Theoretical Analysis of the Effects of Instantaneous Charge Leakage on Roller Tracks of Roller Bearings Lubricated With High Resistivity Lubricants Under the Influence of Electric Current

1990 ◽  
Vol 112 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Har Prashad
Keyword(s):  
Electric Current ◽  
Contact Zone ◽  
Temperature Rise ◽  
Roller Bearing ◽  
Rolling Friction ◽  
Contact Stresses ◽  
High Resistivity ◽  
Roller Bearings ◽  
Instantaneous Temperature ◽  
Number Of Cycles

An analysis is presented for determining the effects of instantaneous charge leakage on the rise of contact temperature between rollers and roller track of races of roller bearings lubricated with high resistivity lubricant. Analysis is also given for the contact stresses on the races which lead to initiation of craters by the arcing effect on the roller tracks and subsequent damage to the roller bearing. Estimates of the leakage of charge between roller tracks and rollers during momentary asperity contacts along with an expression for the instantaneous contact resistance between roller and race was used to establish heat generated and instantaneous temperature rise in the contact zone on the roller tracks in each shaft revolution. Using this temperature rise, the contact stresses were determined and the minimum number of cycles was calculated before craters are initiated on the roller track of the races. The number of cycles thus determined corresponds, within the reasonable limits, to the appearance of the craters on the roller track of the inner race of a roller bearing, operated under the influence of electric current. Subsequently, the ratio of reduction in bearing life with that of the bearing operated under rolling friction without the influence of electric current is established. This paper gives general guidance for determination of instantaneous temperature rise due to charge leakage in the contact zone and makes it possible to predict the life of a roller bearing lubricated with high resistivity lubricant under the influence of electric current before the craters appear on the roller tracks.

An Experimental Investigation of Cylindrical Roller Bearings Having Annular Rollers

1976 ◽  
Vol 98 (4) ◽  
pp. 538-543 ◽  
Author(s):  
A. Suzuki ◽  
A. Seireg
Keyword(s):  
Experimental Investigation ◽  
Temperature Rise ◽  
Load Distribution ◽  
Static Load ◽  
Numerical Solutions ◽  
Roller Bearing ◽  
Roller Bearings ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

This study deals with an experimental investigation of a cylindrical roller bearing having annular rollers. Comparisons are made with a solid roller bearing having the same configuration and dimensions. Radial deformations and load distribution between rollers are measured under static load and compared with numerical solutions. Bearing temperature rise and roller wear are investigated in a specially designed tester. A radioactive tracing technique is utilized for the measurement of roller wear and proved to be reliable for wear detection. The results show several advantages of annular rollers over the solid rollers.

Electric Current Pulse Welding of Titanium with 18-10 Stainless Steel

2009 ◽  
Vol 83-86 ◽  
pp. 1251-1253 ◽  
Author(s):  
E.G. Grigoryev ◽  
V.N. Bazanov
Keyword(s):  
Stainless Steel ◽  
Electric Current ◽  
Current Pulse ◽  
Contact Zone ◽  
Welded Joints ◽  
High Speed ◽  
Welded Joint ◽  
Electric Current Pulse ◽  
Pulse Effect ◽  
Different Thickness

The purpose of the work was to determine the capabilities of the pulse effect of electric current and pressure to produce welded joints of various component parts of different thickness from 18-10 stainless steel and titanium. Application of electric current pulses on the surfaces of contacting metallic conductors leads to considerable changes in the surface structure. Depending on the initial state of the surfaces and parameters of the pulse effect this can result in melting without formation of joints, formation of a strong welded joint with characteristics no worse than those of welded metals, and in destruction of the contact zone. A combination of a short electric pulse with simultaneous application of mechanical pressure in the weld zone causes high-speed deformation of the contact zone. The process of joint formation itself does not cause any appreciable diffusion during welding. The greatest energy emission and the maximal heating occur on the contacting surfaces being welded with the passage of an electric current pulse through the welding zone. Simultaneously with intensive heating, and due to applied pressure, high-speed deformation of materials takes place and a strong welded joint is formed. Optimal parameters for the welding of titanium and 18-10 stainless steel have been determined on the basis of the tests conducted. Investigations into the welding of titanium and 18-10 stainless steel have shown that application of a short electric current pulse and pressure produces stronger welded joints composed of both similar and different metals of considerably different thickness.

Threshold Stress Criterion in New Wheel/Rail Interaction for Limiting Rail Damage Under Heavy Axle Loads

1992 ◽  
Vol 114 (3) ◽  
pp. 284-288 ◽  
Author(s):  
S. Kumar ◽  
S. P. Singh
Keyword(s):  
Threshold Stress ◽  
Rolling Friction ◽  
Contact Stresses ◽  
Rolling Contact ◽  
Internal Damage ◽  
Stress Criterion ◽  
Plasticity Region ◽  
Proper Design ◽  
Axle Loads ◽  
Qualitative Discussion

This paper presents a qualitative discussion of the effects of increasing new (initial) wheel-rail contact stresses on the degree of damage to the rail due to heavy axle loads. The importance and need of heavy axle loads and its relationship to rail damage as a result of the increasing wheel-rail contact stresses is discussed. Various mechanisms of energy absorption/losses due to free rolling and modes of rail damage are presented. These modes include surface and internal damage due to wear, contact shear, plasticity, fatigue, shelling, crack formation, etc. The concept of threshold stress observed in free rolling friction much earlier by Drutowski is discussed and analyzed. It is believed by the authors that the threshold stress is s material property. This concept of threshold stress, based on sharply increased rates of wear in free rolling contact, is then presented and analyzed. Considerations of increased plasticity-region development, due to increasing contact stresses and their relationship to increased rates of wear seen in experiments, is utilized to determine an upper bound of contact stresses for new wheel and rail under heavy axle load conditions. It is indicated that new wheel-rail profiles, which will achieve contact stresses below the threshold stress, will enable the U.S. railroads to carry heavy axle loads without serious future damage to the rails. It is concluded that a satisfactory solution for maintaining rail integrity under heavy axle loads is possible with proper design accompanied with laboratory experimentation for the new steels as they may be used in the rails.

scholarly journals Improvement of Roller Bearing Diagnosis with Unlabeled Data Using Cut Edge Weight Confidence Based Tritraining

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Wei-Li Qin ◽  
Wen-Jin Zhang ◽  
Zhen-Ya Wang
Keyword(s):  
Fault Diagnosis ◽  
Roller Bearing ◽  
Unlabeled Data ◽  
Edge Weight ◽  
Ring Fault ◽  
Bearing Fault ◽  
Cut Edge ◽  
Bearing Fault Diagnosis ◽  
Roller Bearings ◽  
Diagnosis Method

Roller bearings are one of the most commonly used components in rotational machines. The fault diagnosis of roller bearings thus plays an important role in ensuring the safe functioning of the mechanical systems. However, in most cases of bearing fault diagnosis, there are limited number of labeled data to achieve a proper fault diagnosis. Therefore, exploiting unlabeled data plus few labeled data, this paper proposed a roller bearing fault diagnosis method based on tritraining to improve roller bearing diagnosis performance. To overcome the noise brought by wrong labeling into the classifiers training process, the cut edge weight confidence is introduced into the diagnosis framework. Besides a small trick called suspect principle is adopted to avoid overfitting problem. The proposed method is validated in two independent roller bearing fault experiment vibrational signals that both include three types of faults: inner-ring fault, outer-ring fault, and rolling element fault. The results demonstrate the desirable diagnostic performance improvement by the proposed method in the extreme situation where there is only limited number of labeled data.

The Effects of Current Leakage on Electroadhesion Forces in Rolling Friction and Magnetic Flux Density Distribution on the Surface of Rolling Element Bearings

1988 ◽  
Vol 110 (3) ◽  
pp. 448-455 ◽  
Author(s):  
Har Prashad
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Rolling Friction ◽  
High Resistivity ◽  
Magnetic Flux Density ◽  
Rolling Element Bearings ◽  
Electrical Fields ◽  
Low Resistivity ◽  
Pure Rolling ◽  
Rolling Element

The present work deals with the investigations carried out on the various rolling element bearings after being operated under the influence of electric fields, and pure rolling friction on the roller bearing test machine. The significant magnetic flux density was detected on surfaces of the bearings lubricated with low-resistivity grease under the influence of electrical fields. No such phenomenon was observed either on bearings using high or low-resistivity greases under pure rolling friction or on bearings lubricated with high-resistivity grease under the influence of electrical fields. New bearing surfaces do not show significant magnetic flux density but it has been detected after long operation on different motor bearings, lubricated with low resistivity greases. The electroadhesion forces in the bearings using low-resistivity greases increase under the influence of electrical fields in contrast to those with high resistivity greases. Under pure rolling friction resistivity of greases do not affect the electroadhesion forces. The investigations reported in this paper along with the study of damaged/corrugated surfaces, and deterioration of the used greases [1, 2, 3], the leakage of current leading to failure of the noninsulated motor bearings can be established.

Transient plasto-elastohydrodynamic lubrication concerning surface features with application to split roller bearings

2020 ◽  
pp. 135065012092756
Author(s):  
Tobias Hultqvist ◽  
Aleks Vrček ◽  
Tomas Johannesson ◽  
Pär Marklund ◽  
Roland Larsson
Keyword(s):  
Internal Combustion Engines ◽  
Roller Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Combustion Engines ◽  
Transient Effects ◽  
Finite Element Software ◽  
Accumulated Damage ◽  
Roller Bearings ◽  
Novel Approach ◽  
Modelling Approach

The use of roller bearings as crankshaft main bearings has shown potential in reducing the fuel consumption of internal combustion engines. An effective way to mount the roller bearing onto the crankshaft is to split the outer ring. However, this may lead to a severe out-of-roundness in the split region when the bearing is mounted, further implying increased noise, vibrations and contact stresses. In this work, a novel approach to study the plasto-elastohydrodynamic contact using commercial finite element software is developed. The modelling approach is based on the contact moving in space, allowing for the stress history based on the lubricant pressure to be studied in a straight-forward manner. The model is first utilised to study the influence of asperities on the lubricating conditions, indicating that stresses may exceed the yield strength of the material due to the transient effects taking place when the surface feature is over-rolled. Thereafter, the model is used to analyse the step in a mounted crankshaft roller bearing with the purpose of specifying a critical step height, which implies zero plasticity and thereby a reduced risk of accumulated damage in the vicinity of the step.

scholarly journals Roller Bearing Fault Diagnosis Based on Adaptive Sparsest Narrow-Band Decomposition and MMC-FCH

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Yanfeng Peng ◽  
Junhang Chen ◽  
Yanfei Liu ◽  
Junsheng Cheng ◽  
Yu Yang ◽  
...  
Keyword(s):  
Fault Diagnosis ◽  
Narrow Band ◽  
Matching Pursuit ◽  
Roller Bearing ◽  
Bearing Fault Diagnosis ◽  
Roller Bearings ◽  
Performance Accuracy ◽  
Mode Decomposition ◽  
Fault Features ◽  
Margin Classification

Adaptive sparsest narrow-band decomposition (ASNBD) method is proposed based on matching pursuit (MP) and empirical mode decomposition (EMD). ASNBD obtains the local narrow-band (LNB) components during the optimization process. Firstly, an optimal filter is designed. The parameter vector in the filter is obtained during optimization. The optimized objective function is a regulated singular local linear operator so that each obtained component is limited to be a LNB signal. Afterward, a component is generated by filtering the original signal with the optimized filter. Compared with MP, ASNBD is superior in both the physical meaning and the adaptivity. Drawbacks in EMD such as end effect and mode mixing are reduced in the proposed method because the application of interpolation function is not required. To achieve the fault diagnosis of roller bearings, raw signals are decomposed by ASNBD at first. Then, appropriate features of the decomposed results are chosen by applying distance evaluation technique (DET). Afterward, different faults are recognized by utilizing maximum margin classification based on flexible convex hulls (MMC-FCH). Comparisons between EMD and ASNBD show that the proposed method performs better in the antinoise performance, accuracy, orthogonality, and extracting the fault features of roller bearings.

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.

On the Detectability of Roller Bearing Damage by Frequency Analysis

1993 ◽  
Vol 207 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Y-T Su ◽  
Y-T Sheen
Keyword(s):  
Frequency Analysis ◽  
Roller Bearing ◽  
Vibration Spectra ◽  
Frequency Information ◽  
Roller Bearings ◽  
Bearing Damage

This study investigates the detectability of roller bearing damage by the frequency analysis of bearing vibrations. The magnitude characteristics of peaks in the vibration spectra are analysed. It is shown that the frequency information of vibration spectra for undamaged roller bearings can be the same as that for damaged ones. However, the magnitude information of vibration spectra for undamaged roller bearings is different from that for damaged ones. Thus, to detect the initial fault of roller bearing reliably, both the frequency information and magnitude information of vibration spectra have to be used.

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