In this work, a profile modification technique was used in design of a spur gear. In this technique, the tooth-sum is varied to obtain the desired contact ratio and low contact stress for a specified center distance. A program has been developed using C language to compute the contact stresses by varying the amount of profile shift for a tooth-sum of 100 teeth ( §4%). The selected tooth-sum of 96, 100, and 104 gears was subjected to cyclic loading using a back-to-back test rig. The morphology of the damaged gear tooth surface after cyclic loading was examined by scanning electron microscopy. The morphological investigation reveals that the degree of damage observed in negative number of teeth alterations is less compared to standard and positive alteration tooth-sum due to lower contact stress.
This study presents a steady state and transient solution for a finite width two-lobe bearing operating with a non-Newtonian lubricant, obeying the power law model. A non-linear time-transient analysis is carried out and the orbital stability of journal is ensured by solving the equation of motion by fourth order Runge-Kutta method. Using the expressions for eccentricity ratio of lower and upper lobes and film thickness for each lobe, the modified Reynolds equation is solved separately for each lobe by finite difference technique with a successive over-relaxation scheme. Performance parameters of two-lobe bearing like load carrying capacity, Sommerfeld number, attitude angle; flow and friction parameter are determined and compared with the established results for Newtonian lubricants. Stability parameters are compared with circular bearings. It is found that the non-Newtonian effects are very prominent in the determination of load capacity, flow and friction characteristics of two-lobe bearings. Stability parameters of two-lobe bearings are considerably higher for all eccentricity ratios compared to circular bearings; hence these bearings are better suited for applications where whirl instability limits the speed at which the bearing can be operated.
The purpose of this paper is to study the effect of non-Newtonian lubricant on the stability of oil film journal bearings mounted on flexible support using linear perturbation technique. The model of non-Newtonian lubricant developed by Dien and Elrod is taken into consideration. The dynamic co-coefficients are calculated for different values of power law index and length to diameter ratio. These are then used to find stability margin for different support parameters to study the effect of the non-Newtonian lubricant.
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