Theoretical and Experimental Analysis of Hydrostatic Thrust Bearings

1960 ◽  
Vol 82 (3) ◽  
pp. 505-511 ◽  
Author(s):  
R. C. Elwell ◽  
B. Sternlicht
Keyword(s):  
Experimental Verification ◽  
Carrying Capacity ◽  
Experimental Analysis ◽  
Load Carrying Capacity ◽  
Constant Flow ◽  
Temperature Changes ◽  
Thrust Bearings ◽  
Flow Restriction ◽  
Load Carrying ◽  
Different Types

This paper presents theoretical and experimental analysis of two types of circular hydrostatic thrust bearings, using incompressible lubricants. Design equations for load-carrying capacity, stiffness, and flow, are given for three different types of flow restriction—orifice, capillary, and constant flow. Experimental verification of the equations is shown. It is seen that each method of restriction imparts its own characteristics on the bearing performance. Constant flow, for instance, results in the stiffest bearing under certain conditions, and capillary restriction is unaffected by temperature changes.

Computational Fluid Dynamics Thermohydrodynamic Analysis of Three-Dimensional Sector-Pad Thrust Bearings With Rectangular Dimples

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
C. I. Papadopoulos ◽  
L. Kaiktsis ◽  
M. Fillon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Carrying Capacity ◽  
Thermal Effects ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Performance Indices ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Texture Design

The paper presents a detailed computational study of flow patterns and performance indices in a dimpled parallel thrust bearing. The bearing consists of eight pads; the stator surface of each pad is partially textured with rectangular dimples, aiming at maximizing the load carrying capacity. The bearing tribological performance is characterized by means of computational fluid dynamics (CFD) simulations, based on the numerical solution of the Navier–Stokes and energy equations for incompressible flow. Realistic boundary conditions are implemented. The effects of operating conditions and texture design are studied for the case of isothermal flow. First, for a reference texture pattern, the effects of varying operating conditions, in particular minimum film thickness (thrust load), rotational speed and feeding oil pressure are investigated. Next, the effects of varying texture geometry characteristics, in particular texture zone circumferential/radial extent, dimple depth, and texture density on the bearing performance indices (load carrying capacity, friction torque, and friction coefficient) are studied, for a representative operating point. For the reference texture design, the effects of varying operating conditions are further investigated, by also taking into account thermal effects. In particular, adiabatic conditions and conjugate heat transfer at the bearing pad are considered. The results of the present study indicate that parallel thrust bearings textured by proper rectangular dimples are characterized by substantial load carrying capacity levels. Thermal effects may significantly reduce load capacity, especially in the range of high speeds and high loads. Based on the present results, favorable texture designs can be assessed.

Influence of water contamination in gear lubricants on wear and micro-pitting performance of case carburized gears

2017 ◽  
Vol 69 (4) ◽  
pp. 612-619 ◽  
Author(s):  
Christian Engelhardt ◽  
Jochen Witzig ◽  
Thomas Tobie ◽  
Karsten Stahl
Keyword(s):  
Carrying Capacity ◽  
Research Work ◽  
Load Carrying Capacity ◽  
Wear Performance ◽  
Content Type ◽  
Effect Of Water ◽  
Base Oils ◽  
Load Carrying ◽  
Different Types ◽  
Influence Of Water

Purpose Water can alter the performance of modern gear lubricants by influencing the flank load carrying capacity of gears significantly. The purpose of this paper is to investigate the influence of water contaminations in different kinds of base oils on the micro-pitting and wear performance of case carburized gears. Design/methodology/approach Concerning micro-pitting and wear, tests, based mostly on the following standardized tests, are performed on a Forschungsstelle fuer zahnraeder und getriebebau (FZG)-back-to-back gear test rig: micro-pitting short test Graufleckenkurztest (GFKT) according to DGMK 575 (screening test), micro-pitting test Graufleckentest (GT) according to FVA 54/7 (load stage test and endurance test) and Slow-speed wear test according to DGMK 377. To investigate the effect of water on the gear load carrying capacity dependent on different types of base oils, two polyglycol oils (PG1 and PG2), a polyalphaolefin oil, a mineral oil and an ester oil E are used. Each of these oils are common wind turbine gear oils with a viscosity ISO VG-220. Additionally, a manual transmission fluid with a viscosity of society of automotive engineers (SAE) 75W-85 is tested. Findings Considering the micro-pitting and wear performance, a significant decrease caused by water contaminations could not be detected. Regarding pitting damages, a generally negative influence was observed. This influence was differently distinctive for different base oil types. Especially non-polar lubricants seem to be affected negatively. The documented damages of the tooth flanks confirm this observation. While typical pitting damages appeared in test runs with polar lubricants, the disruption in test runs with non-polar lubricants was more extensive. Based on the experimental investigations, a general model of the damaging mechanisms of water contaminations in lubricants was derived. It is split into three partitions: interaction lubricant–water (effect of water on the molecular structure of base oils and additives), chemical-material-technological (especially corrosive reactions) and tribological influence (effect of water droplets in the contact zone). It has to be considered that the additive package of lubricants affects the influence of water contaminations on the flank load carrying capacity distinctively. An influence of water on the micro-pitting and wear performance in other than the given lubricants cannot be excluded. Originality/value While former research work was focused more on the effects of water in mineral oils, investigations concerning different types of base oils as well as different types of damages were carried out within this research project.

Density Variation Effects in Stepped-Thrust Bearings

1959 ◽  
Vol 26 (3) ◽  
pp. 337-340
Author(s):  
C. F. Kettleborough
Keyword(s):  
Coefficient Of Friction ◽  
Carrying Capacity ◽  
Thrust Bearing ◽  
Density Variation ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Load Carrying ◽  
The Coefficient Of Friction

Abstract The problem of the stepped-thrust bearing is considered but, whereas normally volumetric continuity is assumed, the equations are solved assuming mass continuity; i.e., the variation of density is also considered as well as the effect of the stepped discontinuity on the load-carrying capacity and the coefficient of friction. Computed theoretical curves illustrate the importance of the density on the operation of this bearing and, in part, explain results already published.

The limiting load-carrying capacity of foil thrust bearings

2017 ◽  
Vol 232 (8) ◽  
pp. 1046-1052
Author(s):  
P Samanta ◽  
MM Khonsari
Keyword(s):  
Analytical Solution ◽  
Carrying Capacity ◽  
Simple Procedure ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Limiting Load ◽  
Load Carrying ◽  
Closed Form Analytical Solution ◽  
Foil Thrust Bearing ◽  
Thrust Load

A simple procedure is proposed for predicting the limiting pressure and corresponding limiting of the load-carrying capacity of a foil thrust bearing. A closed-form analytical solution for the limiting load is derived, and the predictions are verified by the numerical solution. An approximate solution for limiting thrust load is also obtained and compared to the value obtained through the analytical solution. A parametric analysis is performed to examine the dependency of the limiting load on different geometric parameters for the bearing.

Geometry Optimization of Textured Three-Dimensional Micro- Thrust Bearings

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
C. I. Papadopoulos ◽  
E. E. Efstathiou ◽  
P. G. Nikolakopoulos ◽  
L. Kaiktsis
Keyword(s):  
Carrying Capacity ◽  
Stokes Equations ◽  
Load Capacity ◽  
Three Dimensional ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Micro Channels ◽  
Wide Range ◽  
Load Carrying ◽  
Bearing Load

This paper presents an optimization study of the geometry of three-dimensional micro-thrust bearings in a wide range of convergence ratios. The optimization goal is the maximization of the bearing load carrying capacity. The bearings are modeled as micro-channels, consisting of a smooth moving wall (rotor), and a stationary wall (stator) with partial periodic rectangular texturing. The flow field is calculated from the numerical solution of the Navier-Stokes equations for incompressible isothermal flow; processing of the results yields the bearing load capacity and friction coefficient. The geometry of the textured channel is defined parametrically for several width-to-length ratios. Optimal texturing geometries are obtained by utilizing an optimization tool based on genetic algorithms, which is coupled to the CFD code. Here, the design variables define the bearing geometry and convergence ratio. To minimize the computational cost, a multi-objective approach is proposed, consisting in the simultaneous maximization of the load carrying capacity and minimization of the bearing convergence ratio. The optimal solutions, identified based on the concept of Pareto dominance, are equivalent to those of single-objective optimization problems for different convergence ratio values. The present results demonstrate that the characteristics of the optimal texturing patterns depend strongly on both the convergence ratio and the width-to-length ratio. Further, the optimal load carrying capacity increases at increasing convergence ratio, up to an optimal value, identified by the optimization procedure. Finally, proper surface texturing provides substantial load carrying capacity even for parallel or slightly diverging bearings. Based on the present results, we propose simple formulas for the design of textured micro-thrust bearings.

Experimental Verification of Glass-Fibre-Concrete Covers of Footbridge Deck Cornice, Subjected to Wind Loading Actions

2014 ◽  
Vol 590 ◽  
pp. 363-367 ◽  
Author(s):  
Marcela Karmazínová ◽  
Jindrich Melcher ◽  
Michal Štrba
Keyword(s):  
Glass Fibre ◽  
Experimental Verification ◽  
Carrying Capacity ◽  
Wind Loading ◽  
Load Carrying Capacity ◽  
Fibre Concrete ◽  
Load Carrying

The paper summarizes the results and evaluation of tests of the resistance of glass-fibre-concrete components used for footbridge deck cover subjected to wind loading actions. The main aims of this research was not only to verify the objective load-carrying capacity and serviceability of covering panels, but also to verify the use of glass-fibre-concrete and its properties, if applied for non-typical product. The tests also show the usage of the unique and effective method of the vacuum loading. The research has been elaborated based on the requirements of DAKO Brno Ltd. Company.

Tribology of Lubricants

2021 ◽  
pp. 391-420
Keyword(s):  
Service Life ◽  
Tribological Properties ◽  
Carrying Capacity ◽  
Solid Lubricants ◽  
Load Carrying Capacity ◽  
Friction Control ◽  
Load Carrying ◽  
Different Types ◽  
Traction Fluids ◽  
The Relationship

Abstract This chapter covers the tribological properties of different types of oil, greases, solid lubricants, and metalworking and traction fluids. It explains how lubricants are made, how they work, and how they are applied and tested. It also discusses the fundamentals of lubrication and friction control, the relationship between viscosity and breakaway friction, and the factors that affect load-carrying capacity and service life.

Analysis of shear behavior between old concrete and fiber concrete

2021 ◽  
Author(s):  
Martin Vavruš ◽  
Peter Koteš ◽  
František Bahleda ◽  
Jozef Jošt
Keyword(s):  
Carrying Capacity ◽  
Research Work ◽  
Concrete Structures ◽  
Mechanical Damage ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Fiber Concrete ◽  
Different Types ◽  
Thawing And Freezing Cycles

AbstractConcrete structures that are influenced by degradation, overloading, the thawing, and freezing cycles, corrosion of reinforced bars, should be repaired or strengthened. Each of the mentioned influences lead to decreased load-carrying capacity of the structure or its member. Exceeding the load-carrying capacity leads to mechanical damage of members or excessive deformation. The damaged member has to be strengthened to the required level of reliability and load-carrying capacity. There exist many types and methods of strengthening the columns. This research work deals with strengthening of columns by concreting a new layer of fiber concrete. When applying that type of strengthening, it is necessary to assure the contact between the old layer and the new one. The paper deals with analysis of different types of contacts and determination of their parametric values.

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