Showing papers by "Satish C. Sharma published in 2013"

Analysis of externally pressurized multirecess conical hybrid journal bearing system using micropolar lubricant

Abstract: This article describes an analytical study to demonstrate the influence of micropolar lubricant on a four-pocket conical hybrid journal bearing system compensated with membrane restrictor. The modi...

A study of two lobe non recessed worn journal bearing operating with non-Newtonian lubricant:

Abstract: The present paper is aimed to investigate theoretically the effect of non-linear behavior of the lubricant on the performance of an orifice compensated two lobe non recessed worn hybrid journal bea...

Performance of hydrostatic circular thrust pad bearing operating with Rabinowitsch fluid model

Abstract: Polymer-based additives such as poly isobutylene are blended with lubricating oil to enhance the lubricating performance of the base oil. The Rabinowitsch fluid model effectively describes the infl...

A study of misaligned hole‐entry worn journal bearing operating in turbulent regime

Abstract: Purpose – The purpose of this paper is to study theoretically the combined influence of journal misalignment and wear on the performance of a hole‐entry hybrid journal bearing system The bearing is assumed to be operating in a turbulent regimeDesign/methodology/approach – The modified Reynolds equation based on Constantinescu lubrication theory has been solved by using finite element method together with orifice and capillary restrictors flow equations as a constrain together with appropriate boundary conditionsFindings – It has been observed that for a symmetric hole‐entry journal bearing configuration the value of h¯min is more for the bearing compensated by orifice restrictor as compared to capillary restrictor when bearing operates in turbulent regime under worn/unworn conditions From the point of view of stability threshold speed ω¯th, the reduction in the value of ω¯th for capillary compensated bearing is around −389 percent whereas for orifice compensated bearing it is −785 percent when misal

Vibration signature analysis of a high speed rotor supported on ball bearings due to localized defects

Abstract: This paper presents the vibration signature analysis of the high speed rolling element bearings due to localized defects with an un-cracked and a cracked rotor. In rotating machines, one of the main causes of breakdown is faults in ball bearings and crack in rotors. Thus, accurate prediction of severe vibration conditions and characteristic defect frequencies is crucial for the reliable operation. A test rig of a high speed rotor supported on healthy and defective ball bearings is used. The vibration response is obtained and analyzed for the un-cracked and cracked rotor with and without defects on bearing components. The defects such as spalls on the outer race, inner race and on the rolling elements are considered for the study. Combined parametric effects have been analyzed to predict the dynamic response of a rotor-bearing system using response surface method. It is also observed that the severe vibrations occur under bearings with spall on the inner race surface and on a ball under high speed rotor co...

Physical modelling investigation of influence of strand blockage on RTD characteristics in a multistrand tundish

Abstract: In the continuous casting process, the tundish acts as a continuous molten steel distribution vessel. The importance of the tundish during the molten steel delivery becomes more significant when it supplies liquid steel to more than one mould. In the present work, a water model of a six strand billet caster tundish has been used to study the effect of strand blockage on the residence time distribution (RTD) characteristics at the strands. All the experiments were performed under steady state conditions. Potassium chloride was used as a tracer for the study. The effects of blockage on the strand dissimilarity among the open strands were also studied. Both single and dual strand blockage experiments were performed. Blockage of strands deteriorated the RTD characteristics at the open strands. The results reveal the most preferred options for strand blockage when the plant operation needs to do so.

Effect of Resistance Training Over Aerobic Exercise in Improving Quality of Sleep in Older Adults

Abstract: Background: Lack of studies with appropriate research design and methodology on sleep improvement with exercise, it has not been possible to draw firm conclusions about the effect of resistance exercises over aerobic exercises in improving the quality of sleep in older adults. The purpose of the study was to determine the effect of resistance exercises over aerobic exercises in improving quality of sleep in community dwelling older adults thereby improving the physical fitness and preventing falls. Materials and Method: Forty five subjects with poor sleep and actively living in community were recruited for the study. Subjects were divided into three groups- Aerobic exercise, Resistance training and control group. Resistance training group received exercises like arm curls, bench press, rowing, shoulder press, leg extension and leg press. Aerobic exercise group received activities like elbow flexion, elbow extension, shoulder abduction and adduction, side stepping, cycling etc. Control group was given no training. All the subjects were treated for 5 days a week for 6 weeks and follow-up was taken after 2 weeks. Outcome measures included Pittsburgh Sleep Quality Index and Berg Balance Scale. Results: Overall, subjects in both the resistance and aerobic groups improved over 6 weeks training as compared to control group. A statistical significant difference was observed between the Resistance and Aerobic groups in Pittsburgh Sleep Quality Index. Conclusion: In subjects with poor sleep, addition of resistance training proved to be effective than Aerobic exercises in improving quality of sleep in older adults.

Tribology in Machine Components

Abstract: Proper tribological practices are extremely important from the view point of reliable and maintenance free operation of machine components. Friction, wear, and lubrication are three main domains of tribology. Proper interfacing among these domains is essential to have a better performance of machine components. Bearings are most critical machine elements which imparts constrained relative motion between two machine components. Bearings either have sliding contact or rolling contact. In the present chapter different types of bearings have been discussed. The main focus of this chapter is on hydrostatic/hybrid fluid-film journal bearings. The components of the hydrostatic/hybrid bearing system that have significant impact on bearing performance have been described. The analysis of fluid-film journal bearings and their performance characteristics parameters have been discussed. The chapter also discusses some current research trends in the design of hydrostatic/hybrid journal bearings. In concluding section the chapter discusses some of the results pertaining to the current issues of research, which needs to be considered for an accurate and realistic design of hydrostatic/hybrid journal bearing system, such as the number of recesses, type of restrictor, shape of recess, influence of turbulence and flexibility, etc.

Response Surface Method based Railway Wheel Optimisation for Natural Frequency

Abstract: In this paper, response surface method is used to find out the fatigue life equation by taking load and dimensions of the wheel as variables. The natural frequency is taken as a factor for fatigue life. An ANOVA analysis is carried out to formulate the natural frequency function. An objective function has been formulated to minimise the mass of railway wheel considering the strength and geometrical constraints of inner hub-hole, hub-web interface and hub-rim interface.