When the shaft current passes through the bearing under lubrication condition, the arc often occurs and the pitting can be observed on the surface of bearing. Consequently, the life of bearing is shortened. The pitting resulting from discharge is dependent upon the shaft voltage, the oil film thickness, and the insulation of lubricant. To simulate the pitting, the dynamic pitting tester is developed to investigate the effects of the kinematics parameters on the electrical pitting formation mechanism for the common material of bearing by changing the supply voltage current and the oil film thickness. Result show that in the static condition, since the arc action causes the surface melting of two specimens, and the actions of coulomb force and electrostatic force cause the specimens to attract each other, the plateau can be observed on the surfaces of specimens. The plateau is like a bridge to connect two specimens. In this moment the plateau accumulates continuously and causes two specimens to produce the repulsive force. In the dynamic condition, the formation of pitting at the initial stage is quite similar to that in the static condition. Since the effect of sliding speed, the bridge is sheared and the friction force increases. Under the actions of joule heat and friction force, the surfaces of two specimens melt and scratch continuously. When the dynamic pitting occurs, the pitting width of square specimen, the normal force and the friction force increases with increasing supply voltage, supply current, and oil film thickness. When the interface power is larger, the melting phenomenon is more obvious, and the pitting width becomes larger. Because the surface melting and the actions of Coulomb force and electrostatic force cause the material accumulates continuously, the normal force and the friction force increase with increasing the interface power. To investigate all effects of experimental parameters on the pitting width, the empirical formula for the pitting width is established in terms of supply voltage, supply current, and oil film thickness. This formula can be used to predict oil film thickness or the size of pitting width on the bearing surface for diagnosing the lubricant condition of bearing.

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1938. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed April 27, 2010) Includes bibliographical references (p. 40) and index (p. 41-45).

Many golf firms of carbon fiber golf shafts are much concerned about for standard measurement of shafts for their specific needs. To achieve the purpose, the present study was conducted. Flex¡GThe researcher first hanged a mass on the tip with the butt fixed, and then he hanged a mass on the butt with the tip fixed for measuring the deflection of the shaft. Torque¡GThe degree of torsion is measured by applying the twisting moment 0.126 (kgf•m) to the tip. Vibration¡GThe cycle per minute is measured by adding a mass to the tip of a shaft and shaking it. The mechanical performance of carbon fiber composite is modeled and solved by the finite element software ¡§ANSYS¡¨ in static and modal analysis. The errors between the simulations and experiments were compared and discussed. Finally, the angles of in, middle, and out layers of the shaft were changed to see how they affect the mechanical performance of golf shafts. In this study, the errors of the results for deflection, degree of torsion, and cycle per minute of golf shafts between experiments and simulations are less than 10%. The results solved by the finite element software ¡§ANSYS¡¨ are reliable. The results of simulations also show that a close relationship between the mechanical performance of golf shafts and the fiber angles. Eventually, a series of data bases and trend pictures were provided for golf firms' reference and application.

The principle concern of this work is the design of a lathe attachment for grinding non-circular 'polygonal' shaped workpieces suitable for use as torque transmitting machine elements. In the course of the work substantial attention is also given to the general theory and development of computer aided error analysis procedures for planar linkage mechanisms. A further smaller part of the work investigates the torsion of polygonal shafts. The non-circular shapes considered here may be loosely defined as polygonal profiles. Their application is in torque transmitting couplings for which they represent an alternative to keyed and splined couplings, although, in comparison to keys and splines, their application has been limited, mainly due to the specialised nature of their manufacture. The main objective of this work is to investigate suitable profiles and the means for their production using an attachment which can be mounted on a conventional machine tool, such as a lathe or grinding machine. The work progresses from initial consideration of shapes produced by various geometric generating methods and conception of an 'ideal' profile generating linkage mechanism through to detailed design of a precision, polygonal profile grinding, lathe attachment, and final assessment of its feasibility based on a profile precision criterion. In order to assess the precision of the attachment, computer-aided procedures are developed, after consideration of existing error analysis methods and their limitations for use in this case. These consider the various effects of tolerances, clearances and deflections upon mechanism output. As a coincidental investigation, the mechanical behaviour and strength of polygonal shaft-hub connections is reported. In particular, the torsion of a polygonal bar is theoretically analysed, using a stress function method, to determine maximum shear stresses.

No description available.

No description available.

Abstract The electrical pitting often occurs at the bearing of the ro-tating machinery due to the actions of the shaft voltage and the shaft current resulting in the arcing effect on the lubricated surface and causing the bearing failure. Since the mechanism of the electrical pitting cannot be microscopically observed in process, it is difficult to prevent the bearing damage. Hence, this study uses a static electrical pitting tester with sub -micrometer accuracy to experimentally investigate the effects of supply voltage, supply current, oil film thickness, and ad-ditive on the threshold condition of electrical pitting under the conventional bearing material pairs. Moreover, according to the SEM micrograph and EDS analysis, the mechanism of the pitted surfaces is investigated. According to the experimental results and the surface ob-servations of steel/steel pair using a paraffin base oil, three electrical pitting regimes are found under the influences of shaft voltage and oil film thickness, namely, pitting, transition, and no-pitting regimes. In the electrical pitting regime, the interface voltage, interface impedance, and interface power increases slightly with increasing oil film thickness at a certain supply current. However, the interface voltage and interface power increases with increasing supply current, and the inter-face impedance decreases with increasing supply current at a certain film thickness. Furthermore, the pitting area versus the interface power relationship is a cubic function. According to the experimental results and the surface ob-servations of babbitt alloy/steel pair using a paraffin base oil, two electrical pitting regimes are found under the influences of shaft voltage, oil film thickness, and melting point of material, namely, pitting and no-pitting regimes. The mechanism of electrical pitting on the babbitt alloy surface is significantly influenced by the interface power and the oil film thickness. At the smaller oil film thickness, the eroded surface of babbitt alloy exhibits a concave crater with a few micro-porosity in the vicinity of center region with a plateau on its surrounding, especially at high supply current. The polished track can be observed at the plateau. A large amount of tin element trans-fers to the steel ball surface because the molten tin contacts the ball. At the higher oil film thickness, only a little amount of metal element transfers to each other. The major pitting area of the babbitt alloy is caused at the initial stage of the arc dis-charge. With increasing arc discharge time, the pitting area increases slightly, and finally reaches a saturated value. According to the experimental results and the surface ob-servations of babbitt alloy/steel pair using an additive of MoS2 in a paraffin base oil, two electrical pitting regimes are found under the influences of shaft voltage, oil film thickness, and particle concentration of additive, namely, pitting and no-pitting regimes. The area of pitting regime increases with increasing additive concentration and supply current. Fur-thermore, the ratio of pitting area to the interface power in-creases with increasing additive concentration and supply current at the oil film thickness smaller than 6 mm. However, this ratio increases rapidly to about 10 times with increasing additive concentration and supply current as the oil film thickness increases from 6 mm to 10 mm. This results from the molten plateau that directly connects two specimens, and the interface power is mainly consumed at the heating of the pla-teau and the interfacial materials. According to the above re-sults, the growth model of the plateau on the pitting surface is proposed at the lubricated condition using an additive of MoS2 in paraffin base oil.

The effect of excess gravity on bone-forming elements of the growing perichondrial shaft of embryonic chicks was investigated through the use of the transmission electron microscope and various cytochemical techniques.

Thesis (M.Ing. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2007.

No description available.