.

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