Theoretical Analysis of Capacitive Effect of Roller Bearings on Repeated Starts and Stops of a Machine Operating Under the Influence of Shaft Voltages

1992 ◽  
Vol 114 (4) ◽  
pp. 818-822 ◽  
Author(s):  
Har Prashad
Keyword(s):  
Theoretical Analysis ◽  
Film Thickness ◽  
Power Supply ◽  
Charge Accumulation ◽  
Roller Bearings ◽  
Capacitive Effect ◽  
Time Required

A theoretical analysis has been carried out to study the capacitive effects of roller bearings on repeated starts and stops of a machine operating under the influence of shaft voltages. The analysis gives the time required for the charge accumulation and increase of charge with time on the bearing surfaces based on bearing capacitance, resistance of film thickness and the shaft voltage. Also, it investigates the effect of gradual leakage of the accumulated charges with time as the shaft voltage falls as soon as the power supply to the machine is switched off. This paper gives an approach to determine ratio of the number of shaft revolutions required for charge accumulation and gradual discharge of the accumulated charges on the bearing surfaces depending on bearing to shaft voltage. Also, number of repeated starts and stops before initiation of craters on roller track of races are established to restrict the deterioration and damage of bearings.

Theoretische Analyse eines neuen Loslagerkonzepts*/Theoretical analysis of a new floating bearing - The simulated operational behavior of FRB bearings in comparison to reference bearings

2015 ◽  
Vol 105 (05) ◽  
pp. 285-290
Author(s):  
C. Brecher ◽  
M. Fey ◽  
J. Falker
Keyword(s):  
Experimental Investigation ◽  
Theoretical Analysis ◽  
High Speed ◽  
Contact Point ◽  
Ball Bearings ◽  
Roller Bearings ◽  
Cylindrical Roller ◽  
Bearing System

Das Floating-Roller-Ball (FRB)-Lager ist ein Konzept für Radiallager als Loslager für Hochgeschwindigkeits-Motorspindeln, das die Vorteile von Zylinderrollenlagern und angestellten Mehrpunktlagern in einer neuen Wälzkörpergeometrie kombiniert. Zur Auslegung des ersten Prototyps wurde mithilfe eines Berechnungstools das theoretische Betriebsverhalten untersucht. Die Berechnungsergebnisse liefern Randbedingungen als Grundlage zur experimentellen Untersuchung des Lagerkonzepts.   Floating roller ball bearings provide a new floating bearing system for high-speed motor spindles, combining the advantages of both cylindrical roller bearings and elastically mounted multi-contact point bearings in a new roller geometry. To design the first prototype, the operational behavior of the bearing system was analyzed theoretically by a new calculation tool. The results provide the basis for the experimental investigation of the bearing concept.

The Influence of Quantizing Magnetic Field on The Magnetic Susceptibilities in Ultra Thin Films of Dilute Magnetic Materials

1993 ◽  
Vol 313 ◽  
Author(s):  
Kamakhya P Ghatak ◽  
S. N. Biswas
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Thin Films ◽  
Theoretical Analysis ◽  
Film Thickness ◽  
Magnetic Materials ◽  
Ultrathin Films ◽  
Surface Concentration ◽  
Magnetic Susceptibilities ◽  
Quantizing Magnetic Field

ABSTRACTIn this paper we have studied the dia and paramagnetic susceptibilities of the holes in ultrathin films of dilute magnetic materials in the presence of a quantizing magnetic field and compared the same with that of the bulk specimens under magnetic quantization for the purpose of relative comparison. It is found, taking Hg1−xMnxTe and Cd1−xMnxSe as examples, that both the susceptibilities increase with decreasing film thickness and increasing surface concentration in oscillatory Manners. The numerical values of the susceptibilities in ultrathin films of dilute magnetic materials are greater than that of the bulk and the theoretical analysis is in agreement with the experimental data as reported elsewhere.

Report Paper 3: Elastohydrodynamic Lubrication of ‘O’ Ring Seals

1969 ◽  
Vol 184 (12) ◽  
pp. 197-200
Author(s):  
I. A. Gibson ◽  
C. J. Hooke ◽  
J. P. O'Donoghue
Keyword(s):  
Theoretical Analysis ◽  
Film Thickness ◽  
Pressure Gradient ◽  
Contact Zone ◽  
Elastohydrodynamic Lubrication ◽  
Iterative Solution ◽  
Contact Conditions ◽  
Dry Contact

This report gives details of a theoretical analysis of the lubrication of ‘O’ ring seals. Under dry contact conditions the pressure gradient at inlet to the contact zone is infinite, and an iterative solution has been developed to determine the inlet sweep of pressure under conditions of elastohydrodynamic lubrication. The exit film thickness and pressures have also been determined for conditions of variable outlet viscosity and pressure gradient. Typical results for an ‘O’ ring are given for a standard seal section.

Theoretical Analysis on Resistance-Temperature Characteristic of Ni/HCl-PANI Composites

2014 ◽  
Vol 852 ◽  
pp. 142-146 ◽  
Author(s):  
Sui Yu Qiu ◽  
Zhi Wei Yang ◽  
Hong Qiu
Keyword(s):  
Transition Temperature ◽  
Theoretical Analysis ◽  
Film Thickness ◽  
Temperature Characteristic ◽  
Substrate Thickness ◽  
Upper Limit ◽  
Metallic Conduction ◽  
Conduction Behavior ◽  
Doped Polyaniline ◽  
Semiconducting Behavior

Ni/HCl-PANI composites were formed by depositing Ni films on HCl-doped polyaniline (HCl-PANI) substrates. A simple parallel resistor model is used to analyze the resistance-temperature (R-T) characteristic of the composite within 30-300 K. The theoretical analysis reveals that the composite exhibits a metal-semiconductor transition within a certain thickness of the Ni film or the HCl-PANI substrate. The composite shows a semiconducting behavior at temperatures over the transition temperature and a metallic conduction behavior at temperatures below the transition temperature. The transition temperature increases with increasing Ni film thickness whereas it decreases with increasing HCl-PANI substrate thickness. When the Ni film thickness exceeds its upper limit or the HCl-PANI substrate thickness is below its lower limit, the composite only shows the metallic R-T characteristic. When the HCl-PANI substrate thickness exceeds its upper limit, the composite only exhibits the semicoducting R-T characteristic.

Oil Film Thickness in Lightly-Loaded Roller Bearings

1974 ◽  
Vol 16 (6) ◽  
pp. 386-390 ◽  
Author(s):  
H. Bahadoran ◽  
R. Gohar
Keyword(s):  
Film Thickness ◽  
Similar Condition ◽  
Thrust Bearing ◽  
Roller Bearing ◽  
Optical Interferometry ◽  
Oil Film ◽  
Roller Bearings ◽  
Tapered Roller

The effects of speed, load and roller geometry on the oil film thickness and shape in a complete roller bearing are demonstrated experimentally by means of optical interferometry. At quite moderate roller speeds, increase of film thickness becomes inhibited. This effect is attributed to a truncated inlet meniscus, a similar condition having been observed elsewhere with a ball-and-plate machine and with a model of a tapered-roller thrust bearing.

Computational analysis of the steady state performance of an adjustable/controllable multi-pad bearing profile under LBP orientations

2020 ◽  
pp. 095440622095770
Author(s):  
Girish Hariharan ◽  
Raghuvir Pai
Keyword(s):  
Steady State ◽  
Theoretical Model ◽  
Theoretical Analysis ◽  
Film Thickness ◽  
Computational Analysis ◽  
Fluid Film ◽  
Adjustable Mechanism ◽  
State Behaviour ◽  
Steady State Behaviour ◽  
Steady State Performance

A theoretical model of a four-pad bearing profile with unique adjustable or controllable features is simulated in the present study by considering load directed between the pads. Radial and tilt adjustable mechanism of the four bearing pads can effectively control and modify the rotor operating behaviour. Inward and outward motions of the bearing pads result in the generation of narrow and broader convergent regions, which directly influences the fluid film pressures. In the theoretical analysis, load-between-pad (LBP) orientations and pad adjustment configurations are taken account of by employing a modified film thickness equation. The effect of load position in influencing the steady state behaviour of the four-pad adjustable bearing under varied pad displaced conditions is analysed in this study. The outcome of the analysis highlighted the effectiveness of four-pad adjustable bearing in improving the steady state performance by operating under negative adjustment conditions and with load acting on the bearing pads.

Thermal Non-Newtonian EHL Analysis of Rib-Roller End Contact in Tapered Roller Bearings

1995 ◽  
Vol 117 (4) ◽  
pp. 646-654 ◽  
Author(s):  
Xiaofei Jiang ◽  
Pat Lam Wong ◽  
Zhiming Zhang
Keyword(s):  
Film Thickness ◽  
Surface Temperature ◽  
Thermal Effects ◽  
Friction Torque ◽  
Curvature Radius ◽  
Roller Bearings ◽  
Tapered Roller ◽  
Tapered Roller Bearings ◽  
Full Consideration ◽  
Newtonian Behavior

An EHL approach to the rib-roller end contact in tapered roller bearings has been achieved by taking into account the non-Newtonian behavior of lubricants and thermal effects and with full consideration of the peculiar geometrical and kinematic conditions. Two kinds of geometrical configurations of rib and roller end were investigated: tapered rib/spherical roller end and spherical rib/spherical roller end. Optimal ratios of curvature radius of roller end to rib face were deduced. The film thickness, friction torque, lubricant temperature, and surface temperature at various speeds and loads were calculated.

First Paper: Further Investigations of the Mechanics of Roller Bearings

1966 ◽  
Vol 181 (1) ◽  
pp. 339-348 ◽  
Author(s):  
P. Garnell
Keyword(s):  
Film Thickness ◽  
Electrical Resistance ◽  
Roller Bearing ◽  
Friction Torque ◽  
Roller Bearings ◽  
Torque Measurements

An earlier paper (1)† investigated roller and cage motion, friction torque, film thickness, and electrical resistance of a roller bearing. Further friction-torque measurements are presented and an analysis of friction losses in a roller bearing is made. Additional measurements of resistance are discussed.

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