Tribological design of hydrodynamic sliding journal bearings – formulating new functional charts

2005 ◽  
Vol 57 (1) ◽  
pp. 4-11 ◽  
Author(s):  
C. Pandazaras ◽  
G. Petropoulos
Keyword(s):  
Design Methodology ◽  
Reynolds Equation ◽  
Journal Bearings ◽  
Content Type ◽  
Topographic Features ◽  
Operational Characteristics ◽  
Innovative Methodology ◽  
Limited Length ◽  
New Type

PurposeThis paper aims to introduce an innovative methodology for the determination of operational characteristics of journal bearings (j‐bs) through using new type charts based upon a numerical solution of the Reynolds equation.Design/methodology/approachThe present paper proposes the mapping of the behaviour of a smooth, isothermal and hydrodynamic (j‐b) as a first step towards a future representation of the behaviour of j‐b's with limited length and high lubricating clearance with or without macro or micro topographic features operating under high loads, high temperatures and low linear velocities leading to conditions of mixed or boundary lubrication.FindingsThe derived analytical relationships between dimensionless quantities lead to the development of high precision synthetic operational charts regarding sliding j‐b of any given geometry and varying operational characteristics.Originality/valueBy considering the iso‐operational curves which are of a hook form relevant to comparative data becomes directly and rapidly clarified.

Restrictor-based studies of hybrid hole-entry conical journal bearings

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Prashant G. Khakse ◽  
Vikas M. Phalle
Keyword(s):  
Numerical Simulation ◽  
Design Methodology ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Constant Flow ◽  
Hybrid Mode ◽  
Content Type ◽  
Conical Bearing ◽  
Flow Valve

Purpose This paper aims to describe how successfully a particular restrictor delivers its best in increasing the conical journal bearing performance. The restrictors are used in the hole-entry conical journal bearing subjected to hybrid mode. Thus, the restrictors, like constant flow valve (CFV), orifice and capillary, are studied comparatively. Design/methodology/approach Numerical simulation for the bearing results with the three restrictors are obtained by using finite element method (FEM) under the well-known modified Reynolds equation. Findings When the hole-entry conical journal bearings, with the restrictor design parameter range C¯s2 = 0.03 – 0.09, are operated, the results obtained are quite distinctive and significant. It indicates that the CFV restrictor-based conical bearing gives enhanced performance in comparison to orifice and capillary restrictors. Moreover, it suggests the performance-wise sequence of the restrictors in hybrid bearings as CFV > Orifice > Capillary. Originality/value The outcome of the research paper will give insight to help the bearing designer to choose the particular restrictor in hybrid conical bearing depending on the industrial need.

Locating complex eigenvalues for analytical eddy-current models used to detect flaws

2019 ◽  
Vol 38 (6) ◽  
pp. 1800-1809
Author(s):  
Grzegorz Tytko ◽  
Łukasz Dawidowski
Keyword(s):  
Eddy Current ◽  
Design Methodology ◽  
Complex Function ◽  
Precise Determination ◽  
Argument Principle ◽  
Content Type ◽  
Conductive Material ◽  
Complex Roots ◽  
Complex Eigenvalues

Purpose Discrete eigenvalues occur in eddy current problems in which the solution domain was truncated on its edge. In case of conductive material with a hole, the eigenvalues are complex numbers. Their computation consists of finding complex roots of a complex function that satisfies the electromagnetic interface conditions. The purpose of this paper is to present a method of computing complex eigenvalues that are roots of such a function. Design/methodology/approach The proposed approach involves precise determination of regions in which the roots are found and applying sets of initial points, as well as the Cauchy argument principle to calculate them. Findings The elaborated algorithm was implemented in Matlab and the obtained results were verified using Newton’s method and the fsolve procedure. Both in the case of magnetic and nonmagnetic materials, such a solution was the only one that did not skip any of the eigenvalues, obtaining the results in the shortest time. Originality/value The paper presents a new effective method of locating complex eigenvalues for analytical solutions of eddy current problems containing a conductive material with a hole.

Fraud and counterfeit wines in France: an overview and perspectives

2017 ◽  
Vol 119 (1) ◽  
pp. 84-104 ◽  
Author(s):  
Benoit Lecat ◽  
Joelle Brouard ◽  
Claude Chapuis
Keyword(s):  
Media Coverage ◽  
Design Methodology ◽  
Modern Technology ◽  
Wine Industry ◽  
Technological Changes ◽  
Content Type ◽  
New Type ◽  
Technical Solutions ◽  
Official Data ◽  
Practical Implications

Purpose The purpose of this paper is to analyze the specificities of wine forgery today and to show the perspectives offered to the different stakeholders in the wine industry. Design/methodology/approach Owing to the technical aspects of this paper, a literature review based on academic papers (history) and articles coming from the professional press, internet websites and public organizations was made. Findings It was found that frauds have always existed. Forgers are constantly in search of new ways of counterfeiting wines. Producers have had to adapt to the various forms of counterfeiting, mainly by resorting to modern technology. As the traceability of great wines is becoming crucial, a new type of relationships between producers anxious to offer genuine estate wines and consumers anxious to drink the bottles they ordered has developed. This new constraint became a marketing opportunity for producers. Research limitations/implications It was difficult to obtain official data (interviews or surveys) because of the sensitiveness of the topic. Practical implications This paper, which offers an inventory of the methods used by forgers to deceive customers, makes both producers and consumers aware of the extent of the problem. The counterfeiting phenomenon is dangerous for producers’ image and the technological changes are a tool allowing producers to protect their wine and reinforce their relationships with consumers. Originality/value This paper gives an overview of forgers’ ploys in France. It opens a discussion about perspectives for the different stakeholders while most of the research tends to focus on technical solutions and the analysis of specific affairs which received media coverage.

Causality in qualitative market and social research

2019 ◽  
Vol 22 (3) ◽  
pp. 405-413
Author(s):  
Clive Roland Boddy
Keyword(s):  
Qualitative Research ◽  
Design Methodology ◽  
Social Research ◽  
Pragmatic Approach ◽  
Social Phenomena ◽  
Content Type ◽  
The Past ◽  
The Moment ◽  
Practical Implications

Purpose Academic qualitative researchers have been criticized for rejecting the idea that their research can establish causality while market and social researchers, with their realist and pragmatic approach to research, take for granted that it can. This paper aims to explore the ability of qualitative research to determine cause and effect in terms of market and social phenomena. Design/methodology/approach The literature on causality in qualitative research is reviewed and discussed. The discussion is further informed by the author’s own experience of undertaking commercial and academic market and social qualitative research over the past 33 years. Findings In qualitative market and social research, the determination of causality is often needed but rarely discussed. This paper explores this occurrence and brings to the fore, via discussion and the use of example, the ways in which causality can be determined by qualitative research. Practical implications A determination of what events bring about predictable changes in social and market environments can be established via qualitative research particularly at a probabilistic level of causality. This implies that policymakers should give a greater emphasis to qualitative findings than then sometimes do at the moment. Originality/value Causality in market and social research is rarely discussed by practitioners but is nevertheless a premise of much of the qualitative research that is undertaken. This paper is therefore distinctive in that it examines whether this premise is justifiable.

Local on-demand fabrication: microfactories and online manufacturing platforms

2020 ◽  
Vol 32 (1) ◽  
pp. 20-41
Author(s):  
Jose Orlando Montes ◽  
F. Xavier Olleros
Keyword(s):  
Design Methodology ◽  
Content Type ◽  
On Demand ◽  
Online Platforms ◽  
Machine Shops ◽  
Multiple Case ◽  
New Type ◽  
Experiential Research ◽  
Practical Implications

PurposeThis article explores a particular on-demand fabrication unit, the microfactory (MF). It identifies and contrasts several MFs and proposes a taxonomy. This research also explores online manufacturing platforms (OMP) that complement certain MFs.Design/methodology/approachThis research implements a multiple case study (71 cases in 21 countries), triangulating data available on the web with interviews, virtual/physical tours and experiential research.FindingsThe results suggest that automation and openness are the main dimensions that differentiate the MFs. Using these dimensions, a taxonomy of MFs is created. MFs with relatively low automation and high openness tend to be innovation-driven microfactories (IDMFs). MFs with high automation and low openness levels tend to be customization-driven microfactories (CDMFs). And MFs with relatively low automation and low openness tend to be classic machine shops (MSs). There are two types of OMP: closed (COMPs) and multisided (MOMPs). MOMPs can be low-end or high-end.Practical implicationsIn a world where online platforms are becoming central to the reinvention of manufacturing, multisided online platforms and small fabricators will become strongly symbiotic.Originality/valueThis paper offers a clearer conceptualization of MFs and OMPs, which may help to better understand the reality of local on-demand fabrication. Moreover, it explores a new type of experiential research, which tries to describe and interpret firms through transactional activities. Many details of a firm that are difficult to capture via interviews and netnography can be revealed this way.

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.

Study of the metrological characteristics of the hydrostatic pressure sensor

Sensor Review ◽  
2019 ◽  
Vol 39 (5) ◽  
pp. 665-669
Author(s):  
Igor S. Nadezhdin ◽  
Aleksey G. Goryunov ◽  
Yuri G. Svinolupov ◽  
Olga J. Zadorozhnaya
Keyword(s):  
Hydrostatic Pressure ◽  
Pressure Sensor ◽  
Measurement Errors ◽  
Design Methodology ◽  
Content Type ◽  
Sensor Model ◽  
Operational Characteristics ◽  
Calibration Algorithm ◽  
The Mathematical Model ◽  
Maximum Minimum

Purpose The purpose of this paper is to develop a digital hydrostatic pressure sensor with the required metrological and operational characteristics. The developed sensor is designed to control hydrostatic pressure in wells during various geophysical works and studies. Design/methodology/approach To obtain the required metrological and operational characteristics of the sensor, a method was developed and applied to reduce the measurement error based on the calibration algorithm and the sensor model. Findings By using the developed calibration algorithm and the mathematical model of the sensor, it was possible to compensate for the measurement errors of the hydrostatic pressure sensor. Originality/value In the course of this research, tests of the developed sensor were carried and the maximum/minimum of measurement result errors was determined.

Behaviour of two-lobe hole-entry hybrid journal bearing system under the combined influence of textured surface and micropolar lubricant

2017 ◽  
Vol 69 (6) ◽  
pp. 844-862 ◽  
Author(s):  
Chandra B. Khatri ◽  
Satish C. Sharma
Keyword(s):  
Design Methodology ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Numerical Technique ◽  
Surface Texturing ◽  
Textured Surface ◽  
Performance Parameters ◽  
Content Type ◽  
Fluid Theory ◽  
Bearing System

Purpose The aim of the present paper is to study the combined influence of textured surface and micropolar lubricant behaviour on the performance of two-lobe hole-entry hybrid journal bearing system. The bearing performance parameters of the textured circular/two-lobe hole-entry hybrid journal bearing system have been computed against the constant vertical external load supported by the bearing. Design/methodology/approach In this work, Eringen’s micropolar fluid theory has been used to derive the governing Reynolds equation. The consequent solution of the governing Reynolds equation has been obtained by using finite element method (FEM) numerical technique. Findings The present study indicates that the use of the textured surface, two-lobe profile of bearing and micropolar lubricant, significantly enhances the bearing performance as compared to non-textured circular journal bearing. Originality/value The present study concerning the influence of surface texturing on the behaviour of the two-lobe hole-entry hybrid journal bearing lubricated with micropolar lubricant is original. The theoretically simulated results of the present study will be useful to design an efficient journal bearing system.

Multigrid method for the solution of EHL point contact with bio-based oil as lubricants for smooth and rough asperity

2018 ◽  
Vol 70 (4) ◽  
pp. 599-611 ◽  
Author(s):  
Vishwanath B. Awati ◽  
Shankar Naik ◽  
Mahesh Kumar N.
Keyword(s):  
Design Methodology ◽  
Reynolds Equation ◽  
Multigrid Method ◽  
Approximation Scheme ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Alternative Source ◽  
Content Type ◽  
Longitudinal Roughness ◽  
Isothermal Case

Purpose The purpose of this paper is to study the elastohydrodynamic lubrication point contact problem with bio-based oil as lubricants for an isothermal case. The simulation of the problem is analyzed on smooth and rough asperity. Design/methodology/approach The modified Reynolds equation is discretized using finite difference and multigrid method with full approximation scheme (FAS), applied for its solution with varying load and speed. Findings This paper traces out the comparison of minimum and central film thickness with the standard formulation of Hamrock and Dowson. The effect of longitudinal roughness on surfaces is investigated by means of numerical simulations. Originality/value The results obtained are comparable with the standard results, and are shown by graphs and tables. Bio-based products bring out an alternative source of lubricant to reduce energy crises.

Automated element grouping and self-stress identification of tensegrities

2015 ◽  
Vol 32 (6) ◽  
pp. 1643-1660 ◽  
Author(s):  
Kambiz Koohestani
Keyword(s):  
Design Methodology ◽  
Feasible Solution ◽  
State Of The Art ◽  
The Self ◽  
Content Type ◽  
Stress Mode ◽  
Novel Approach ◽  
Minimisation Problem ◽  
Feasible Solutions

Purpose – The determination of feasible self-stress modes and grouping of elements for tensegrities with predefined geometry and multiple self-stress modes is very important, though difficult, in the design of these structures. The purpose of this paper is to present a novel approach to the automated element grouping and self-stress identification of tensegrities. Design/methodology/approach – A set of feasible solutions conforming to the unilateral behaviour of elements is obtained through an optimisation process, which is solved using a genetic algorithm. Each chromosome in the population having a negative fitness is a distinctive feasible solution with its own grouping characteristic, which is automatically determined throughout the evolution process. Findings – The self-stress identification is formulated through an unconstrained minimisation problem. The objective function of this minimisation problem is defined in such a way that takes into account both the feasibility of a solution and grouping of elements. The method generates a set of feasible self-stress modes rather than a single one and automatically and simultaneously suggests a grouping of elements for every feasible self-stress mode. A self-stress mode with a minimal/subminimal grouping of elements is also obtained. Originality/value – The method can efficiently generate sets of feasible solutions rather than a single one. The authors also address one of the challenging issues related to this identification, i.e., automated grouping of elements. These features makes the method very efficient since most of the state-of-the-art methods address the self-stress identification of tensegrities based on predefined groupings of elements whilst providing only a single corresponding solution.

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