The Additive Ep-Condition and the Critical Scuffing Limit for Rolling-Sliding

1996 ◽  
Vol 118 (1) ◽  
pp. 125-130 ◽  
Author(s):  
Enrique F. Escobar-Jaramillo
Keyword(s):  
Friction Coefficient ◽  
Calculation Method ◽  
Load Capacity ◽  
Integral Relation ◽  
Simple Calculation ◽  
Friction Contact ◽  
Predictive Capability ◽  
Free Case ◽  
Implicit Dependence ◽  
Ep Additive

This paper introduces a new model for the scuffing load capacity in heavily loaded contacts, concerned specifically with the effects of EP-additive oils. The scuffing limit for the additive condition will be closely related to the initial additive-free case, using the calculation method of Blok, solely on a referential level. The process thermodynamics involved at a friction contact will be related to a phenomenological integral relation, containing the necessary internal coordinate to describe the implicit dependence of the friction coefficient with time. The experimental response of the friction contact depends on a relaxant friction coefficient due to the additive effect. The simple calculation method requires only three input parameters for the prediction of the scuffing limit, and these can be obtained from a few experimental scuffing tests. All the tribology of the present scuffing model can be considered to be contained in a simple linear relationship, with the sliding speed as the dominant variable. The calculation criterion has shown to have predictive capability which agrees well with experiments.

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.

Fire resistance of partially encased composite columns subjected to eccentric loading

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abdelkadir Fellouh ◽  
Abdelkader Bougara ◽  
Paulo Piloto ◽  
Nourredine Benlakehal
Keyword(s):  
Bearing Capacity ◽  
Thermal Behaviour ◽  
Analytical Method ◽  
Calculation Method ◽  
Load Capacity ◽  
Simple Calculation ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Content Type ◽  
Composite Column

PurposeInvestigate the fire performance of eccentrically loaded concrete partially encased column (PEC), using the advanced calculation method (ANSYS 18.2, 2017) and the simple calculation method in Annex G of Eurocode 4 (EN 1994-1-2, 2005). This work examines the influence of a range of parameters on fire behaviour of the composite column including: eccentricity loading, slenderness, reinforcement, fire rating and fire scenario. In this study, ISO-834 (ISO834-1, 1999) was used as fire source.Design/methodology/approachCurrently, different methods of analysis used to assess the thermal behaviour of composite column exposed to fire. Analytical method named simplified calculation methods defined in European standard and numerical simulations named advanced calculation models are treated in this paper.FindingsThe load-bearing capacity of the composite column becomes very weak in the presence of the fire accident and eccentric loading, this recommends to avoid as much as possible eccentric loading during the design of construction building. The reinforcement has a slight influence on the temperature evolution; moreover, the reinforcement has a great contribution on the load capacity, especially in combined compression and bending. When only the two concrete sides are exposed to fire, the partially encased composite column presents a high load-bearing capacity value.Originality/valueThe use of a three-dimensional numerical model (ANSYS) allowed to describe easily the thermal behaviour of PEC columns under eccentric loading with the regard to the analytical method, which is based on three complex steps. In this study, the presence of the load eccentricity has found to have more effect on the load-bearing capacity than the slenderness of the composite column. Introducing a load eccentricity on the top of the column may have the same a reducing effect on the load-bearing capacity as the fire.

A Simple Calculation Method of Flashover Characteristics for Long Air Gaps under Various Discharge Conditions

1993 ◽  
Vol 113 (3) ◽  
pp. 252-258
Author(s):  
Kiyoto Nishijima ◽  
Itaru Tsuneyasu ◽  
Hiraku Nakahodo ◽  
Masaharu Minakami
Keyword(s):  
Calculation Method ◽  
Simple Calculation ◽  
Air Gaps

Tribological performance of a surface textured meso scale air bearing

2019 ◽  
Vol 72 (5) ◽  
pp. 599-609
Author(s):  
Nilesh D. Hingawe ◽  
Skylab P. Bhore
Keyword(s):  
Friction Coefficient ◽  
Journal Bearing ◽  
Load Capacity ◽  
Tribological Performance ◽  
Design Parameters ◽  
Content Type ◽  
Thin Film Model ◽  
Maximum Improvement ◽  
Meso Scale ◽  
Texture Design

Purpose The purpose of this study is to improve the tribological performance of meso scale air journal bearing by adopting texture on the bearing surface. Design/methodology/approach The present study is based on numerical analysis. The detailed numerical investigation is carried out using a fluid flow based thin-film model in COMSOL 5.2 software. Findings The influence of texture design parameters: geometry (shape, orientation and slender ratio), and position on the tribological performance of meso scale air journal bearing is investigated. It is found that texture shape has a strong influence on the tribological characteristics such as load capacity and friction coefficient of the bearing. Slender texture improves the load capacity, but it has a negligible effect on the reduction of friction coefficient. In contrast, texture orientation is found to be insignificant for both increasing load capacity and decreasing friction coefficient. Furthermore, the maximum improvement in load capacity is obtained for partially textured bearing, but the minimum friction coefficient is achieved for full texturing. Originality/value The present study investigates the influence of texture design parameters viz geometry (shape, orientation and slender ratio), and position on the tribological performance of meso scale air journal bearing.

A simple calculation method for estimating the flow velocity on the roof of a train running through a tunnel using an unsteady incompressible flow model

2019 ◽  
Vol 234 (7) ◽  
pp. 734-748
Author(s):  
Katsuhiro Kikuchi ◽  
Satoru Ozawa ◽  
Yuhei Noguchi ◽  
Shinya Mashimo ◽  
Takanobu Igawa
Keyword(s):  
Boundary Layer ◽  
Flow Velocity ◽  
Calculation Method ◽  
Model Experiment ◽  
Flow Model ◽  
Simple Calculation ◽  
Dimensional Model ◽  
One Dimensional ◽  
Calculation Results ◽  
Tunnel System

Predicting the aerodynamic phenomena in a train-tunnel system is important for increasing the speed of railway trains. Among these phenomena, many studies have focused on the effects of pressure; however, only a few studies have examined the effects of flow velocity. When designing train roof equipment such as a pantograph and an aerodynamic braking unit, it is necessary to estimate the flow velocity while considering the influence of the boundary layer developed on the train roof. Until now, numerical simulations using a one-dimensional model have been utilized to predict the flow velocity around a train traveling through a tunnel; however, the influence of the boundary layer cannot be taken into consideration in these simulations. For this purpose, the authors have previously proposed a simple calculation method based on a steady incompressible tunnel flow model that can take into account the influence of the boundary layer, but this method could not incorporate the unsteadiness of the flow velocity. Therefore, in this study, the authors extend the previous simple calculation method such that it can be used for an unsteady incompressible tunnel flow. The authors compare the calculation results obtained from the extended method with the results of a model experiment and a field test to confirm its effectiveness.

Effect of non-Newtonian magneto-elastohydrodynamic on performance characteristics of slider-bearings

2019 ◽  
Vol 71 (10) ◽  
pp. 1158-1165
Author(s):  
Mouhcine Mouda ◽  
Mohamed Nabhani ◽  
Mohamed El Khlifi
Keyword(s):  
Friction Coefficient ◽  
Design Methodology ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Transverse Magnetic ◽  
Finite Width ◽  
Two Dimensional ◽  
Content Type ◽  
Slider Bearings ◽  
First Time

Purpose This study aims to examine the magneto-elastohydrodynamic effect on finite-width slider-bearings lubrication using a non-Newtonian lubricant. Design/methodology/approach Based on the magneto-hydrodynamic (MHD) theory and Stokes micro-continuum mechanics, the modified two-dimensional Reynolds equation including bearing deformation was derived. Findings It is found that the bearing deformation diminishes the load-capacity and increases the friction coefficient in comparison with the rigid case. However, the non-Newtonian effect increases load-capacity but decreases the friction coefficient. Moreover, the use of a transverse magnetic field increases both the friction coefficient and load capacity. Originality/value This study combines for the first time MHD and elastic deformation effects on finite-width slider-bearings using a non-Newtonian lubricant.

Static characteristics of misaligned multiple axial groove water-lubricated bearing in the turbulent regime

2016 ◽  
Vol 231 (3) ◽  
pp. 385-398 ◽  
Author(s):  
Ravindra Mallya ◽  
Satish B Shenoy ◽  
Raghuvir Pai
Keyword(s):  
Reynolds Number ◽  
Friction Coefficient ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Load Capacity ◽  
Turbulent Regime ◽  
Load Carrying Capacity ◽  
Static Characteristics ◽  
Load Carrying ◽  
Turbulence Effects

The static characteristics of misaligned three-axial water-lubricated journal bearing in the turbulent regime are analyzed for groove angles 36° and 18°. Ng and Pan’s turbulence model is applied to study the turbulence effects in the journal bearing. The static parameters such as load-carrying capacity, friction coefficient, and side leakage are found for different degree of misalignment (DM). The change in flow regime of the lubricant from laminar to turbulent and the increase in misalignment, improved the load capacity of the bearing. For lightly loaded bearings, the friction coefficient of the bearing increased with the increase in Reynolds number.

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