الفهرس 
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Abstract
Externally pressurized conical bearing with a central recess is considered, both analytically and experimentally. An analysis is made to
predict the dynamic characteristics namely, the dynamic stiffness and
damping coefficient of the bearing. The Reynolds equation for the fluid film and recess flow continuity equation are linearized by using perturbation technique for small amplitude of oscillations. The effects of different design and operating parameters are taken into consideration. These include recess radius ratio (rj), the frequency of oscillation presented as squeeze number (0), cone angle (a), the fluid inertia due to rotation presented as speed parameter (5), recess volume fluid compressibility presented as the recess volume fluid compressibility parameter (y) and type of compensation restrictor. Namely, capillary, orifice and constant flow valve are considered. The analysis is conducted for constant and variable film thickness of
. Newtonian and non-Newtonian fluid lubricants. The analysis for plane thrust circular bearing become readily found by making the semicone angle equal to 90°. On the experimental side, investigations are made on a deep recess conical bearing, of recess radius ratio 0.47 and cone angle (a=300), supplied with water as a lubricant. The dynamic characteristics wer~ obtained from recorded free vibration signals that result after a shock load. The standard logarithmic decrement technique is then used to determine the dynamic stiffness and damping coefficient in a nondimensional form. The results of the analytical study show that the dynamic stiffness is . strongly dependent on the squeeze number whether the recess volume compressibility effect is considered or neglected. Meanwhile, the damping
coefficient is shown to be independent of the squeeze number if the recess volume fluid compressibility is neglected. However, when fluid compressibility is taken into consideration, the damping coefficient is reduced by increasing the squeeze number. The reduction in damping coefficient is more pronounced for high squeeze numbers (0) 100).
It was found that the conical bearing dimensions (recess radius ratio,
? and cone angle) and type of compensation (capillary, orifice and constant
flow valve) have a marked influence on the dynamic performance of the bearing.
The analysis shows that considering the rotational inertia term has a profound influence on the bearing dynamic performance” depending on bearing dimensions and squeeze number.
In the case of variable film thickness conical bearing, the gap angle is found to have significant effects on the dynamic stiffness and damping coefficient for various values of squeeze number. Using non-Newtonian lubricant films in conical bearing results in a ”pronounced influence of the behaviour index (n) on the dynamic performance characteristics. It is found that decreasing the behaviour index (n) decreases both the dynamic stiffness an~ damping coefficient for different values of squeeze number. The results of the experimental investigation show that the dynamic
” stiffness is highly dependent on the squeeze and Reynolds numbers while the damping coefficient is independent of these parameters. Meanwhile, both the dynamic stiffness and damping coefficient are strongly influenced by the lubricant film thickness.