scholarly journals Predicting Steady State Temperature, Life, Skid and Film Thickness in a Greased Preloaded Hybrid Ball Bearing

1995 ◽  
Author(s):  
Joseph V. Poplawski ◽  
David R. Atwell ◽  
Michael J. Lubas ◽  
Vladimir Odessky
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Ball Bearing ◽  
Thrust Bearing ◽  
Outer Race ◽  
Steady State Temperature ◽  
Parametric Studies ◽  
Ball Diameter ◽  
Hybrid Bearing ◽  
Stress Fatigue

This paper describes the use of the SHABERTH computer program supplemented with experimental temperature and skid data to quantify steady state bearing operation. Parametric studies on ball diameter and number, contact angle, curvature, grease type and preload are presented with their influence on contact stress, fatigue life, skid load, film thickness and inner and outer race temperatures. These results are compared for a steel vs. hybrid bearing set in a DB and DFSL mounting. The method presented can be applied to the design of other steel and hybrid ball thrust bearing systems.

Predicting Steady-State Temperature, Life, Skid, and Film Thickness in a Greased Preloaded Hybrid Ball Bearing

1996 ◽  
Vol 118 (2) ◽  
pp. 443-448 ◽  
Author(s):  
J. V. Poplawski ◽  
D. R. Atwell ◽  
M. J. Lubas ◽  
V. Odessky
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Ball Bearing ◽  
Thrust Bearing ◽  
Outer Race ◽  
Steady State Temperature ◽  
Parametric Studies ◽  
Ball Diameter ◽  
Hybrid Bearing ◽  
Stress Fatigue

This paper describes the use of the SHABERTH computer program supplemented with experimental temperature and skid data to quantify steady-state bearing operation. Parametric studies on ball diameter and number, contact angle, curvature, grease type, and preload are presented with their influence on contact stress, fatigue life, skid load, film thickness, and inner and outer race temperatures. These results are compared for a steel versus hybrid bearing set in a DB and DFSL mounting. The method presented can be applied to the design of other steel and hybrid ball thrust bearing systems.

Steady State Performance Characteristics of a Tilting Pad Thrust Bearing

2000 ◽  
Vol 123 (3) ◽  
pp. 608-615 ◽  
Author(s):  
Sergei B. Glavatskikh
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Thrust Bearing ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Shaft Speed ◽  
Oil Film ◽  
Tilting Pad ◽  
Bearing Load ◽  
Steady State Performance

The paper reports results of the experimental investigation into the steady state performance characteristics of a tilting pad thrust bearing typical of design in general use. Simultaneous measurements are taken of the pad and collar temperatures, the pressure distributions, oil film thickness, and power loss as a function of shaft speed, bearing load, and supplied oil temperature. The effect of operating conditions on bearing performance is discussed. A small radial temperature variation is observed in the collar. A reduction in minimum oil film thickness with load is approximately proportional to p−0.6, where p is an average bearing pressure. It has also been found that the oil film pressure profiles change not only due to the average bearing load but also with an increase in shaft speed and temperature of the supplied oil.

On Transient EHL of a Skew Roller Subjected to a Load Impact in Rolling Bearings

2017 ◽  
Vol 739 ◽  
pp. 108-119
Author(s):  
Xiao Ling Liu ◽  
Da Tong Song ◽  
Pei Ran Yang
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Transient Condition ◽  
Skew Angle ◽  
Transient Effect ◽  
Outer Race ◽  
Minimum Film Thickness ◽  
Finite Line ◽  
Load Impact

Based on the non-steady state operating condition in machine elements, numerical analysis of a transient elastohydrodynamic lubrication (EHL) finite line contact between a skewed roller and an outer race in cylindrical roller bearings was carried out, and a complete numerical solution of skewed roller pairs EHL under the transient condition was obtained. The effects of the load impact, together with the skewing angle impulses on the lubricating performance of skew roller pairs were discussed. Results show that, different from the steady state, the transient effect of the skew roller lubrication is mainly governed by the skew angle impulse, and the load impact. The film dimple is generated during the load impact, or the skewing angle impulse due to the normal approach velocity of the film. Compared to that of the ideal roller, the minimum film thickness decreases due to the roller skew when the transient load happens. Variation in the skewing angle leads to contrary distribution of the film thickness at the two half parts of the roller. Meanwhile, it can decrease the minimum film thickness and be harmful to the lubrication compared to the steady state. Consequently, the transient effect in the process of lubrication of skew roller pairs should not be neglected.

Steady-State Hydrodynamic Lubrication Modeled With the Payvar-Salant Mass Conservation Model

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Shangwu Xiong ◽  
Q. Jane Wang
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Thrust Bearing ◽  
Mass Conservation ◽  
Harmonic Mean ◽  
Small Scale ◽  
Finite Difference Schemes ◽  
Direct Solver ◽  
Computation Efficiency ◽  
Conservation Model

Steady-state smooth surface hydrodynamic lubrications of a pocketed pad bearing, an angularly grooved thrust bearing, and a plain journal bearing are simulated with the mass-conservation model proposed by Payvar and Salant. Three different finite difference schemes, i.e., the harmonic mean scheme, arithmetic mean scheme, and middle point scheme, of the interfacial diffusion coefficients for the Poiseuille terms are investigated by using a uniform and nonuniform set of meshes. The research suggests that for the problems with continuous film thickness and pressure distributions, the results obtained with these numerical schemes generally well agree with those found in the literatures. However, if the film thickness is discontinuous while the pressure is continuous, there may be an obvious deviation. Compared with both the analytical solution and other two schemes, the harmonic mean scheme may overestimate or underestimate the pressure. In order to overcome this problem artificial nodes should be inserted along the wall of the bearings where discontinuous film thickness appears. Moreover, the computation efficiency of the three solvers, i.e., the direct solver, the line-by-line the tridiagonal matrix algorithm (TDMA) solver, and the global successive over-relaxation (SOR) solver, are investigated. The results indicate that the direct solver has the best computational efficiency for a small-scale lubrication problem (around 40 thousand nodes). TDMA solver is more robust and requires the least storage, but the SOR solver may work faster than TDMA solver for thrust bearing lubrication problems. Numerical simulations of a group of grooved thrust bearings were conducted for the cases of different outer and inner radii, groove depth and width, velocity, viscosity, and reference film thickness. A curve fitting formula has been obtained from the numerical results to express the correlation of load, maximum pressure, and friction of an angularly grooved thrust bearing in lubrication.

scholarly journals Design and Evaluation of a 3 Million DN Series-Hybrid Thrust Bearing

1976 ◽  
Vol 98 (4) ◽  
pp. 586-594
Author(s):  
H. W. Scibbe ◽  
L. W. Winn ◽  
M. Eusepi
Keyword(s):  
Ball Bearing ◽  
Thrust Bearing ◽  
Supply System ◽  
Fluid Film ◽  
Shaft Speed ◽  
Speed Reduction ◽  
Oil Supply ◽  
Tenfold Increase ◽  
Hybrid Bearing ◽  
Bearing System

The design and experimental evaluation of a series-hybrid thrust bearing, consisting of a 150-mm ball bearing and a centrifugally actuated, conical, fluid-film bearing, is presented. Tests were conducted up to 16 000 rpm and at this speed an axial load of 15 600 N (3500 lb) was safely supported by the hybrid bearing system. Through the series-hybrid bearing principle, the effective ball bearing speed was reduced to approximately one-half of the shaft speed. A speed reduction of this magnitude would result in a tenfold increase in the ball bearing fatigue life. A successful evaluation of fluid-film bearing lubricant supply failure was performed repeatedly at an operating speed of 10 000 rpm. A complete and smooth changeover to full-scale ball bearing operation was effected when the oil supply to the fluid-film bearing was cut off. Reactivation of the fluid-film oil supply system produced a flawless return to the original mode of hybrid operation.

scholarly journals Identification of DC Thermal Steady-State Differential Inductance of Ferrite Power Inductors

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3854
Author(s):  
Salvatore Musumeci ◽  
Luigi Solimene ◽  
Carlo Stefano Ragusa
Keyword(s):  
Steady State ◽  
Input Voltage ◽  
Switching Frequency ◽  
Ohmic Losses ◽  
Steady State Temperature ◽  
Wide Range ◽  
Average Current ◽  
Power Inductors ◽  
Saturable Inductor ◽  
Thermal Steady State

In this paper, we propose a method for the identification of the differential inductance of saturable ferrite inductors adopted in DC–DC converters, considering the influence of the operating temperature. The inductor temperature rise is caused mainly by its losses, neglecting the heating contribution by the other components forming the converter layout. When the ohmic losses caused by the average current represent the principal portion of the inductor power losses, the steady-state temperature of the component can be related to the average current value. Under this assumption, usual for saturable inductors in DC–DC converters, the presented experimental setup and characterization method allow identifying a DC thermal steady-state differential inductance profile of a ferrite inductor. The curve is obtained from experimental measurements of the inductor voltage and current waveforms, at different average current values, that lead the component to operate from the linear region of the magnetization curve up to the saturation. The obtained inductance profile can be adopted to simulate the current waveform of a saturable inductor in a DC–DC converter, providing accurate results under a wide range of switching frequency, input voltage, duty cycle, and output current values.

Effect of Forced Convection on the Skin Thermal Expression of Breast Cancer

2004 ◽  
Vol 126 (2) ◽  
pp. 204-211 ◽  
Author(s):  
Lu Hu ◽  
Ashish Gupta ◽  
Jay P. Gore ◽  
Lisa X. Xu
Keyword(s):  
Forced Convection ◽  
Conjugate Heat Transfer ◽  
Transfer Problem ◽  
Skin Surface ◽  
Bioheat Transfer ◽  
Image Subtraction ◽  
Steady State Temperature ◽  
Parametric Studies ◽  
Airflow Field ◽  
Thermal Signature

A bioheat-transfer-based numerical model was utilized to study the energy balance in healthy and malignant breasts subjected to forced convection in a wind tunnel. Steady-state temperature distributions on the skin surface of the breasts were obtained by numerically solving the conjugate heat transfer problem. Parametric studies on the influences of the airflow on the skin thermal expression of tumors were performed. It was found that the presence of tumor may not be clearly shown due to the irregularities of the skin temperature distribution induced by the airflow field. Nevertheless, image subtraction techniques could be employed to eliminate the effects of the flow field and thermal noise and significantly improve the thermal signature of the tumor on the skin surface. Inclusion of the possible skin vascular response to cold stress caused by the airflow further enhances the signal, especially for deeply embedded tumors that otherwise may not be detectable.

scholarly journals Optical Analysis of Ball Bearing Starvation

1971 ◽  
Vol 93 (3) ◽  
pp. 349-361 ◽  
Author(s):  
L. D. Wedeven ◽  
D. Evans ◽  
A. Cameron
Keyword(s):  
Film Thickness ◽  
Ball Bearing ◽  
Point Contact ◽  
Experimental Measurements ◽  
Line Contact ◽  
Optical Analysis ◽  
Grease Lubrication ◽  
Theoretical Predictions ◽  
Pressure Stress ◽  
Starvation Conditions

Elastohydrodynamic oil film measurements for rolling point contact under starvation conditions are obtained using optical interferometry. The experimental measurements present a reasonably clear picture of the starvation phenomenon and are shown to agree with theoretical predictions. Starvation inhibits the generation of pressure and, therefore, reduces film thickness. It also causes the overall pressure, stress, and elastic deformation to become more Hertzian. Additional experiments using interferometry illustrate: the cavitation pattern, lubricant entrapment, grease lubrication, ball spin, and edge effects in line contact.

Effect of Rolling Velocity and Maximum Hertzian Pressure on Fluid Film in Steady State EHL Line Contact with Rough Surface and Linear Piezoviscosity

2014 ◽  
Vol 592-594 ◽  
pp. 1371-1375
Author(s):  
Nitesh Talekar ◽  
Punit Kumar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Film Thickness ◽  
Rough Surface ◽  
Computer Code ◽  
Fluid Film ◽  
Line Contact ◽  
Rolling Velocity ◽  
Load Carrying ◽  
Lubricated Contact

Consideration of surface roughness in steady state EHL line contact is the first step towards understanding the lubrication of rough surface problem. Current paper investigates the use of sinusoidal waviness in the contact; more precisely it gives performance of real fluid in EHL line contact. The effect of various parameters like rolling velocity (U) and maximum Hertzian pressure (ph) on surface roughness by using properties of linear and exponential piezo-viscosity is taken into consideration to evaluate behavior of pressure distribution of load carrying fluid film and film thickness. Full isothermal, Newtonian simulation of EHL problem gives described effects. Spiking or fluctuation of pressure and film thickness curves is expected to show presence of irregularities on the surface chosen and amount of fluctuation depends on certain parameters and intensity of irregularities present. Rolling side domain of-4.5 ≤ X ≤ 1.5 with grid size ∆X=0.01375 is selected. A computer code is developed to solve Reynolds equation, which governs the generation of pressure in the lubricated contact zone is discritized and solved along with load balance equation using Newton-Raphson technique.

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