Tribologia

Tribology in Machine Design

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Tribology in Machine Design

T. A. STOLARSKI
MSc, PhD, DSc, DIG, CEng, MIMechE

OXFORD AUCKLAND BOSTON JOHANNESBURG

MELBOURNE NEW DELHI

Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 A division of Reed Educational and Professional Publishing Ltd A memberof the Reed Elsevier plc group First published 1990 Reprinted 2000 © T. A. Stolarski 1990
All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except inaccordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 0LP. Applications for the copyright holder's written permission to reproduce any part of this publication should be addressed to the publishers

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Contents

Preface 1. Introduction to theconcept of tribodesign

xi 1

1.1. 1.2.

Specific principles of tribodesign Tribological problems in machine design 1.2.1. Plain sliding bearings 1.2.2. Rolling contact bearings 1.2.3. Piston, piston rings and cylinder liners 1.2.4. Cam and cam followers 1.2.5. Friction drives 1.2.6. Involute gears 1.2.7. Hypoid gears 1.2.8. Worm gears
Basic principles of tribology

4 6 6 7 8 9 10 10 1112
13

2.

Origins of sliding friction Contact between bodies in relative motion Friction due to adhesion Friction due to ploughing Friction due to deformation Energy dissipation during friction Friction under complex motion conditions Types of wear and their mechanisms 2.8.1. Adhesive wear 2.8.2. Abrasive wear 2.8.3. Wear due to surface fatigue 2.8.4. Wear due to chemical reactions 2.9.Sliding contact between surface asperities 2.10. The probability of surface asperity contact 2.11. Wear in lubricated contacts 2.11.1. Rheological lubrication regime 2.11.2. Functional lubrication regime 2.11.3. Fractional film defect 2.11.4. Load sharing in lubricated contacts 2.11.5. Adhesive wear equation 2.11.6. Fatigue wear equation 2.11.7. Numerical example

2.1. 2.2 2.3 2.4. 2.5. 2.6 2.7 2.8.13 14 15 16 17 18 18 19 19 20 21 22 23 26 31 33 33 34 37 39 40 41

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Contents

Relation between fracture mechanics and wear 2.12.1. Estimation of stress intensity under non-uniform applied loads 2.13. Film lubrication 2.13.1 Coefficient of viscosity 2.13.2. Fluid film in simple shear 2.13.3. Viscous flow between very close parallel surfaces 2.13.4. Shear stress variations within thefilm 2.13.5. Lubrication theory by Osborne Reynolds 2.13.6. High-speed unloaded journal 2.13.7. Equilibrium conditions in a loaded bearing 2.13.8. Loaded high-speed journal 2.13.9. Equilibrium equations for loaded high-speed journal 2.13.10. Reaction torque acting on the bearing 2.13.11. The virtual coefficient of friction 2.13.12. The Sommerfeld diagram References 3. 3.1. 3.2. 3.3. 3.4. 3.5. 3.6.3.7. Elements of contact mechanics Introduction Concentrated and distributed forces on plane surfaces Contact between two elastic bodies in the form of spheres Contact between cylinders and between bodies of general shape Failures of contacting surfaces Design values and procedures Thermal effects in surface contacts 3.7.1 Analysis of line contacts 3.7.2. Refinement for unequal bulk temperatures...