# TRIBOLOGY (18ME822)

## TRIBOLOGY

#### Course Learning Objectives:

• To educate the students on the importance of friction, the related theories/laws of sliding and rolling friction and the effect of viscosity of lubricants.
• To expose the students to the consequences of wear, wear mechanisms, wear theories and analysis of wear problems.
• To make the students understand the principles of lubrication, lubrication regimes, theories of hydrodynamic and the advanced lubrication techniques.
• To expose the students to the factors influencing the selection of bearing materials for different sliding applications.
• To introduce the concepts of surface engineering and its importance in tribology.

### Module-1

Introduction to tribology: Historical background, practical importance, and subsequent use in the field.
Lubricants: Types and specific field of applications. Properties of lubricants, viscosity, its measurement, effect of temperature and pressure on viscosity, lubrication types, standard grades of lubricants, and selection of lubricants.

### Module-2

Friction: Origin, friction theories, measurement methods, friction of metals and non-metals. Wear: Classification and mechanisms of wear, delamination theory, debris analysis, testing methods and standards. Related case studies.

### Module-3

Hydrodynamic journal bearings: Friction forces and power loss in a lightly loaded journal bearing, Petroff’s equation, mechanism of pressure development in an oil film, and Reynold’s equation in 2D.
Introduction to idealized journal bearing, load carrying capacity, condition for equilibrium, Sommerfeld’s number and it’s significance; partial bearings, end leakages in journal bearing, numerical examples.

### Module-4

Plane slider bearings with fixed/pivoted shoe: Pressure distribution, Load carrying capacity, coefficient of friction, frictional resistance in a fixed/pivoted shoe bearing, center of pressure, numerical examples.
Hydrostatic Lubrication: Introduction to hydrostatic lubrication, hydrostatic step bearings, load carrying
capacity and oil flow through the hydrostatic step bearing, numerical examples. Introduction to Hydrostatic journal bearings.

### Module-5

Bearing Materials: Commonly used bearings materials, and properties of typical bearing materials.
Advantages and disadvantages of bearing materials. Introduction to Surface engineering: Concept and scope of surface engineering. Surface modification – transformation hardening, surface melting, thermo chemical processes. Surface Coating – plating, fusion processes, vapor phase processes. Selection of coating for wear and corrosion resistance.

#### Course Outcomes: At the end of the course, the student will be able to:

CO1: Understand the fundamentals of tribology and associated parameters.
CO2: Apply concepts of tribology for the performance analysis and design of components experiencing relative  motion.
CO3: Analyse the requirements and design hydrodynamic journal and plane slider bearings for a given
application.
CO4: Select proper bearing materials and lubricants for a given tribological application.
CO5: Apply the principles of surface engineering for different applications of tribology.

#### Question paper pattern:

• The question paper will have ten full questions carrying equal marks.
• Each full question will be for 20 marks.
• There will be two full questions (with a maximum of four sub- questions) from each module.
• Each full question will have sub- question covering all the topics under a module.
• The students will have to answer five full questions, selecting one full question from each module.

#### Textbook:

1 Introduction to Tribology B. Bhushan John Wiley & Sons, Inc., New York 2002
2 Engineering Tribology Prasanta Sahoo PHI Learning Private Ltd, New Delhi 2011
3 Engineering Tribology J. A. Williams Oxford Univ. Press 2005

#### Reference Books:

1 Introduction to Tribology in bearings B. C. Majumdar Wheeler Publishing
2 Engineering Tribology G. W. Stachowiak and A. W. Batchelor Butterworth-Heinemann 1992
3 Friction and Wear of Materials Ernest Rabinowicz John Wiley &Sons 1995
4 Basic Lubrication Theory A. Cameron Ellis Hardwoods Ltd., UK
5 Handbook of tribology: materials, coatings and surface treatments