摘要:

The dynamic stiffness method has been applied to the evaluation of the natural frequencies of rotating systems. To this purpose, a rotating “Rayleigh beam,” defined by adding the effect of the rotary inertia and the gyroscopic effects to the Bernoulli-Eider beam, has been formulated and its dynamic stiffness matrix is presented in this paper. The effects due to the presence of concentrated disks, as well as of elastic, isotropic supports, have been included in the formulation. The usual matrix assembly procedure is used in order to obtain the global dynamic stiffness matrix of the system. The natural frequencies of the system are determined by utilizing an iterative root searching technique. Numerical results, obtained for a rotor system taken from the literature on this subject, are presented.Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982012

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Although abnormal wear in EGR-Diesel engines is well known, the primary reason has not been clarified. In the present study, concentration of burnt gas, oxidation of oil, and condensed water in the spaces of the piston ring belt were investigated through both theoretical calculation and chemical analysis of the sampled gas, oil and. water, using a pipe along the linkage to obtain the samples. It was demonstrated that the burnt gat concentration with EGR was significantly higher than that without EGR and that, as a result, oil TUN and condensed water pH value were drastically decreased with EGR.

ISSN:1040-2004    

DOI:10.1080/10402009108982013

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Generalized dynamic motion of balls and cage in a ball bearing are simulated by solving the differential equations of motion under prescribed operating conditions and bearing geometry. The general cage motion is parametrically evaluated as a function of clearances both in the ball pockets and at the guide lands. The design significance of the modeling approach is demonstrated by the prediction of critical clearances which trigger certain instabilities in the cage motion. In more practical terms, the correlation between cage clearances and instability defines a wear life for the bearing under the prescribed operating conditions.Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982014

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In this research work, the effects of “O-type” cavitation on the static and dynamic characteristics of turbulent journal bearings submerged in the low viscosity lubricant are investigated theoretically. Extending an idea of “general short bearing theory” proposed by Pan to submerged turbulent journal bearings, “O-type” cavitation pattern, load carrying capacity and altitude angle are determined for a wide range of eccentricity ratio in both laminar and turbulent flow cases. In addition, under the assumption of small displacement of the journal center, the dynamic characteristics such as linearized spring and damping coefficients and whirl onset speed of rotor-bearing systems are obtained. Sample numerical results are indicated in graphic form and the relation between the “O-type” cavitation and the static and dynamic characteristics of submerged turbulent journal bearings is discussed.Presented at the 44th Annual Meeting in Atlanta, Georgia May 1–4, 1989

ISSN:1040-2004    

DOI:10.1080/10402009108982015

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The particulate magnetic disks commonly used in magnetic disk storage systems contain aluminum-oxide (Al2O3) particles to reinforce the strength of their magnetic coating. In this paper, the influence of these particles on the tribological characteristics of particulate disks is investigated using two types of ferrite materials for flying heads and particulate disks with four different levels of Al2O3content. As the Al2O3content increases, the wear mode changes from the adhesive wear to the abrasive wear. Owing to this transition, the head wear becomes increasingly severe while the durability of the particulate disk improves. Regarding the differences between ferrite materials, relatively soft Mn-Zn ferrite shows worse wear results than hard Ni-Zn ferrite. In particular, it is found that Mn-Zn fertile is worn even by the γ-Fe2O3particles of the particulate disks. In the combination of ferrite materials and particulate disks used here, an Al2O3content of around 8 percent is optimum to avoid headcrash, which is one of the most serious problems in magnetic disk storage systems.

ISSN:1040-2004    

DOI:10.1080/10402009108982016

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Under certain conditions a Jeffcot rotor supported on fluid film bearings can experience undesirable stress reversals at double the operating speed in synchronous whirl. When the damping in the hearings is not considered, the condition for complete stress reversal coincides with that for backward whirling of the disk. However, when the damping also is considered, the absolute whirl directions of the journal and the disk can be different under certain conditions. Hence, the rotor shaft may not experience backward whirl throughout its length. Under these circumstances, the relationship between complete stress reversal and backward whirling motion is ambiguous. The present investigation specifies the precise condition for complete stress reversal and identifies it with the relative backward whirling of the disk with respect to the journal.Presented at the 45th Annual Meeting In Denver, Colorado

ISSN:1040-2004    

DOI:10.1080/10402009108982017

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:1040-2004    

DOI:10.1080/10402009108982018

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A mathematical model to predict the dynamic behavior of two-phase mechanical seals, including the effects of thermal coning and face contact but, neglecting squeeze film effects, has been constructed. Numerical results for a representative seal indicate that such a seal is sensitive to finite disturbances which can trigger an oscillatory instability, even when operating at an equilibrium point with positive stiffness.Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982019

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

By using the first-order small parameter perturbation method, a form of the Reynolds equation has been derived for non-Newtonian lubricants based on the Bair & Winer's visco-plastic model. The Newton-Raphson iteration method has been adopted to obtain full numerical solutions for the line contact EHL. The changes of the slide/roll ratio, limiting shear stress and viscosity, which mainly reflect the non-Newtonian behavior of lubricants, have been widely investigated. The effects on the line contact EHL are discussed. Furthermore, the partial thermal EHL solutions have been presented for the temperature and shear stress distributions as well as the coefficients of friction on the surfaces. The results of theoretical analyses compare well with the experimental data.Presented at the 45th Annual Meeting In Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982020

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Nowadays, reducing frictional loss of gears to save energy is a big concern. There are many sources of printed information on this problem for gears, but most of them are practical specialized information and are not developed to give a generalized basic consideration. Since this kind of research has not been brought beyond such, a practical and specialized range, experiments were carried out to study the influences of tooth form, sliding velocity, load, tooth surface roughness, and viscosity of lubricating oils, and kinds of oils on the frictional loss of gears. The frictional loss of spur gears decreases with sliding velocity and the viscosity of lubricating oils, and increases with surface roughness. The frictional loss is very low when using a synthetic oil of the SHF type. The organic molybdenum friction modifier (FM) is also quite effective for reducing frictional loss. Finally, empirical formulas for calculating frictional loss were expressed in terms of tooth form, sliding velocity, tooth surface roughness, viscosity of the lubricating oil and load.Presented at the 45th Annual Meeting in Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982021

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor