Reliability and wear analysis and lubricant selection- a structural approach

RELIABILITY WEAR ANALYSIS AND ICU RICANT SELECTION

— A STRUCTURAL APP OACH

by

OM PARKASH GANDHI

Department of Mechanical Engineering

Thesis Submitted

in fulfilment of the requirements of the degree of

DOCTOR OF PHILOSOPHY

to the

INDIAN INSTITUTE OF TECHNOLOGY, DELHI

INDIA April, 1991

1CG1U

1c iftc

rip

'7d4ct-ti -Lcr-

CERTIFICATE

This is to certify that the thesis entitled "Reliability

& Wear analysis and lubricant selection - A Structural Approach" being submitted by Mr. Om Parkash Gandhi to the Indian Institute of Technology, Delhi for the award of Doctor of Philosophy, is a record of bonafide research work carried out by him. He has worked under our guidance and supervision and fulfilled the requirement for the submission of this thesis, which to our knowledge, has reached the requisite standard.

The results contained in this thesis have not been submitted to any other University or Institute for the award of any degree or diploma.

\044=-Pv-v

(Dr.K.S.SHISHODIA) (Dr.V.P.AGRAWAL)

Associate Professor Professor

Deptt. of Applied Mechanics Deptt. of Mechanical Engg.

Indian Institute of Technology, Hauz Khas, New Delhi-110 016,

INDIA.

(i)

ACKNOWLEDGEMENTS

I am very fortunate to have been associated with Prof. V.P.Agrawal and work under his able guidance on this thesis. No amount of words can really suffice in expressing my sincere thanks to him for his constant support, encouragement, enthusiasm and patience.

I feel obliged to my co-supervisor Prof.K.S.Shishodia for his encouragement and guidance throughout the duration of the work.

I express my sincere thanks to Prof.B.C.Nakra, Prof.O.P.Chawla, Prof.A.Sethuramiah, Prof.K.N.Gupta and Dr.V.A.Eshwar for their encouragement.

Thanks are due to my colleague Late Mr.Arun Prakash for his immense help.

I also wish to thank all my colleagues and friends for their excellent cooperation at all times.

I am thankful to Mr.A.Balachandran and Mr.Ashok Vashistha for word processing the thesis with great interest and accuracy.

My special thanks to Mr.Rajesh Bhat for his cooperation.

I am also thankful to Mr.J.C.Tuteja for drawing the figures neatly and patiently.

Finally my appreciation goes to my wife Renu and daughters Anu Shilpa and Minu Shikha for their cheerful company which helped me to work in a creative atmosphere.

OM PAR SH GANDHI

(iv ABSTRACT

A unified Structural approach based on graph theory and matrix methods is developed for structure, reliability, failure and wear analysis, and lubricant evaluation and selection. The structure of a system is represented as a linear graph. The matrix representation of the system structure graph is used to develop multinomial functions by associating suitable attributes of reliability, failure, wear and lubricant with the graph and matrix elements. The multinomial functions of reliablity, failure, wear and lubricant are developed for Characterization and analysis of the system.

Identification set for characterizing the system based on structure, reliability and wear are developed for mechanical and hydraulic systems. Reliability, failure, wear and lubricant indices are obtained from multinomial functions for classification and characterization of the systems.

The procedure is shown to be useful for analysis and evaluation of the system, comparison and optimum selection of the system structure at the conceptual stage of design, in absence of the information about salient features of the system. The method permits identification and analysis of critical subsystems, their connections, paths and loops. The fault diagnosis and identification of weak components/subsystems are carried out for

the improvement of the system. The method is equally applicable at operating state and failed state.

(v)

CONTENTS

Page No:

CERTIFICATE ( i)

ACKNOWLEDGMENTS (ii)

ABSTRACT (iv)

CONTENTS (v)

NOMENCLATURE (vii)

LIST OF FIGURES (xi)

LIST OF TABLES (xiii)

CHAPTER-I INTRODUCTION 1 CHAPTER-II LITERATURE SURVEY 8

2.1 SYSTEM RELIABILITY 9

2.2 WEAR EVALUATION 22

2.3 LUBRICANT EVALUATION AND SELECTION 32

2.4 SYSTEM STRUCTURE 38

2.5 GRAPH THEORETICAL MODELING 48 CHAPTER-III SYSTEM STRUCTURE MODEL 58

3.1 SYSTEM STRUCTURE GRAPH 59

3.2 MATRIX REPRESENTATION OF SYSTEM STRUCTURE

GRAPH 65

3.3 STRUCTURE IDENTIFICATION AND COMPARISON 76 3.4 VARIABLE PERMANENT SYSTEM STRUCTURE MATRIX 77

3.5 STRUCTURAL ANALYSIS 81

3.6 COMPARISON OF SYSTEMS 83

CHAPTER-IV RELIABILITY EVALUATION AND ANALYSIS 87

4.1 RELIABILITY GRAPH 92

4.2 MATRIX REPRESENTATION OF RELIABILITY GRAPH 94 4.3 VARIABLE PERMANENT RELIABILITY FUNCTION 101 4.4 RELIABILITY ANALYSIS 104 4.5 SELECTION OF OPTIMUM RELIABLE SYSTEM 111

4.6 EXAMPLE I 112

4.7 RELIABILITY OF LARGE SYSTEMS 122 4.8 RELIABILITY GRAPH INVARIANTS 123 4.9 COMPOSITE RELIABILITY INDEX 133 4.10 SYSTEM IDENTIFICATION 135 4.11 MODIFIED RELIABILITY MEASURES 135 4.12 MODIFIED SYSTEM IDENTIFICATION 141

4.13 EXAMPLE-II 141

(vi)

CHAPTER-V FAILURE ANALYSIS AND RELIABILITY

IMPROVEMENT 148

5.1 FAILURE MODE AND EFFECTS ANALYSIS 148 5.2 FAILURE MODE AND EFFECTS INTERACTIONS 149 5.3 FAILURE MODE AND EFFECTS MATRIX 155 5.4 FAILURE MODE AND EFFECTS - ANALYSIS AND TESTS 166 5.5 FAILURE MODE AND EFFECTS INDEX 171 5.6 EXAMPLE: DOMESTIC HOT WATER SYSTEM 177 5.7 FAILURE EFFECTS ANALYSIS 185 5.8 FAILURE CAUSE ANALYSIS 190 5.9 FAILURE CAUSALITY MATRIX 195 5.10 VARIABLE FAILURE CAUSALITY PERMANENT MATRIX 203 5.11 VARIABLE CAUSE - ANALYSIS AND TESTS 205 5.12 FAILURE CAUSE IDENTIFICATION 209 CHAPTER-VI WEAR MODELING AND ANALYSIS 213

6.1 WEAR COMPLEXITY AND ITS MODELING THROUGH

DIGRAPH 214

6.2 WEAR MATRICES 220

6.3 WEAR ANALYSIS 229

6.4 WEAR CHARACTERIZATION AND ISOMORPHISM 233

6.5 SYSTEM WEAR INDEX 235

6.6 EXAMPLE 237

6.7 SUBSYSTEM WEAR MEASURE 243 6.8 WEAR INTERDEPENDENCE BETWEEN COMPONENTS 249 6.9 EVALUATION OF SYSTEM WEAR INDEX 255 CHAPTER-VII LUBRICANT EVALUATION AND SELECTION 259 7.1 FACTORS INFUENCING LUBRICANT SELECTION 260

7.2 METHODOLOGY 262

7.3 LUBRICANT ATTRIBUTES 263 7.4 LUBRICANT ATRRIBUTES DIGRAPH 267 7.5 ATTRIBUTES RELATIVE IMPORTANCE MATRIX 270 7.6 LUBRICANT SELECTIVITY INDEX 279 7.7 LUBRICANT SELECTION PROCEDURE 282 7.8 EXAMPLE: SELECTION OF LUBRICANT FOR

GRINDING OPERATIONS 286

CHAPTER-VIII CONCLUSION AND SCOPE FOR FUTURE WORK 296

REFERENCES 303

BIO-DATA 318