scholarly journals Electrical Discharges in Oil-Lubricated Rolling Contacts and Their Detection Using Electrostatic Sensing Technique

Sensors ◽  
2022 ◽  
Vol 22 (1) ◽  
pp. 392
Author(s):  
Kamran Esmaeili ◽  
Ling Wang ◽  
Terry J. Harvey ◽  
Neil M. White ◽  
Walter Holweger
Keyword(s):  
High Current Density ◽  
Rolling Contact ◽  
Voltage Measurement ◽  
Electrical Discharges ◽  
Steel Rolling ◽  
Bearing Life ◽  
Wide Range ◽  
Robust Techniques ◽  
Rolling Elements ◽  
Current Densities

The reliability of rolling element bearings has been substantially undermined by the presence of parasitic and stray currents. Electrical discharges can occur between the raceway and the rolling elements and it has been previously shown that these discharges at relatively high current density levels can result in fluting and corrugation damages. Recent publications have shown that for a bearing operating at specific mechanical conditions (load, temperature, speed, and slip), electrical discharges at low current densities (<1 mA/mm2) may substantially reduce bearing life due to the formation of white etching cracks (WECs) in bearing components, often in junction with lubricants. To date, limited studies have been conducted to understand the electrical discharges at relatively low current densities (<1 mA/mm2), partially due to the lack of robust techniques for in-situ quantification of discharges. This study, using voltage measurement and electrostatic sensors, investigates discharges in an oil-lubricated steel-steel rolling contact on a TE74 twin-roller machine under a wide range of electrical and mechanical conditions. The results show that the discharges events between the rollers are influenced by temperature, load, and speed due to changes in the lubricant film thickness and contact area, and the sensors are effective in detecting, characterizing and quantifying the discharges. Hence, these sensors can be effectively used to study the influence of discharges on WEC formation.

Polyaniline: Influence of Polymerization Current Density

1994 ◽  
Vol 369 ◽  
Author(s):  
Steen Skaarup ◽  
L.M.W.K. Gunaratne ◽  
Keld West ◽  
Birgit Zachau-Christiansen
Keyword(s):  
Cyclic Voltammetry ◽  
Current Density ◽  
High Current Density ◽  
Electrochemical Polymerization ◽  
Regular Structure ◽  
Spectral Lines ◽  
Complex Nature ◽  
Cyclic Voltammograms ◽  
Layer By Layer ◽  
Current Densities

AbstractPolyaniline has been synthesized in propylene carbonate by galvanostatic electrochemical polymerization at current densities between 16 and 1000 μA/cm2. Earlier results for polypyrrole have shown that low and high current density films have different properties: The films synthesized at low current density have a higher conjugation length and a more regular structure. The corresponding effect in PANI has been investigated by cyclic voltammetry and UV/visible spectroscopy. Simultaneous measurement of cyclic voltammograms and the absorbtion of selected spectral lines is used because of the complex nature of the PANI system which involves several redox systems as well as forms differing in the degree of protonation and morphology.The main result is that the method of galvanostatic synthesis at low current densities (-16 μA/cm2) produces polyaniline polymers of different, more conjugated and more regular structure than those prepared at higher current densities. The standard method of in situ layer-by-layer polymerization of conducting polymers during cyclic voltammetry often results in uncontrolled and unmeasured current densities of 0.5-2 mA/cm2 which produces a film that probably has a less regular structure containing more deviations from ideality.

scholarly journals Stabilizing electrodeposition in elastic solid electrolytes containing immobilized anions

2016 ◽  
Vol 2 (7) ◽  
pp. e1600320 ◽  
Author(s):  
Mukul D. Tikekar ◽  
Lynden A. Archer ◽  
Donald L. Koch
Keyword(s):  
Elastic Solid ◽  
Present Theory ◽  
Metal Electrode ◽  
Mitigation Strategies ◽  
Factors Affecting ◽  
Wide Range ◽  
Current Densities ◽  
Morphological Instabilities ◽  
The Stability

Ion transport–driven instabilities in electrodeposition of metals that lead to morphological instabilities and dendrites are receiving renewed attention because mitigation strategies are needed for improving rechargeability and safety of lithium batteries. The growth rate of these morphological instabilities can be slowed by immobilizing a fraction of anions within the electrolyte to reduce the electric field at the metal electrode. We analyze the role of elastic deformation of the solid electrolyte with immobilized anions and present theory combining the roles of separator elasticity and modified transport to evaluate the factors affecting the stability of planar deposition over a wide range of current densities. We find that stable electrodeposition can be easily achieved even at relatively high current densities in electrolytes/separators with moderate polymer-like mechanical moduli, provided a small fraction of anions are immobilized in the separator.

scholarly journals Analytical Method for Differential Amplifier Offset Voltage Analysis

1970 ◽  
Vol 108 (2) ◽  
pp. 51-54 ◽  
Author(s):  
A. Baskys ◽  
L. Nickelson ◽  
R. Navickas
Keyword(s):  
Current Density ◽  
Analytical Method ◽  
High Current Density ◽  
Differential Amplifier ◽  
Bipolar Junction Transistors ◽  
High Current ◽  
Voltage Measurement ◽  
Narrow Region ◽  
Offset Voltage ◽  
Transistor Model

The analytical method for differential amplifier offset voltage analysis is presented in the work. The method is developed for the amplifier based on the bipolar junction transistors that operate at high-current density. The transistor model based on the equation of the junction, which takes into account the dependence of majority carrier boundary concentrations on junction voltage that should be considered at high-current density, is used as the base for derivation of input offset voltage equations. The derived equations are valid in the narrow region of current, at which the differential amplifier input offset voltage measurement is provided. The obtained equations allow us to estimate the input offset voltage reduction ways. The results gained using suggested analytical analysis method are confirmed by the numerical investigation of the differential amplifier. Ill. 3, bibl. 11 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.108.2.144

Rolling Element Bearing Non-Linearity Effects

2000 ◽  
Author(s):  
N. S. Feng ◽  
E. J. Hahn
Keyword(s):  
Equations Of Motion ◽  
Rolling Element Bearing ◽  
Radial Clearance ◽  
Rotor Systems ◽  
Bearing Life ◽  
Rolling Element ◽  
Bearing Load ◽  
Rolling Elements ◽  
Element Bearing ◽  
Negative Clearance

Non-linearity effects in rolling element bearings arise from two sources, viz. the Hertzian force deformation relationship and the presence of clearance between the rolling elements and the bearing races. Assuming that centrifugal effects may be neglected and that the presence of axial preload is appropriately reflected in a corresponding change in the radial clearance, this paper analyses a simple test rig to illustrate that non-linear phenomena such as synchronous multistable and nonsynchronous motions are possible in simple rigid and flexible rotor systems subjected to unbalance excitation. The equations of motion of the rotor bearing system were solved by transient analysis using fourth order Runge Kutta. Of particular interest is the effect of clearance, governed in practice by bearing specification and the amount of preload, on the vibration behaviour of rotors supported by ball bearings and on the bearing load. It is shown that in the presence of positive clearance, there exists an unbalance excitation range during which the bearing is momentarily not transmitting force owing to contact loss, resulting in rolling element raceway impact with potentially relatively high bearing forces; and indicating that for long bearing life, operation with positive clearance should be avoided in the presence of such unbalance loading. Once the unbalance excitation is high enough to avoid such contact loss, it is the bearings with zero or negative clearance which produce maximum bearing forces.

Mechanical effect of an electric field on nanostructure elements

2021 ◽  
Vol 3 ◽  
pp. 79-82
Author(s):  
V. P. Babaev ◽  
◽  
S. V. Zaitsev ◽  
K. A. Inshakova ◽  
A. N. Shaykin ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Potential ◽  
High Intensity ◽  
Structural Damage ◽  
High Surface ◽  
Mechanical Effect ◽  
Surface Curvature ◽  
Electrical Discharges ◽  
Experimental Estimation ◽  
Wide Range

A computational and experimental estimation of the magnitude of forces acting in a high-intensity electric field on elements of nanoconstructions with a high surface curvature is made. Depending on the magnitude of the electric potential and vacuum conditions, these forces can vary both in magnitude and direction over a wide range. They can cause structural damage, as well as provoke unwanted electrical discharges. The possibilities of useful application of these effects are analyzed.

Electromigration Phenomena in Sintered Nanoparticle Ag Systems Under High Current Density

2015 ◽  
Vol 2015 (HiTEN) ◽  
pp. 000059-000063
Author(s):  
Ali Mansourian ◽  
Seyed Amir Paknejad ◽  
Qiannan Wen ◽  
Khalid Khtatba ◽  
Anatoly Zayats ◽  
...  
Keyword(s):  
High Current Density ◽  
Composition Studies ◽  
Void Formation ◽  
Sintering Process ◽  
Number Density ◽  
Momentum Exchange ◽  
Conduction Electrons ◽  
Fine Grained ◽  
Aspect Ratios ◽  
Current Densities

Electromigration (EM) refers to the movement of atoms inside a conductor due to momentum exchange with the conduction electrons. In this work the EM effect in samples of porous Ag fabricated from nanoparticles of Ag in a pressure free sintering process is studied. Current densities of 2.5×104 − 1.7×105 A/cm2 were applied to the samples for periods ranging up to 500 h. In a typical EM setup with a non-porous conductor, void formation occurs at the cathode and hillock formation at the anode. In this study, voids were not directly observed, but cracks were formed after prolonged electromigration, presumably as a result of void accumulation and coalescence. When the samples were placed in 150 °C ambient no hillocks were observed, but at room temperature nanorods were formed with sizes ranging up to 20 μm in length, typically 25 nm in diameter and with aspect ratios ranging from 20 to 1000. It was found that interrupting and restarting the current resulted in growth of new nanorods rather than growth of existing ones, and that growth was limited by welding of individual nanorods when a critical number density was reached. While similar nanorods have been formed from Ag thin films using thermal stress , the location of nanorods was unusual in that while the number density was highest at the anode, significant numbers also appeared at central and cathode locations. Another unusual feature of the observed EM was that the initial porous structure became refined with coarse pores and grains transforming into a fine grained and fine pored structure with elongated and locally orientated pores and grains. Elemental composition studies provide tentative understanding of the nanorod number density, size distribution and growth mechanism. In the geometry utilized for this study, temperature gradients are known to strongly influence the divergence of the EM induced atomic flux and hence resistivity measurements and COMSOL Finite Element modelling was used to determine the temperature in the sample taking into account joule heating, convection and conduction processes.

Theoretical Study on the Influence of Planet Gear Rim Thickness and Bearing Clearance on Calculated Bearing Life

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Andreas Fingerle ◽  
Jonas Hochrein ◽  
Michael Otto ◽  
Karsten Stahl
Keyword(s):  
High Efficiency ◽  
Roller Bearing ◽  
The Body ◽  
Fem Model ◽  
Bearing Life ◽  
Bearing Load ◽  
Rolling Elements ◽  
Planet Gear ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

Abstract Planetary gearboxes are becoming more popular due to their high-power density and potentially high efficiency. When the planet bearings are internally mounted, the body of the planet gear has to be hollow. The demand for large outer diameters due to high-load requirements might result in a small planet rim thickness. Depending on the rim thickness, its rigidity may become very low. Due to the low stiffness and the special load conditions caused by the double meshing, the deformation of the planet and its bearings are unique. In this paper, the influence of rim thickness on bearing load and lifetime is examined. The analysis is performed with a finite element method (FEM) model of a planet rim with a built-in cylindrical roller bearing. With the resulting planet deformation from the FEM calculation, the load distribution on the rolling elements in the bearing and the bearing lifetime according to ISO/TS 16281:2008 has been evaluated.

Theoretical Study on the Influence of Planet Gear Rim Thickness and Bearing Clearance on Calculated Bearing Life

2019 ◽  
Author(s):  
Andreas Fingerle ◽  
Jonas Hochrein ◽  
Michael Otto ◽  
Karsten Stahl
Keyword(s):  
High Efficiency ◽  
Roller Bearing ◽  
The Body ◽  
Fem Model ◽  
Bearing Life ◽  
Bearing Load ◽  
Rolling Elements ◽  
Planet Gear ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

Abstract Planetary gearboxes are becoming more popular due to their high power density and potentially high efficiency. When the planet bearings are internally mounted, the body of the planet gear has to be hollow. The demand for large outer diameters due to high load requirements might result in a small planet rim thickness. Depending on the rim thickness, its rigidity may become very low. Due to the low stiffness and the special load conditions caused by the double meshing, the deformation of the planet and its bearings are unique. In this paper, the influence of rim thickness on bearing load and lifetime are examined. The analysis is performed with an FEM model of a planet rim with a built-in cylindrical roller bearing. With the resulting planet deformation from the FEM calculation, the load distribution on the rolling elements in the bearing and the bearing lifetime according to ISO/TS 16281:2008 have been evaluated.

Sign in / Sign up

Export Citation Format

Share Document