No abstract

No abstract

This paper presents a novel drum magnetorheological clutch design having a wedge shaped boundary. The converging film formed due to the direction of motion of the magnetorheological clutch and the inclination of the wedge planes helps to produce the pressure generating mechanism in the magnetorheological grease film. The resistance force developed due to this mechanism in the proposed case exceeds that of the conventional drum clutch. The proposed wedge shaped drum magnetorheological clutch consists of bimetallic discs made up of aluminium and mild steel. Mild steel disc has a certain number of inclined sliders shaped like a wedge at its boundary, which is immersed in the magnetorheological grease. The yield stress of the magnetorheological grease varies as a function of the magnetic field created by electric current passing through the electromagnet. Bingham model has been employed in the present study to analyse theoretically the torque generated by wedge-shaped drum magnetorheological clutch. The proposed magnetorheological drum clutch with wedge shaped boundary and conventional drum clutch have been designed and fabricated with similar material parameters and magnetic circuits. The experiment has been performed for the different current values (0 A, 0.25 A and 0.52 A). Torque results are plotted and compared for both cases. Experimental results suggest that the proposed wedge shaped drum magnetorheological clutch produces more torque than the conventional drum magnetorheological clutch, and thus it has better performance.

Hydrodynamic journal bearings are widely used in rotating machines where high loading condition prevails. In this work, effect of different volume fractions of TiO2 (Titanium dioxide) additive in commercially available SAE30 lubricant oil on the performance of hydrodynamic journal bearing is analysed experimentally. Hydrodynamic journal bearing test rig is used to perform the experiment. The experiment is carried out by taking different volume fractions of TiO2 additive (0.075%, 0.1% and 0.15%) in SAE30 lubricant base oil and their effect on journal bearing characteristics like coefficient of friction, pressure distribution, temperature rise, eccentricity ratio, attitude angle, minimum film thickness and displacement is analysed. Paraffin oil is used to uniformly distribute the TiO2 in the base oil and to resist sedimentation. The study shows that the addition of TiO2 additive in the base SAE30 lubricant oil is capable of significantly reducing the values of friction coefficient and maximum temperature rise. It has been found that the addition of TiO2 additive improves the performance of the hydrodynamic journal bearing. Results reveals that the additive performs better at higher loading conditions.

No abstract

No abstract