Simulation of Static Performance of Air Foil Bearings Using Coupled Finite Element and Computational Fluid Dynamics Techniques

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Leonidas I. Paouris ◽  
Dimitrios A. Bompos ◽  
Pantelis G. Nikolakopoulos
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Pressure Distribution ◽  
Carrying Capacity ◽  
Stokes Equations ◽  
Element Model ◽  
Elastic Behavior ◽  
Navier Stokes ◽  
Load Carrying Capacity ◽  
Load Carrying

The main objective of the current work is to determine a relationship between the top and bump foil's geometry and load-carrying capacity in a journal compliant generation I air foil bearing, as well as determining the effect of the thermohydrodynamic phenomena in the performance of the air foil bearing (AFB). Static and steady-state operation is assumed throughout the analysis. A finite element model is adopted in order to investigate the operational characteristics of the specific bearing. Bump foil's elastic behavior is modeled using two node linear link spring elements. During the hydrodynamic analysis, incompressible viscous steady state Navier–Stokes equations are numerically solved, due to the low bearing compressibility number. During the thermohydrodynamic analysis, compressible, viscous, steady-state Navier–Stokes equations were solved, coupled with the energy equation. The material used during the structural analysis is Inconel X750, and it is assumed that it has linear and elastic behavior. Constant ambient pressure is applied at the free faces of the fluid as well as no slip condition at the surface of the fluid that faces the top foil. Computational fluid dynamics (CFD) and structural models are solved separately. At the beginning of the analysis, the CFD problem is solved with the assumption that the top foil has not yet been deformed. After the solution of the CFD problem, the pressure distribution at the surface of the fluid that faces the top foil is applied at the top foil and then the structural problem is solved. Consequently, the deflections of the top foil are applied on the corresponding surface of the CFD model and the algorithm continues until convergence is obtained. As soon as the converged solution for the pressure distribution is obtained, numerical integration is performed along the surface of the bearing in order to calculate its load-carrying capacity. Static bearing performance characteristics, such as pressure distribution, bump foil deflection, and load capacity are calculated and presented. Furthermore, fluid film thickness, top foil deflection, and fluid pressure are investigated as functions of the bearing angle as well as load-carrying capacity as a function of the bump and top foil stiffness. The same procedure is repeated for the thermohydrodynamic analysis. Moreover, in order to estimate the heat flux from the top foil to the bump foil channel as a function of the top foil temperature, a simple finite element model of the bump foil–cooling channel is constructed.

Simulation of Static Performance of Air Foil Bearings Using Coupled FEM and CFD Techniques

2013 ◽  
Author(s):  
Leonidas I. Paouris ◽  
Dimitrios A. Bompos ◽  
Pantelis G. Nikolakopoulos
Keyword(s):  
Steady State ◽  
Pressure Distribution ◽  
Carrying Capacity ◽  
Stokes Equations ◽  
Ambient Pressure ◽  
Elastic Behavior ◽  
Foil Thickness ◽  
Load Carrying Capacity ◽  
Structural Problem ◽  
Load Carrying

The main objective of the current work is to determine a relationship between the top and bump foil’s geometry and load carrying capacity in a journal compliant air foil bearing. Static and steady state operation is assumed throughout the analysis. A finite element model is adopted in order to investigate the operational characteristics of the specific bearing. Bump foil’s elastic behavior is modeled using two node linear spring elements. During fluid analysis, compressible viscous steady state Navier-Stokes equations are numerically solved. The material used during the structural analysis is Inconel X750 and it is assumed that it has linear and elastic behavior. Thermal effects are not taken under consideration. Constant ambient pressure is applied at the free faces of the fluid as well as no slip condition at the surface of the fluid that faces the top foil. CFD and structural models are solved separately. At the beginning of the analysis CFD problem is solved with the assumption that the top foil has not yet been deformed. After the solution of the CFD problem, the pressure distribution at the surface of the fluid that faces the top foil is applied at the top foil and then the structural problem is solved. Consequently the deflections of the top foil are applied on the corresponding surface of the CFD model and the algorithm continues until convergence is obtained. As soon as the converged solution for the pressure distribution is obtained, numerical integration is performed along the surface of the bearing in order to calculate its load carrying capacity. The same procedure is repeated for different values of bump foil thickness, height and pitch in order to define a pattern that describes the bearing’s load carrying capacity as a function of the geometric parameters of the structural problem. Static bearing performance characteristics, such as pressure distribution, bump foil deflection and load capacity are calculated and presented. Furthermore fluid film thickness, top foil deflection and fluid pressure are investigated as functions of the bearing angle as well as load carrying capacity as a function of the bump and top foil stiffness. Finally, a simple thermal analysis is incorporated in order to estimate the temperature rise in the CFD domain due to viscous heat.

Determination of the Load Carrying Capacity of Honeycomb Panels at Fixing Points under an External Load

2020 ◽  
Vol 299 ◽  
pp. 1184-1189
Author(s):  
V.V. Zhukov ◽  
Anton V. Eremin ◽  
D.V. Stepanec
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Finite Element Model ◽  
Carrying Capacity ◽  
External Load ◽  
Element Model ◽  
Load Carrying Capacity ◽  
The Finite Element Method ◽  
Load Carrying ◽  
Honeycomb Panel

In this article, the object of study is a three–layer honeycomb panel with fixing elements (FE), which are used for transporting the panel, and fixing it to the spacecraft. The goal of the work is to determine experimentally the load carrying capacity of the fixing elements under various types of loading, to determine the load carrying capacity of the honeycomb panel of the spacecraft at fixing points and further comparison of the experimental results with the finite element method results calculated by MSC.Patran / Nastran. A method for conducting static tests of fixing elements of a spacecraft honeycomb panel under an external load is described, a description of computer technology of a finite–element solution to the problem of static strength of a honeycomb panel structure in the MSC.Patran environment is presented, and a finite–element model of a honeycomb panel is designed. An assessment of the strength of a three–layer structure at fixing points was carried out, followed by validation of the finite–element model of a honeycomb panel. On the basis of the validated model, the evaluation of the strength of the honeycomb structure was carried out; based on results obtained, the conclusion has been made about the convergence of the results by the finite element method with the results obtained during the experiment.

Analysis of the Load-Carrying Capability of the Casing Plug Joint of Steel Tube Structures Considering the Contact Effect

2008 ◽  
Vol 33-37 ◽  
pp. 321-326 ◽  
Author(s):  
Xiu Gen Jiang ◽  
Yang Yang ◽  
Feng Jie Zhang ◽  
Jin San Ju ◽  
Xiao Chuan You
Keyword(s):  
Finite Element ◽  
Carrying Capacity ◽  
Element Model ◽  
Steel Tube ◽  
Nonlinear Finite Element ◽  
Tube Length ◽  
Load Carrying Capacity ◽  
Ansys Software ◽  
Load Carrying ◽  
Nonlinear Finite Element Model

Nonlinear finite element model analysis of the casing plug joints of steel tubular has been realized by ANSYS software. The law of load-carrying capability and stiffness of joint are separately gained by changing the ratio of length and diameter (R/L) and the ratio of the casing length and the main tube length (l/L). The influence of the casing thickness on the load-carrying capability and stiffness are also discussed. The results indicated that the load-carrying capability and stiffness of the joints both increase with the ratio(R/L) increment and the ratio of the casing length and main tube length (l/L). When the main tube thickness is equal to casing thickness, the load-carrying capacity of joints achieves the most.

scholarly journals Axial Load-carrying Capacity of Steel Tubed Concrete Short Columns Confined with Advanced FRP Composites

2020 ◽  
Author(s):  
Ali Raza ◽  
Syyed Adnan Raheel Shah ◽  
Mudasser Muneer Khan ◽  
Faraz ul Haq ◽  
Hunain Arshad ◽  
...  
Keyword(s):  
Finite Element ◽  
Compressive Strength ◽  
Finite Element Model ◽  
Carrying Capacity ◽  
Axial Load ◽  
Element Model ◽  
Confined Concrete ◽  
Superior Performance ◽  
Load Carrying Capacity ◽  
Load Carrying

Fiber Reinforced Polymers (FRPs) have wide applications in the field of concrete construction due to their superior performance over conventional materials. This research focuses on the structural behavior of steel tube FRP jacket–confined concrete (STFC) columns under axial concentric loading and proposes a new empirical equation for predicting the axial load-carrying capacity of STFC columns having thickness of FRP-fabric ranging from 0.09 mm to 5.9 mm. A large database of 700 FRP-confined concrete specimens is developed with the detailed information of critical parameters, i.e. elastic modulus of FRPs (Ef), compressive strength of unconfined concrete (fc’o), diameter of specimen (D), height of specimen (H), total thickness of FRPs (N.tf), and the ultimate strength of confined concrete (fc’c). After the preliminary evaluation of constructed database, a new empirical model is proposed for the prediction of axial compressive strength of FRP-confined specimens using general regression analysis by minimizing the error functions such as root mean squared error (RMSE) and coefficient of determination (R2). The proposed FRP-confinement strength model presented higher accuracy as compared with previously proposed models. Finally, an equation is proposed for the predictions of axial load carrying capacity of STFC columns. For the validation of proposed equation, an extensive parametric study is performed using the proposed nonlinear finite element model (FEM). The FEM is calibrated using the load-deflection results of STFC columns from literature. A close agreement was observed between the predictions of proposed finite element model and proposed capacity equation.

Static Load Carrying Capacity in Four Contact Point Slewing Bearings: Theoretical and Preliminary Finite Element Calculations

2010 ◽  
Author(s):  
Josu Aguirrebeitia ◽  
Mikel Abasolo ◽  
Rafael Avile´s ◽  
Igor Fernandez de Bustos ◽  
Rube´n Ansola
Keyword(s):  
Finite Element ◽  
Theoretical Model ◽  
Finite Element Model ◽  
Carrying Capacity ◽  
Static Load ◽  
Contact Point ◽  
Element Model ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Slewing Bearings

This paper presents a theoretical model to calculate the general static load-carrying capacity of four-contact-point slewing bearings under axial, radial and tilting-moment loads, compared with preliminary results obtained from a detailed parametric finite element model of the bearing. The theoretical model is based on a generalization of Sjova¨ll and Rumbarger’s equations and provides an acceptance surface in the load space. The finite element model is based on the modelization of the balls via nonlinear traction-only equivalent spring concept. The aim is to validate the theoretical model to be used as an acceptance curve generator for slewing bearing design.

Stokes Roughness Effects on Hydrodynamic Lubrication. Part I—Comparison Between Incompressible and Compressible Lubricating Films

1986 ◽  
Vol 108 (2) ◽  
pp. 151-158 ◽  
Author(s):  
Y. Mitsuya ◽  
S. Fukui
Keyword(s):  
Carrying Capacity ◽  
Stokes Equations ◽  
Hydrodynamic Lubrication ◽  
Navier Stokes ◽  
Load Carrying Capacity ◽  
Roughness Effects ◽  
Navier Stokes Equations ◽  
Large N ◽  
Significant Difference ◽  
Load Carrying

A perturbation method for the Navier-Stokes equations is presented for analyzing Stokes roughness effects on hydrodynamic lubrication in both incompressible and compressible films. The solution is obtained from direct numerical calculation by using an actual rough spacing, without applying the currently accepted assumption that the roughness height should be small. The roughness wavelength and height influences on flow rate, load carrying capacity and frictional force are clarified. Secondary quantities induced by Stokes effects are found to be proportional to wavenumber n squared for sufficiently large n values, so that the amount of the Stokes effect can be determined by the spacing to wavelength squared ratio. A significant difference between incompressible and compressible films is that Stokes roughness increases the flow resistance of and then enhances the load carrying capacity of incompressible films, while it inversely affects compressible films. The compressibility with respect to secondary pressure induced by the Stokes effects can be neglected for any compressibility number, no matter how large, as long as the local compressibility number, defined by the wavelength, is small.

Effects of Number of Porous Insert, Spindle Speed and Gap Thickness on Characteristics of a Partially Porous Aerostatic Journal Bearing

2015 ◽  
Vol 649 ◽  
pp. 30-37 ◽  
Author(s):  
Te Yen Huang ◽  
Shao Yu Hsu ◽  
Song Chiang Shen ◽  
Sheam Chyun Lin ◽  
Ta Hsin Chou
Keyword(s):  
Carrying Capacity ◽  
Journal Bearing ◽  
Stokes Equations ◽  
Simple Algorithm ◽  
Navier Stokes ◽  
Coupling Scheme ◽  
Load Carrying Capacity ◽  
Navier Stokes Equations ◽  
Rotating Speed ◽  
Load Carrying

The effects of the rotating speed of the spindle, the number of the porous medium inserted into the partially porous aerostatic journal bearing and the thickness of the bearing gap on the characteristics of the bearing such as the pressure distribution, the load carrying capacity and the stiffness of the bearing were studied. Based on the finite volume method and the pressure-velocity coupling scheme of the SIMPLE algorithm with the standard k-ε turbulent model, the CFD software was used to solve the Navier-Stokes equations to calculate the pressure field in the bearing gap. The computed results revealed the faster the spindle rotated, the higher the gap pressure. As the gap thickness increased, the gap pressure, the load carrying capacity and the stiffness of the bearing decreased. The more the porous inserts, the higher the gap pressure and the load carrying capacity, but the less the bearing stiffness would be.

The Validity of the Reynolds Equation in Modeling Hydrostatic Effects in Gas Lubricated Textured Parallel Surfaces

2005 ◽  
Author(s):  
Yuri Feldman ◽  
Yuri Kligerman ◽  
Izhak Etsion ◽  
Shimon Haber
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Stokes Equations ◽  
Surface Texturing ◽  
Laser Surface Texturing ◽  
Navier Stokes ◽  
Load Carrying Capacity ◽  
Navier Stokes Equations ◽  
Load Carrying ◽  
Parallel Surfaces

The pressure distribution and load carrying capacity for a single 3D dimple, representing laser surface texturing (LST) of gas-lubricated tribological components with parallel surfaces, were obtained via two different methods of analysis: 1) a numerical solution of the exact full Navier-Stokes equations; 2) an approximate solution of the much simpler Reynolds equation. Comparison between the two solutions illustrated that the differences in load carrying capacity were negligible for clearances that are 3% or less of the dimple diameter. At larger realistic clearances the error in the load carrying capacity may reach a maximum of 10%.

Sign in / Sign up

Export Citation Format

Share Document