Esayo De Fatiga

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FATIGUE TESTING AND ANALYSIS OF RESULTS

by W. WEIBULL
BOCKAMOLLAN BRöSARPS STATION SWEDEN

PublishedJhr and on behalfof
ADVISORY GROUP FOR AERONAUTICAL RESEARCH AND DEVELOPMENT N( )RTH ATLANTIC TREATY ORGANIZATION

by

PERGAMON PRESS
OXFORD• LONDON• NEW YORK~PARIS 1961

PERGAMON PRESS LTD.
Headington Hill Hall, Oxford 4 & 5 Fitzroy Square, London W.1PERGAMON PRESS INC. 122 East 55th Street, New York 22, N.Y.
Statler Center 640, 900 Wilshire Boulevard Los Angeles 17, Cal jfornia

T4

PERGAMON PRESS S.A.R.L. 24 Rue des Ecoles, Paris Fe PERGAMON PRESS G.m.b.H. Koiserstrasse 75, Frankfurt am Main

/

77/
TO DERYCK C. SMITH 1916— 1959
Executive — Structures and Materials Panel Advisory Group for Aeronautical Research and Development NorthAtlantic Treaty Organization

Copyright

©
1961
ADVISORY GROUP FOR

AERONAUTICAL RESEARCH AND DEVELOPMENT NORTH ATLANTIC TREATY OROMQSZATIDN

Library of Congress Card No. 59—14498

Set in Baskervilte 10 on 11 Pt. and printed in Northern Ireland at TEE UNIVERSITIES PRESS, BELFAST

CONTENTS
PAGE FOREWORD CHAPTER
.. . .

xiii

I.

SYMBoLS AND NOMENCLATURE
.. .. .. .. .. .. .. .. .. .. . . .. .. . . . . ..

10. General 11. Applied stress cycles .. 12. Strengths End fatigue limits 13. Fatigue life and numbers ofcycles 14. Statistical quantities and mathematical signs 15. Types ofapplied load cycle 16. Variable-stress level tests
CHAPTER II. FATIGUE TESTING METHOG5

3 4
4 5 5 6

20. General .. .. 21. Routine tests .. 21.1. All-failed tests . . . . . . . . . .21.2. Fraction-failed tests .. .. .. 22. Short-life tests .. .. .. 22.1. Constant-stress amplitude tests .. 22.2. Constant-strain amplitude tests .. .. .. 23. Long-life tests .. .. .. 23.1. Response tests . . . . 23.11. The probit method .. .. .. .. 23.12. The staircase method .. .. 23.2. Increasing-amplitude tests .. .. 23.21. Step tests .. .. .. 23.22. The Prot tests .. .. .. .. 24.Cumulative-damage tests .. .. .. 24.1. Preloading tests .. 24.2. Prestressing tests . . . . . . .. 25. Service-simulating tests .. 25.1. Prograsame tests .. .. .. 25.2. Speclrtlm tests . . . . 26. Abbreviated nod accelerated tests . . . . . . 27. Methods for detenniaing crack initiation and etaek propagation 27.1. Non-,Irstroetive tests . . . . . . . . 27.2. Destructive tests . . . . . . . .
CHAPTER

7 10 1112 13 14 15 15 15 15 16 17 17 18 18 19 19 20 20 21 21 22 23 24

III.

FATIGUE lEtTING MACITIrsE5 AND EQUIPMENTs

30. General .. .. .. .. 31. Machines for general purposes .. .. 31.1. Axial loading .. .. .. 31.11. Load produced by mechanical deflexion and variable springs and/or masses .. .. .. .. 31.12. Load produced by dead Weights and/or constant spring forces .. 31.13. Load produced bycentrifugal forces .. .. 31.14. Load produced by electro-magnetie forces .. .. 31.15. Load produced by hydraulic forces .. .. .. 31.16. Load produced by pneumatic forces .. .. 31.17. Load produced by thermal dilatation .. ..
vst

25

26
26 26 28 28 29 29 30 30

CONTENTS

CONTENTS 31 31 32 32 33 34 34 34 34 35 36 36 37 37 37 41.3. Photo-electric instruments and devices .. .. .. 41.4.Optical instruments and devices .. .. 41.5. Pneumatic instruments and devices .. .. .. Strain-measuring instruments and devices .. .. .. 42.0. General .. .. .. 42.1. Meelsanical instruments and devices .. 42.2. Electrical instruments and devices based on measurement ofresistance .. 42.3. Optical instruments and devices .. .. .. .. Load-measuring instruments and devices .. .. .. 43.0. General .. .... 43.1. Mechanical instruments and devices .. .. .. 43.2. Electrical instruments aud devices .. .. .. .. .. .. 43.21. Based on measurement of resistance 43.22. Based on measurement ofinductance or capacitance 43.3. Piezo-electric instruments and devices .. .. 43.4. Optical instruments and devices .. .. .. .. Stress-measuring instruments and devices .. .. .. 44.0. General .. .. .. 44.1. Optical...