Vibration of Elastic Beams in the Presence of an Inviscid Fluid Medium

2014 ◽  
Vol 14 (06) ◽  
pp. 1450022 ◽  
Author(s):  
Helnaz Soltani ◽  
Gregory S. Payette ◽  
J. N. Reddy
Keyword(s):  
Structural Response ◽  
Practical Significance ◽  
Element Formulation ◽  
Physical Interaction ◽  
Inviscid Fluid ◽  
Fluid Medium ◽  
Vast Number ◽  
Inviscid Incompressible Fluid ◽  
Vortex Induced Vibrations ◽  
Flow Through

The physical interaction of fluids and solids is of practical significance in engineering (e.g. flutter of aerodynamic structures, vortex induced vibrations of sub-sea pipelines and risers, inflatable dams, parachute dynamics and blood flow through arteries). In this paper, a finite element formulation is developed for determining the vibration characteristics of beams in contact with inviscid incompressible fluid. The classical, first-order and third-order shear deformation beam theories are used to model the structural response. Numerical results for vibration frequencies are presented showing the parametric effect of thickness and immersion depth on the frequency response. The results indicate that the presence of fluid interaction has significant effect on the dynamic response. The formulation presented herein is also applicable to a vast number of vibration problems related to beams under a variety of excitations.

Free Vibration Analysis of Elastic Plates in Contact with an Inviscid Fluid Medium

2015 ◽  
Vol 07 (03) ◽  
pp. 1550041 ◽  
Author(s):  
Helnaz Soltani ◽  
J. N. Reddy
Keyword(s):  
Finite Element ◽  
Shear Deformation ◽  
Stokes Equations ◽  
Plate Theory ◽  
Mode Shapes ◽  
Element Formulation ◽  
Inviscid Fluid ◽  
Elastic Plates ◽  
Fluid Medium ◽  
Shear Deformation Plate Theory

In the present study, a finite element formulation is presented to investigate vibration response of elastic plates in contact with a fluid medium. The fluid is assumed to be incompressible and inviscid, and the impermeability condition of the plate is taken into account. The classical plate theory (CPT), first-order shear deformation plate theory (FSDT), and Reddy third-order shear deformation plate theory (RSDT) are considered for the kinematic description of the solid medium and the simplified Navier–Stokes equations are used as the governing equations for the fluid medium. For each plate theory, a coupled set of finite element equations is derived. The effect of the fluid pressure is considered as an added mass and its effect on natural frequencies and mode shapes is investigated through several numerical simulations by varying the boundary conditions.

The Scattering of Shock Waves by Cylindrical Cavities in Liquids and Solids

1971 ◽  
Vol 38 (1) ◽  
pp. 190-196 ◽  
Author(s):  
E. Y. Harper
Keyword(s):  
Shock Wave ◽  
Asymptotic Expansion ◽  
Shielding Effect ◽  
Inviscid Fluid ◽  
Shadow Region ◽  
Shock Diffraction ◽  
Fluid Medium ◽  
Acoustic Shock Wave ◽  
Cylindrical Cavities ◽  
Logarithmic Decay

The scattering of a plane acoustic shock wave by a cylindrical cavity in an inviscid fluid medium is calculated numerically and compared with a recently obtained asymptotic expansion. In contrast to the scattering by a rigid cylinder, the cavity displays a distinctive shielding effect in the shadow region characterized by a peak exitation and an inverse logarithmic decay. Experimental results are presented which indicate a strong counterpart in plastic shock diffraction.

The Uniform Distribution of a Fluid Flowing Through a Perforated Pipe

1950 ◽  
Vol 17 (4) ◽  
pp. 431-438
Author(s):  
Willard M. Dow
Keyword(s):  
Fluid Flow ◽  
High Capacity ◽  
Practical Significance ◽  
Linear Rate ◽  
Gaseous Fuels ◽  
Extended Range ◽  
Flow Through ◽  
Perforated Pipe ◽  
Special Case ◽  
Theoretical Results

Abstract A theoretical analysis is made of the flow through a perforated pipe with a closed end for the special case of a constant linear rate of discharge along the length of the pipe. The results of the fluid-flow considerations are applicable to many practical manifold systems. The practical significance of the results with respect to pipe burners for gaseous fuels is emphasized as the results make possible the design of simple high-capacity and extended-range pipe burners of industrial importance. The capacity of commercially available pipe burners may be increased several hundred per cent. The validity of the theoretical results was verified by experiment.

Hugoniot's Method Applied to Stratified Flow through a Constriction

1972 ◽  
Vol 14 (1) ◽  
pp. 72-73 ◽  
Author(s):  
A. M. Binnie
Keyword(s):  
Stratified Flow ◽  
Horizontal Channel ◽  
Inviscid Fluid ◽  
Flow Through

The discharge of a homogeneous inviscid fluid through a convergent-divergent constriction can be calculated by Hugoniot's method. The method is here extended to stratified liquids moving under gravity in an open horizontal channel.

scholarly journals Eulerian Description of Rail Straightening Process

2014 ◽  
Vol 624 ◽  
pp. 213-217 ◽  
Author(s):  
Tomas Návrat ◽  
Jindrich Petruška
Keyword(s):  
Numerical Analysis ◽  
Material Flow ◽  
Beam Element ◽  
Fe Analysis ◽  
Lagrangian Description ◽  
Element Formulation ◽  
Deformation Effect ◽  
Plastic Bending ◽  
Eulerian Description ◽  
Flow Through

The paper deals with numerical analysis of the process of roller straightening of rails. The problem of repeated elasto-plastic bending is solved by a program in MATLAB based on FEM algorithm with Eulerian description of material flow through the straightening machine. Beam element formulation with a shear deformation effect is used for the rail discretization. The results are compared with literature and standard FE analysis with Lagrangian description of material flow. Effectiveness of presented formulation is discussed and its applicability for fast iterative optimization of the straightening process is illustrated.

POD Analysis of the Wake Development of a Pivoted Circular Cylinder Undergoing Vortex Induced Vibrations

2017 ◽  
Author(s):  
E. Marble ◽  
C. Morton ◽  
S. Yarusevych
Keyword(s):  
Circular Cylinder ◽  
Degrees Of Freedom ◽  
Structural Response ◽  
Cylinder Wake ◽  
Time Resolved ◽  
Vortex Induced Vibrations ◽  
Image Velocimetry ◽  
Pod Analysis ◽  
Component Particle ◽  
Proper Orthogonal

Vortex Induced Vibrations (VIV) of a pivoted circular cylinder with two degrees of freedom are investigated experimentally, focusing on quantifying the wake topology. Experiments are performed in a water tunnel for a pivoted cylinder with a fixed mass ratio of 10.8, moment of inertia ratio of 87.0–109.5, and a diameter-based Reynolds number of 3100. The reduced velocity was varied from 4.42 to 9.05 by varying the natural frequency of the structure. Velocity measurements were performed via time-resolved, two-component Particle Image Velocimetry (PIV), synchronized with cylinder displacement measurements. Time and phase-averaging are employed to analyze the wake development and relate it to the structural response. Proper Orthogonal Decomposition (POD) is utilized to gain insight into the development of coherent structures in the cylinder wake. The observed shedding patterns agree well with the Morse & Williamson [1] shedding map except for the cases at the boundary between 2P and non-synchronized shedding. The results show that the cylinder follows an elliptical trajectory with equal frequency of oscillation in streamwise and transverse directions. For the 2P regime, the tilt and direction of trajectory affect the formation and development of vortices in the wake. This results in a distinct asymmetry about the wake centerline in time-averaged statistics.

Structural Response of Pipeline Free Spans Based on Beam Theory

2002 ◽  
Author(s):  
Olav Fyrileiv ◽  
Kim Mo̸rk
Keyword(s):  
Natural Frequencies ◽  
Structural Response ◽  
Beam Theory ◽  
Vertical Vibration ◽  
Mode Shapes ◽  
Ocean Current ◽  
Vibration Modes ◽  
Wave Loading ◽  
Vortex Induced Vibrations ◽  
Subsea Pipelines

One of the main risk factors for subsea pipelines exposed on the seabed is fatigue failure of free spans due to ocean current or wave loading. This paper describes how the structural response of a free span, as input to the fatigue analyses, can be assessed in a simple and still accurate way by using improved beam theory formulations. In connection with the release of the DNV Recommended Practice, DNV-RP-F105 “Free Spanning Pipelines”, the simplified structural response quantities have been improved compared to previous codes. The boundary condition coefficients for the beam theory formulations have been updated based an effective span length concept. This concept is partly based on theoretical studies and partly on a large number of FE analyses. The updated expressions are general and fit all types of soil and pipe dimensions for lower lateral and vertical vibration modes. The present paper focus on estimation of simplified response quantities such as lower natural frequencies and associated mode shapes. Hydrodynamical aspects of Vortex Induced Vibrations (VIV) are outside the scope of this paper.

Finite Element Analysis of the Thermal and Mechanical Behaviors of Bolted Joint

2003 ◽  
Author(s):  
Toshimichi Fukuoka
Keyword(s):  
Finite Element ◽  
Heat Flow ◽  
Gas Turbines ◽  
Internal Combustion Engines ◽  
Thermal Contact ◽  
Numerical Procedure ◽  
Pressure Vessels ◽  
Element Formulation ◽  
Bolted Joint ◽  
Flow Through

Mechanical and thermal behaviors of the bolted joint subjected to thermal load are analyzed using axisymmetric FEM, where the effects of thermal contact resistance at the interface and heat flow through small gaps are taken into account in order to accurately evaluate the variations of bolt preloads. It is expected that the numerical procedure proposed here provides an effective means for estimating the strength of such critical structures as internal combustion engines, pressure vessels, steam and gas turbines, etc. An empirical equation that can compute the thermal contact coefficient at the interface composed of common engineering materials has been proposed in the previous paper. In this study, a simple equation for evaluating the amounts of heat flow through small gaps is shown by defining apparent thermal contact coefficient. A finite element approach has been established by incorporating the aforementioned thermal contact coefficients into the finite element formulation. By use of the FE code, it is shown that among various thermal properties, coefficient of linear expansion has dominant effects on the variations of bolt preloads. The validity of the numerical approach is demonstrated by experimentation.

Two-Dimensional Geometrically Nonlinear Finite Element Formulation for Analysis of Straight Pipes

2020 ◽  
Author(s):  
Saher Attia ◽  
Magdi Mohareb ◽  
Michael Martens ◽  
Nader Yoosef Ghodsi ◽  
Yong Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Virtual Work ◽  
Strain Tensor ◽  
Structural Response ◽  
Small Strain ◽  
Nonlinear Finite Element ◽  
Finite Element Formulation ◽  
Single Element ◽  
Element Formulation ◽  
Geometrically Nonlinear

Abstract The paper presents a new and simple geometrically nonlinear finite element formulation to simulate the structural response of straight pipes under in-plane loading and/or internal pressure. The formulation employs the Green-Lagrange strain tensor to capture finite deformation-small strain effects. Additionally, the First Piola-Kirchhoff stress tensor and Saint Venant-Kirchhoff constitutive model are adopted within the principle of virtual work framework in conjunction with a total Lagrangian approach. The formulation is applied for a cantilever beam under three loading conditions. Results are in good agreement with shell models in ABAQUS. Although the solution is based on a single element, the formulation provides reasonable displacement and stress predictions.

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