scholarly journals Experimental Investigation of Clearance Influences on Cage Motion and Wear in Ball Bearings

2021 ◽  
Vol 11 (24) ◽  
pp. 11848
Author(s):  
Baogang Wen ◽  
Meiling Wang ◽  
Xu Zhang ◽  
Jingyu Zhai ◽  
Wei Sun
Keyword(s):  
Experimental Investigation ◽  
Vital Role ◽  
Operating Conditions ◽  
Ball Bearings ◽  
Test Rig ◽  
The Stability ◽  
The Relationship ◽  
Ring Frequency

Clearances of cages in ball bearings, including pocket and guiding clearances, play a vital role in the stability and reliability of bearings. In this paper, experiments on the cage motion and wear were carried out to investigate the influence of clearances in ball bearings. Firstly, the cages with a series of pocket and guiding clearances were specially designed and tested for prescribed operating conditions on a bearing test rig in which the cage motions were measured, and corresponding wear was also observed. Then, the normalized trajectory, waveform, and spectra of cage motion were constructed and compared to illustrate the effects of clearances on the cage motion and then to establish the relationship between cage motion and wear. Results reveal that the cage motion and wear are both significantly affected by its clearances. The increment of cage guiding clearance makes the whirl trajectories of the cage regular and the motion frequency of cage motion significantly change. However, the increment of cage pocket clearance make the whirl trajectories change from well-defined patterns to complicated ones, and the frequency of cage motion apparently changes. Additionally, the bearing wear is closely related to the cage motion. If the inner ring frequency is of domination for the cage motion, the cage guiding surface will wear seriously. While cage motion is dominated by two times cage frequency in spectrum domain, the cage pocket will wear more seriously.

Thermoacoustic Stability Analysis of a Kerosene-Fueled Lean Direct Injection Combustor Employing Acoustically and Optically Measured Transfer Matrices

2012 ◽  
Author(s):  
Bernhard C. Bobusch ◽  
Jonas P. Moeck ◽  
Christian Oliver Paschereit ◽  
Sermed Sadig
Keyword(s):  
Stability Analysis ◽  
Transfer Functions ◽  
Direct Injection ◽  
Network Models ◽  
Operating Conditions ◽  
Transfer Matrices ◽  
Test Rig ◽  
Lean Direct Injection ◽  
Calibration Measurement ◽  
The Stability

The assessment of the stability characteristics of kerosene-fueled, lean direct injection flames is an important issue for the design of low-emission aircraft engine combustion systems. To achieve this task, acoustic network models are widely used. In the present work, this technique is applied to determine the stability behavior of a liquid-fueled, lean direct injection combustor. The required transfer matrices have been measured in an atmospheric combustion test rig. The burner transfer matrix as well as the upstream and downstream reflection coefficients are obtained by using the multi-microphone method. Since the measurement of flame transfer functions for liquid-fueled flames is a complex task, two techniques are applied and compared. First, the flame response to loudspeaker forcing is measured with the multi-microphone technique. Second, a technique based on the simultaneous acquisition of different chemiluminescence signals is applied. The chemiluminescence response at four different wavelengths (310 nm, 407 nm, 431 nm, and 515 nm), corresponding to the species OH*, CH*, CO2* and C2*, respectively, are measured using photomultiplier tubes. With a calibration measurement at different operating conditions, it is possible to calculate the instantaneous heat release rate. Flame transfer functions and matrices are measured in the test rig with the two techniques. Additionally, all acoustically measured transfer matrices and optically measured transfer functions are used to predict possible unstable modes in the test rig. The experimental results and the stability analysis employing the measured flame transfer functions are in good agreement and demonstrate validity of the method.

Analysis and Experimental Investigation of the Stability of Intershaft Squeeze Film Dampers—Part 2: Control of Instability

1978 ◽  
Vol 100 (3) ◽  
pp. 558-562 ◽  
Author(s):  
D. H. Hibner ◽  
P. N. Bansal ◽  
D. F. Buono
Keyword(s):  
Experimental Investigation ◽  
Stability Analysis ◽  
Shear Deformation ◽  
System Stability ◽  
Squeeze Film ◽  
Viscous Damper ◽  
Test Rig ◽  
Squeeze Film Dampers ◽  
Stability Maps ◽  
The Stability

The results of an analytical and experimental investigation showing the existence of an intershaft viscous damper instability were presented in reference [1]. In the present investigation, a more comprehensive stability analysis is used to study the stability of the test rig which incorporates a modified intershaft bearing support. The analysis is applicable to large multi-mass, rotor-bearing systems and includes the effects of gyroscopic moments, shear deformation, bearing support flexibility, and damping. The results of the stability analysis are presented in the form of system stability maps which clearly indicate the effectiveness of the modification in improving the instability onset speed of the system. Also presented are the results of an experimental investigation which substantiate the analytical predictions.

An Experimental Investigation on the Temperature Distribution in Circular Journal Bearings

1986 ◽  
Vol 108 (4) ◽  
pp. 621-626 ◽  
Author(s):  
Junichi Mitsui ◽  
Yukio Hori ◽  
Masato Tanaka
Keyword(s):  
Experimental Investigation ◽  
Angular Position ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Test Rig ◽  
Clearance Ratio ◽  
Temperature Distributions ◽  
Wide Range ◽  
Lubricant Viscosity ◽  
Good Agreement

The temperature distributions in full circular bearings were measured in a test rig. The effects of journal speed, lubricant viscosity, and clearance ratio on the maximum bearing temperature and its location were discussed. The results were compared with the theoretical analysis by the present authors and good agreement was obtained over the wide range of operating conditions. The maximum bearing temperature is found to increase considerably with the increase of speed or lubricant viscosity and also with the decrease of clearance ratio. Its angular position is found to vary with speed and clearance ratio. These phenomena can be explained by the characteristics of maximum film temperature in the oil film.

scholarly journals Experimental investigation and thermal analysis of coupler-rocker ball bearing

2020 ◽  
Vol 24 (6 Part A) ◽  
pp. 3781-3793
Author(s):  
Abdullah Jamil ◽  
Bin Baharom ◽  
Alemu Lemma ◽  
Tadimalla Rao
Keyword(s):  
Mathematical Model ◽  
Thermal Analysis ◽  
Experimental Investigation ◽  
Steady State ◽  
Applied Load ◽  
Ball Bearing ◽  
Linear Trend ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Ball Bearings

Ball bearings are widely used in many machineries and industrial applications. Thermal behaviour of oscillating ball bearings is unknown due to its complex pendulum-like motion and is discussed in this research. In this research, the effect of operating conditions of the oscillating bearing performing coupler-rocker motion on the heat generation is experimentally investigated and verified using mathematical model. For this purpose, a coupler-rocker bearing testing rig was designed and fabricated and the test bearing is splash-lubricated in an oil sump. The loading of test bearing was done using two extension springs. The applied load on the bearing was varied from 0 to 750 N while the crank rpm was varied from 1200 rpm to 1800 rpm. Three lubricant grades were used namely, SAE30, SAE40, and SAE50. Experimental results showed that the temperature of coupler-rocker bearing approaches steady-state at about 12 minutes for all cases. The steady-state temperatures at variable conditions are observed to follow a linear trend.

Stability of Autokinetic Movement

1965 ◽  
Vol 21 (3) ◽  
pp. 715-718 ◽  
Author(s):  
Doris C. Gilbert ◽  
Judy P. Hahn ◽  
John H. Wackwitz ◽  
Robert M. Martin
Keyword(s):  
Experimental Investigation ◽  
Individual Differences ◽  
Apparent Movement ◽  
Individual Characteristic ◽  
One Dimension ◽  
Test Time ◽  
Personality Factors ◽  
Time Interval ◽  
The Stability ◽  
The Relationship

Experimental investigation into the relationship between the autokinetic illusion and personality factors requires greater knowledge of the generality of the various findings on individual differences. The stability of autokinetic movement was investigated by varying several conditions: instructional set (accuracy vs illusion), light source (stationary vs moving), sex of E, number and length of trials, re-test time interval. Results for female college Ss lend support to the hypothesis that one dimension of apparent movement, length of line, is a stable individual characteristic.

An Experimental Investigation on Thermal Conductivity and Viscosity of Graphene doped CNTs /TiO2 Nanofluid

2020 ◽  
Vol 17 (3) ◽  
Author(s):  
A.M. Zetty Akhtar ◽  
M.M. Rahman ◽  
K. Kadirgama ◽  
M.A. Maleque
Keyword(s):  
Thermal Conductivity ◽  
Zeta Potential ◽  
Base Fluid ◽  
Minimum Quantity Lubrication ◽  
Cutting Fluid ◽  
Cutting Zone ◽  
Observation Method ◽  
The Stability ◽  
The Relationship ◽  
Zeta Potential Analysis

This paper presents the findings of the stability, thermal conductivity and viscosity of CNTs (doped with 10 wt% graphene)- TiO2 hybrid nanofluids under various concentrations. While the usage of cutting fluid in machining operation is necessary for removing the heat generated at the cutting zone, the excessive use of it could lead to environmental and health issue to the operators. Therefore, the minimum quantity lubrication (MQL) to replace the conventional flooding was introduced. The MQL method minimises the usage of cutting fluid as a step to achieve a cleaner environment and sustainable machining. However, the low thermal conductivity of the base fluid in the MQL system caused the insufficient removal of heat generated in the cutting zone. Addition of nanoparticles to the base fluid was then introduced to enhance the performance of cutting fluids. The ethylene glycol used as the base fluid, titanium dioxide (TiO2) and carbon nanotubes (CNTs) nanoparticle mixed to produce nanofluids with concentrations of 0.02 to 0.1 wt.% with an interval of 0.02 wt%. The mixing ratio of TiO2: CNTs was 90:10 and ratio of SDBS (surfactant): CNTs was 10:1. The stability of nanofluid checked using observation method and zeta potential analysis. The thermal conductivity and viscosity of suspension were measured at a temperature range between 30˚C to 70˚C (with increment of 10˚C) to determine the relationship between concentration and temperature on nanofluid’s thermal physical properties. Based on the results obtained, zeta potential value for nanofluid range from -50 to -70 mV indicates a good stability of the suspension. Thermal conductivity of nanofluid increases as an increase of temperature and enhancement ratio is within the range of 1.51 to 4.53 compared to the base fluid. Meanwhile, the viscosity of nanofluid shows decrements with an increase of the temperature remarks significant advantage in pumping power. The developed nanofluid in this study found to be stable with enhanced thermal conductivity and decrease in viscosity, which at once make it possible to be use as nanolubricant in machining operation.

Coverage and Stability of NHx Terminated Cobalt and Ruthenium Surfaces: a First Principles Investigation

2019 ◽  
Author(s):  
Ji Liu ◽  
Michael Nolan
Keyword(s):  
Metal Surfaces ◽  
High Vacuum ◽  
Atomic Layer ◽  
Nitrogen Plasma ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Bridge Site ◽  
Stable Surface ◽  
Saturation Coverage ◽  
The Stability

<div>In the atomic layer deposition (ALD) of Cobalt (Co) and Ruthenium (Ru) metal using nitrogen plasma, the structure and composition of the post N-plasma NHx terminated (x = 1 or 2) metal surfaces are not well known but are important in the subsequent metal containing pulse. In this paper, we use the low-index (001) and (100) surfaces of Co and Ru as models of the metal polycrystalline thin films. The (001) surface with a hexagonal surface structure is the most stable surface and the (100) surface with a zigzag structure is the least stable surface but has high reactivity. We investigate the stability of NH and NH2 terminations on these surfaces to determine the saturation coverage of NHx on Co and Ru. NH is most stable in the hollow hcp site on (001) surface and the bridge site on the (100) surface, while NH2 prefers the bridge site on both (001) and (100) surfaces. The differential energy is calculated to find the saturation coverage of NH and NH2. We also present results on mixed NH/NH2-terminations. The results are analyzed by thermodynamics using Gibbs free energies (ΔG) to reveal temperature effects on the stability of NH and NH2 terminations. Ultra-high vacuum (UHV) and standard ALD</div><div>operating conditions are considered. Under typical ALD operating conditions we find that the most stable NHx terminated metal surfaces are 1 ML NH on Ru (001) surface (350K-550K), 5/9 ML NH on Co (001) surface (400K-650K) and a mixture of NH and NH2 on both Ru (100) and Co (100) surfaces.</div>

Examining the Kinships System of the Bodo

Think India ◽  
2019 ◽  
Vol 22 (3) ◽  
pp. 186-192
Author(s):  
Dr. Oinam Ranjit Singh ◽  
Dr. Nushar Bargayary
Keyword(s):  
Social Relationships ◽  
Social Cohesion ◽  
Social Relationship ◽  
Vital Role ◽  
Eastern Region ◽  
The North ◽  
Kinship System ◽  
North Eastern ◽  
The World ◽  
The Relationship

The Bodo of the North Eastern region of India have their own kinship system to maintain social relationship since ancient periods. Kinship is the expression of social relationship. Kinship may be defined as connection or relationships between persons based on marriage or blood. In each and every society of the world, social relationship is considered to be the more important than the biological bond. The relationship is not socially recognized, it fall outside the realm of kinship. Since kinship is considered as universal, it plays a vital role in the socialization of individuals and the maintenance of social cohesion of the group. Thus, kinship is considered to be the study of the sum total of these relations. The kinship of the Bodo is bilateral. The kin related through the father is known as Bahagi in Bodo whereas the kin to the mother is called Kurma. The nature of social relationships, the kinship terms, kinship behaviours and prescriptive and proscriptive rules are the important themes of the present study.

A pilot web former designed to study retention-formation relationships

2010 ◽  
Vol 25 (2) ◽  
pp. 185-194
Author(s):  
Anna Svedberg ◽  
Tom Lindström
Keyword(s):  
Pilot Scale ◽  
Operating Conditions ◽  
Montmorillonite Clay ◽  
Speed Ratio ◽  
Good Reproducibility ◽  
Total Solids ◽  
Retention Aids ◽  
Solids Content ◽  
Relationship Of ◽  
The Relationship

Abstract A pilot-scale fourdrinier former has been developed for the purpose of investigating the relationship between retention and paper formation (features, retention aids, dosage points, etc.). The main objective of this publication was to present the R-F (Retention and formation)-machine and demonstrate some of its fields of applications. For a fine paper stock (90% hardwood and 10% softwood) with addition of 25% filler (based on total solids content), the relationship between retention and formation was investigated for a microparticulate retention aid (cationic polyacrylamide together with anionic montmorillonite clay). The retention-formation relationship of the retention aid system was investigated after choosing standardized machine operating conditions (e.g. the jet-to-wire speed ratio). As expected, the formation was impaired when the retention was increased. Since good reproducibility was attained, the R-F (Retention and formation)-machine was found to be a useful tool for studying the relationship between retention and paper formation.

A FORECAST OF PRODUCTIVE LONGEVITY OF HOLSTEIN COWS BY INDIRECT SIGNS

2020 ◽  
Author(s):  
З.С. САНОВА
Keyword(s):  
Correlation Coefficient ◽  
Aging Process ◽  
Direct Relationship ◽  
Stability Index ◽  
Age At First Calving ◽  
Group I ◽  
Predicted Values ◽  
The Stability ◽  
Relationship Of ◽  
The Relationship

В статье представлены материалы о взаимосвязи продолжительности продуктивного использования коров с характеристикой устойчивости к деградации, с возрастом отела и удоем. В исследованной, разнородной по происхождению, группе животных для прогноза продуктивного периода коров, обусловленного устойчивостью к деградации и возрастом первого отела, пригодно уравнение регрессии, аргументами в котором являются индекс устойчивости, возраст первого отела в первой и второй степенях. Коэффициент корреляции межу предсказанными значениями продуктивного периода и его фактическими величинами в I группе составляет 0,502, во II - 0,604. При этом крайние варианты прогнозируются со статистическими ошибками 5 мес при оценке индекса устойчивости по 2 лактациям и 4,1 мес по 3, а средние варианты, соответственно, 1,6 и 1,51 мес. Индекс устойчивости к процессу старения является важной характеристикой биологических особенностей коров, определяющий их продуктивное долголетие. Его оценка по первым 2 и 3 лактациям имеет прямолинейную связь с продуктивным периодом (r=0,4109 и r=0,5270), соответственно. Зависимость продуктивного периода от возраста первого отела криволинейная — с увеличением возраста первого отела сокращается срок продуктивного использования, при возрасте первого отела более 1400 дней срок продуктивного использования колеблется от 1,33 до 1,41 лактации. Коэффициент корреляции между этими характеристиками коров составляет - 0,2164 в I и - 0,2620 во II группах. The article presents materials about the relationship of the duration of productive use of cows with the characteristic of resistance to degradation, with the age of calving and milk yield. In the studied group of animals, which is heterogeneous in origin, the regression equation is suitable for predicting the productive period of cows due to resistance to degradation and the age of the first calving, the arguments of which are the stability index, the age of the first calving in the first and second degrees. The correlation coefficient between the predicted values of the productive period and its actual values in group I is 0.502, in group II - 0.604. At the same time, the extreme variants are predicted with statistical errors of 5 months when evaluating the stability index for 2 lactations and 4.1 months for 3, and the average variants, respectively, are 1.6 and 1.51 months. The index of resistance to the aging process is an important characteristic of the biological characteristics of cows, which determines their productive longevity. Its estimate for the first 2 and 3 lactations has a direct relationship with the productive period (r=0.4109 and r=0.5270), respectively. The dependence of the productive period age at first calving curvilinear with increasing age at first calving reduces the time to productive use, while age at first calving of more than 1400 days, the period of productive use ranges from 1.33 to 1.41 lactation. The correlation coefficient between these characteristics of cows is-0.2164 in I and-0.2620 in II groups.

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