scholarly journals Ways to Improve Wear Resistance and Damping Properties of Radial Bearings Taking into Account Inertial Forces

2021 ◽  
Vol 2096 (1) ◽  
pp. 012105
Author(s):  
V N Bagrova ◽  
I A Kolobov
Keyword(s):  
Electric Conductivity ◽  
Friction Force ◽  
Carrying Capacity ◽  
Field Vector ◽  
Porous Coating ◽  
Stable Operation ◽  
Design Calculation ◽  
Infinite Length ◽  
Inertial Forces ◽  
Incomplete Filling

Abstract This article considers a radial sliding bearing of infinite length whose moving part consists of the support, the porous layer, and the liquid lubricant. The analysis of the existing design calculation methods for such sliding bearings shows that they are very approximate because they do not consider the inertial forces applied, the electric conductivity of the lubricant, the permeability anisotropy, as well as the impacts of the electric field vector, magnetic induction vector, and incomplete filling of the working gap (pre-accident condition). The authors demonstrate how these factors impact the stable operation of the device facilitating the hydrodynamic regime. The authors find the asymptotic solution for the zero, first, and second approximation taking into account the inertial forces for the “thin layer”. By solving the produced equations using the Gauss-Seidel method, the authors determine the key operating parameters of the friction couple in question: the carrying capacity and the friction force. The authors provide an impact assessment for the parameters characterizing the permeability of the porous coating, the electric conductivity, and viscosity of the lubricant, as well as the length of the loaded area and the impacts of inertial forces on the carrying capacity and the friction force.

THRESHOLDS, NICHES AND INERTIA: ENTREPRENEURIAL OPPORTUNITIES IN THE STEAMSHIP INDUSTRY

2012 ◽  
Vol 20 (04) ◽  
pp. 379-404 ◽  
Author(s):  
GREG CLYDESDALE
Keyword(s):  
Carrying Capacity ◽  
Higher Order ◽  
Inertial Forces ◽  
Complex Relationship ◽  
Entrepreneurial Opportunity ◽  
Entrepreneurial Opportunities ◽  
Business Opportunities ◽  
Time Variations ◽  
Niche Formation ◽  
Over Time

This paper seeks to increase understanding of the role the environment in the emergence of business opportunities, and how opportunities change as industries evolves. It explores the dynamics of entrepreneurial opportunity in the British steamship industry. It suggests niches are created when environmental thresholds are reached. Entrepreneurs who act before thresholds are reached fail. A complex relationship between inventors, innovators/entrepreneurs and higher order opportunities is revealed illustrating the difficulty of identifying 'higher order opportunities. Over time, variations in environmental forces changed niche size and carrying capacity. Causes of new niche formation were both exogenous and endogenous supporting both Kirzner and Schumpeter. Inertial forces inhibited the ability of existing players to seize opening niches and expanded opportunities for new comers.

Theoretical Model for the Optimal Design of Surface Texturing on Piston Compression Ring

2015 ◽  
Vol 787 ◽  
pp. 327-331
Author(s):  
S. Prakash ◽  
G. Nagarajan
Keyword(s):  
Theoretical Model ◽  
Friction Force ◽  
Carrying Capacity ◽  
Piston Ring ◽  
Surface Texturing ◽  
Cylinder Liner ◽  
Load Carrying Capacity ◽  
Compression Ring ◽  
Load Carrying ◽  
Micro Dimples

A Theoretical model was developed to study the potential use of surface texturing for reducing the friction between a piston ring and cylinder liner. The model can predict the load-carrying capacity and friction force of the piston compression ring from Reynolds equation. The investigation is carried out using different dimple depths as well as different dimple diameters. Micro-dimples on the piston ring were able to generate significant hydrodynamic support. Numerical results show that surface texturing can decrease the friction force and extend the load-carrying capacity. The optimum surface texturing parameters such as dimples depth and dimples diameter were found.

A Demonstrably Optimum One Dimensional Journal Bearing

1972 ◽  
Vol 94 (2) ◽  
pp. 188-192 ◽  
Author(s):  
S. M. Rohde
Keyword(s):  
Film Thickness ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Infinite Length ◽  
Load Carrying Capacity ◽  
One Dimensional ◽  
Load Carrying ◽  
Minimum Film Thickness ◽  
Constant Viscosity ◽  
Nonlocal Formulation

By the use of a new variational technique, the bearing profile which maximizes the load carrying capacity of an infinite length journal bearing is obtained. The lubricant is assumed to be incompressible and of constant viscosity. The flow is assumed to be laminar and the optimization is based upon a minimum film thickness. The solution obtained is a concentric step bearing with a film thickness ratio of 1.812 and a ridge to pad ratio of 0.328. It is mathematically shown by the use of the “nonlocal” formulation that this step profile does yield a maximum among all profiles sufficiently “close.”

scholarly journals The process of increasing the stable operation of the working body in crank presses

2020 ◽  
Vol 164 ◽  
pp. 03017 ◽  
Author(s):  
Kirill Kobzev ◽  
Yuliya Goncharova ◽  
Nataliya Kobzeva
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Frictional Contact ◽  
Load Capacity ◽  
Maximum Load ◽  
Necessary Condition ◽  
Stable Operation ◽  
Friction Contact ◽  
Maximum Function ◽  
Full Load

The article considers the study of the synthesized concept of frictional contact of solids in crank presses. As a result of the analysis the possibility of obtaining the maximum load characteristic of the friction contact within the interval of variation of the friction coefficient has been established. The possibility of equality of the values of the friction force of the friction contact at the boundaries of the indicated interval in the presence of a maximum and the achievement of their greatest stability under these conditions is also revealed. As result the upgraded concept of frictional contact allows theoretically to obtain a very high stability of the friction force, however, due to the relatively large value of the angle and force parameter, it is used inefficiently. A necessary condition for the absence of zero reversal of the output parameter of the main friction group of the friction contact in the interval of variation of the friction coefficient and the presence of the maximum function of the load capacity of the friction contact is the transfer of its full load by the sensitive elements of the additional friction group. An additional condition for the existence of a maximum is the need for the sensitive elements of the main friction group to transfer part of its full load at an equal number of friction pairs of both friction groups, and for the sensitive elements to transfer the full load of the main friction group at a lower number of friction pairs than in the additional friction group.

scholarly journals Computational model of a micropolar lubricant with a non-standard support profile and a metal coating at incomplete filling of the working gap

2021 ◽  
Vol 2061 (1) ◽  
pp. 012037
Author(s):  
G D Vernigora ◽  
E V Kruchinina ◽  
M A Mukutadze
Keyword(s):  
Bearing Capacity ◽  
Rheological Properties ◽  
Friction Force ◽  
Friction Pair ◽  
Mechanical Energy ◽  
Metal Alloy ◽  
Metal Coating ◽  
Flow Mode ◽  
Operating Characteristics ◽  
Incomplete Filling

Abstract The authors propose an asymptotic and exact self-similar solution for zero (without considering the melt) and the first (considering the melt) approximation of a wedge-shaped sliding support with a profile adapted to friction and a fusible metal coating of the guide surface. The solution is based on the equation of a micropolar liquid flow for a “thin layer”, the continuity equation, as well as the equation describing the profile of the molten contour of a guide coated with a fusible metal alloy. The authors have taken into account the formula of the rate of mechanical energy dissipation as well as rheological properties of the lubricant and the melt, which have micropolar properties in the laminar flow mode at incomplete filling of the working gap. Analytical dependences have been obtained for the profile of the molten surface of the guide coated with a low-melting metal alloy, as well as for the velocity and pressure fields at zero and first approximation. In addition, the main operating characteristics of the friction pair under consideration have been determined: the bearing capacity and the friction force. The article contains estimation of the influence of the parameters conditioned by coating melt and adapted to the friction conditions of the support profile, and the parameter characterizing the rheological properties of the lubricant, as well as the length of the loaded area in terms of bearing capacity and friction force.

scholarly journals Comparative study of spherical dimple and bump effects on the tribological performances of journal bearing

2018 ◽  
Vol 233 (1) ◽  
pp. 139-157 ◽  
Author(s):  
Chao Gui ◽  
Fanming Meng
Keyword(s):  
Friction Force ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Hydrodynamic Pressure ◽  
Load Carrying Capacity ◽  
Transform Method ◽  
Cavitation Effect ◽  
Fast Fourier Transform Method ◽  
Load Carrying

In the present study, tribological performances of journal bearings with the representative spherical dimples and bumps are compared numerically. In doing so, the hydrodynamic pressure of the lubricant is solved by the Reynolds equation considering the lubricant cavitation effect. Meanwhile, the elastic deformation is calculated by the continuous convolution fast Fourier transform method. The enhanced load-carrying capacity and the reduced friction force occur only when the dimples are located at pressure rising part of the bearing. The bumps located at the pressure falling part can enhance the load-carrying capacity but increase the friction force. The above dimple and bump effects change at the varied feature sizes and intervals.

The Spatial Motion of a Compliantly Suspended Rigid Body Constrained by Multi-Point Frictional Contact

2003 ◽  
Author(s):  
Shuguang Huang ◽  
Joseph M. Schimmels
Keyword(s):  
Rigid Body ◽  
Friction Force ◽  
Coulomb Friction ◽  
Frictional Contact ◽  
The Body ◽  
Elastic Behavior ◽  
Inertial Forces ◽  
Spatial Motion ◽  
Frictional Surfaces

This paper addresses methods for determining the motion of an elastically suspended rigid body interacting with frictional surfaces at multiple locations. The methods developed assume: 1) that the motion of the base from which the body is suspended and the elastic behavior of the suspension are known, 2) that inertial forces are negligible (motion is quasi-static), and 3) that the interaction is characterized by Coulomb friction. The derived coupled sets of spatial rigid body equations are used to determine both the unknown direction of the friction force (at each point of contact) and the unknown motion of the rigid body.

scholarly journals Mathematical model of a ferromagnetic lubricant in the presence of a porous coating in the bearing structure

2021 ◽  
Vol 2061 (1) ◽  
pp. 012038
Author(s):  
A N Opatskikh ◽  
M V Novakovich
Keyword(s):  
Bearing Capacity ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Flow Equation ◽  
Porous Coating ◽  
Operating Characteristics ◽  
Support Ring ◽  
Liquid Lubricant ◽  
Incomplete Filling ◽  
The Coefficient Of Friction

Abstract Based on the flow equation of a ferromagnetic liquid lubricant for a “thin layer”, the continuity equation and Darcy’s equation describing the flow of a lubricant in a porous body, an exact self-similar solution of wedge-shaped sliding support with a porous coating of the surface of the support ring is found, taking into account the dependence of the viscosity of the ferromagnetic lubricant and the permeability of the porous coating with the incomplete filling of the working gap. Analytical dependencies for the velocity and pressure fields in the lubricating and porous layer are obtained. Also, the main operating characteristics are determined load-bearing capacity and friction force. The numerical analysis of the theoretical results showed that the bearing capacity of the bearings can be increased by 8-12% in the range of the studied load-speed modes. At the same time, the coefficient of friction is reduced by 14-16%. To verify and confirm the effectiveness of the obtained theoretical models, an experimental study of a modified wedge-shaped sliding support on TP-22C, MS-20 oil and their mixture with various additives was carried out. As a result of theoretical and experimental studies, tribotechnical characteristics were determined that allow us to judge the presence of a long-term friction mode.

THE ANALYSIS OF HYDRODYNAMIC PRESSURE DISTRIBUTION AND LOAD CARRYING CAPACITY IN THE GAP OF SLIDE JOURNAL BEARINGS WITH MICRO-GROOVES

Tribologia ◽  
2018 ◽  
Vol 272 (2) ◽  
pp. 119-126
Author(s):  
Andrzej MISZCZAK
Keyword(s):  
Friction Force ◽  
Carrying Capacity ◽  
Hydrodynamic Pressure ◽  
Load Carrying Capacity ◽  
Isothermal Model ◽  
Slide Bearing ◽  
Flow Parameters ◽  
Load Carrying ◽  
Wrap Angle ◽  
Research Show

The purpose of this paper is to analyse the distribution of hydrodynamic pressure, load carrying capacities, and friction force in the gap of the slide bearing on account of the type, number, and size of micro-grooves on the surface of the sleeve. It was assumed that micro-grooves were distributed equally on the circumference of the sleeve as well as parallel to its axis. Micro-bearings with micro-grooves are more and more often utilized in the technical applications, e.g., in HDD disks or in computer fans. It is advisable to carry out a numerical analysis on the influence of the number and the size of micro-grooves on the value of the basic flow parameters in the slide micro-bearing. A laminar flow of lubricating fluid and an isothermal model of the lubrication of the slide bearing was used for the analysis. A classical Newtonian model was applied as the constitutive equation. A cylindrical slide bearing with the finished length and smooth sleeve, and a full wrap angle was used for the research. The density and thermal conductivity of the oil were considered to be constant in the thin film of oil. The results of measurements of shape and sizes of micro-grooves in real micro-slide bearings were presented by the author in the previous publications. The results of that research are used at present to determine the preliminary assumptions concerning the shape and the size of the micro-grooves. The results obtained in the research show the minor influence of micro-grooves on the value of the friction force and a few percentages rate influence of micro-grooves on the value of load carrying capacity.

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