IIT Delhi Course , Prof. Harish Hirani

Lecture 1: Introduction

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Lecture Details :

Tribology by Dr. Harish Hirani, Department of Mechanical Engineering, IIT Delhi. For more details on NPTEL visit

Course Description :

INTRODUCTION : Defining Tribology,Tribology in Design - Mechanical design of oil seals and gasket - Tribological design of oil seals and gasket,Tribology in Industry (Maintenance),Defining Lubrication,Basic Modes of Lubrication,Properties of Lubricants,Lubricant Additives,Defining Bearing Terminology - Sliding contact bearings - Rolling contact bearings,Comparison between Sliding and Rolling Contact Bearings,Examples,Exercise.

FRICTION and WEAR : Friction - Laws of friction - Friction classification - Causes of friction,Theories of Dry Friction,Friction Measurement,Stick-Slip Motion and Friction Instabilities,Wear - Wear classification - Wear between solids - Wear between solid and liquid - Factors affecting,wear - Measurement of wear,Theories of Wear,Approaches to Friction Control and Wear Prevention,Boundary Lubrication,Bearing Materials and Bearing Construction,Examples,Exercise.

LUBRICATION of BEARINGS : Mechanics of Fluid Flow - Theory of hydrodynamic lubrication - Mechanism of pressure development in oil film,Two Dimensional Reynoldss Equation and its Limitations,Idealized Bearings,Infinitely Long Plane Fixed Sliders,Infinitely Long Plane Pivoted Sliders,Infinitely Long Journal Bearings,Infinitely Short Journal Bearings,Designing Journal Bearing - Sommerfeld number - Raimondi and Boyd method - Petroffs Solution - Parameters of bearing design - Unit pressure - Temperature rise - Length to diameter ratio - Radial,clearance - Minimum oil-film thickness,Examples,Exercise

HYDRODYNAMIC THRUST BEARING : Introduction - Flat plate thrust bearing - Tilting pad thrust bearing,Pressure Equation - Flat plate thrust bearing - Tilting pad thrust bearing,Load - Flat plate thrust bearing - Tilting pad thrust bearing,Center of Pressure - Flat plate thrust bearing - Tilting pad thrust bearing,Friction - Flat plate thrust bearing - Tilting pad thrust bearing,Examples,Exercise.

HYDROSTATIC and SQUEEZE FILM LUBRICATION : Hydrostatic Lubrication - Basic concept - Advantages and limitations - Viscous flow through,rectangular slot - Load carrying capacity and flow requirement - Energy losses - Optimum design,Squeeze Film Lubrication - Basic concept - Squeeze action between circular and rectangular plates -Squeeze action under variable and alternating loads,Application to journal bearings,Piston Pin Lubrications,Examples,Exercise.

ELASTO-HYDRODYNAMIC LUBRICATION : Principles and Applications,Pressure viscosity term in Reynoldss equation,Hertzs Theory,Ertel-Grubin equation,Lubrication of spheres,Gear teeth bearings,Rolling element bearings,Examples
GAS (AIR-) LUBRICATED BEARINGS : Introduction,Merits, Demerits and Applications,Tilting pad bearings,Magnetic recording discs with flying head,Hydrostatic bearings with air lubrication,Hydrodynamic bearings with air lubrication,Thrust bearings with air lubrication,Examples,Exercise.

TRIBOLOGICAL ASPECTS of ROLLING MOTION : The mechanics of tyre-road interactions,Road grip and rolling resistance,Tribological aspects of wheel on rail contact,Examples,Exercise
FINITE BEARINGS : Hydrostatic bearings,Hydrodynamic bearings,Thrust oil bearings,Porous Bearings,Foil bearings,Heat in bearings,Examples,Exercise.

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