An Introduction to Aircraft Structural Analysis - Megson T.H.G.pdf

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An Introduction to Aircraft
Structural Analysis
T. H. G. Megson
AMSTERDAM BOSTON HEIDELBERG LONDON
NEW YORK OXFORD PARIS SAN DIEGO
SAN FRANCISCO SINGAPORE SYDNEY TOKYO
Butterworth-Heinemann is an imprint of Elsevier
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Copyright © 2010, T. H. G. Megson. Published by Elsevier Ltd. All rights reserved.
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British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library.
Library of Congress Cataloging-in-Publication Data
Megson, T.H.G. (Thomas Henry Gordon)
An introduction to aircraft structural analysis / T.H.G. Megson.
p. cm.
Rev. ed. of: Aircraft structures for engineering students / T.H.G. Megson. 4th ed. 2007.
Includes bibliographical references and index.
ISBN 978-1-85617-932-4 (alk. paper)
1. Airframes. 2. Structural analysis (Engineering) I. Title.
TL671.6.M36 2010
629.134’31–dc22
2009050354
For information on all Butterworth-Heinemann publications
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Printed in the United States of America
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Contents
Preface ............................................................................................. vii
PART A FUNDAMENTALS OF STRUCTURAL ANALYSIS
CHAPTER 1 Basic Elasticity ........................................................................... 3
1.1 Stress .................................................................................................. 3
1.2 Notation for Forces andStresses ................................................................... 5
1.3 Equations of Equilibrium ........................................................................... 7
1.4 Plane Stress ........................................................................................... 9
1.5 Boundary Conditions ................................................................................ 9
1.6 Determination of Stresses on InclinedPlanes .................................................... 10
1.7 Principal Stresses .................................................................................... 14
1.8 Mohr’s Circle of Stress .............................................................................. 16
1.9 Strain .................................................................................................. 20
1.10 Compatibility Equations ............................................................................ 24
1.11 Plane Strain ........................................................................................... 25
1.12 Determination of Strains on InclinedPlanes...................................................... 25
1.13 Principal Strains...................................................................................... 27
1.14 Mohr’s Circle of Strain .............................................................................. 28
1.15 Stress–StrainRelationships ......................................................................... 28
1.16 Experimental Measurement of Surface Strains ................................................... 37
Problems .............................................................................................. 41
CHAPTER 2
Two-Dimensional Problems in Elasticity .............................................. 45
2.1
Two-Dimensional Problems ........................................................................ 45
2.2
Stress Functions...................................................................................... 47
2.3
Inverse and Semi-Inverse Methods ................................................................ 48
2.4
St. Venant’s Principle................................................................................ 53
2.5
Displacements ........................................................................................ 54
2.6
Bending of an End-Loaded Cantilever ............................................................ 55
Problems .............................................................................................. 60
CHAPTER 3
Torsion of Solid Sections ............................................................... 65
3.1
Prandtl Stress Function Solution ................................................................... 65
3.2
St. VenantWarpingFunctionSolution ............................................................ 75
3.3
TheMembraneAnalogy ............................................................................ 77
3.4
Torsion of a Narrow Rectangular Strip ............................................................ 79
Problems .............................................................................................. 82
CHAPTER 4 Virtual Work and Energy Methods ..................................................... 85
4.1 Work................................................................................................... 85
4.2 Principle ofVirtualWork ........................................................................... 86
4.3 Applications of the Principle ofVirtualWork .................................................... 99
Problems .............................................................................................. 107
CHAPTER 5
Energy Methods .......................................................................... 111
5.1
Strain Energy and Complementary Energy ....................................................... 111
5.2
The Principle of the Stationary Value of the Total Complementary Energy .................. 113
iii
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iv
Contents
5.3 Application to Deflection Problems ............................................................... 114
5.4 Application to the Solution of Statically Indeterminate Systems............................... 122
5.5 Unit LoadMethod ................................................................................... 138
5.6 FlexibilityMethod ................................................................................... 141
5.7 Total Potential Energy............................................................................... 147
5.8 The Principle of the StationaryValue of theTotal Potential Energy........................... 148
5.9 Principle of Superposition .......................................................................... 151
5.10 TheReciprocal Theorem............................................................................ 151
5.11 TemperatureEffects ................................................................................. 156
Problems .............................................................................................. 158
CHAPTER 6 Matrix Methods ........................................................................... 169
6.1 Notation ............................................................................................... 170
6.2 StiffnessMatrix for anElastic Spring ............................................................. 171
6.3 StiffnessMatrix for TwoElastic Springs inLine................................................. 172
6.4 Matrix Analysis of Pin-jointed Frameworks ...................................................... 176
6.5 Application to Statically Indeterminate Frameworks ............................................ 183
6.6 Matrix Analysis of Space Frames .................................................................. 183
6.7
Stiffness Matrix for a Uniform Beam.............................................................. 185
6.8
Finite Element Method for Continuum Structures ............................................... 193
Problems .............................................................................................. 211
CHAPTER 7
Bending of Thin Plates .................................................................. 219
7.1
PureBending of ThinPlates........................................................................ 219
7.2
Plates Subjected toBending andTwisting ........................................................ 223
7.3
Plates Subjected to aDistributedTransverseLoad............................................... 227
7.4
Combined Bending and In-Plane Loading of a Thin Rectangular Plate ....................... 236
7.5
Bending of Thin Plates Having a Small Initial Curvature ....................................... 240
7.6
EnergyMethod for theBending of ThinPlates .................................................. 241
Problems .............................................................................................. 250
CHAPTER 8
Columns ................................................................................... 253
8.1
Euler Buckling of Columns......................................................................... 253
8.2
InelasticBuckling.................................................................................... 259
8.3
Effect of Initial Imperfections ...................................................................... 263
8.4
Stability of Beams under Transverse and Axial Loads .......................................... 266
8.5
EnergyMethod for theCalculation of BucklingLoads inColumns ........................... 270
8.6
Flexural–Torsional Buckling of Thin-Walled Columns ......................................... 274
Problems .............................................................................................. 287
CHAPTER 9
Thin Plates ................................................................................ 293
9.1
Buckling of ThinPlates ............................................................................. 293
9.2
InelasticBuckling of Plates......................................................................... 296
9.3
Experimental Determination of Critical Load for a Flat Plate.................................. 298
9.4
Local Instability ...................................................................................... 299
9.5
Instability of Stiffened Panels ...................................................................... 300
9.6
Failure Stress in Plates and Stiffened Panels...................................................... 302
9.7
Tension Field Beams ................................................................................ 304
Problems .............................................................................................. 320
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