CONTENTS
Preface xiii
Preface to the First Edition xv
1 Characteristics of Aircraft Structures and Materials 1
1.1 Introduction / 1
1.2 Types of Aircraft Structures / 1
1.2.1 Fixed-wing Aircraft / 1
1.2.2 Rotorcraft / 2
1.2.3 Lighter-than-air Vehicles / 2
1.2.4 Drones / 2
1.3 Basic Structural Elements in Aircraft Structure / 3
1.3.1 Fuselage / 3
1.3.2 Wing / 3
1.3.3 Landing Gear / 3
1.3.4 Control Surfaces / 4
1.4 Aircraft Materials / 4
Problems / 6
2 Loads on Aircraft Structures 7
2.1 Introduction / 7
2.2 Basic Structural Elements / 7
2.2.1 Axial Member / 7
2.2.2 Shear Panel / 8
2.2.3 Bending Member (Beam) / 9
2.2.4 Torsion Member / 10
2.3 Wing and Fuselage / 11
2.3.1 Load Transfer / 11
2.3.2 Wing Structure / 12
2.3.3 Fuselage / 13
Problems / 15
3 Introduction to Elasticity 18
3.1 Introduction / 18
3.2 Concept of Displacement / 19
3.3 Strain / 21
3.4 Stress / 26
3.5 Equations of Equilibrium in a Uniform Stress Field / 28
3.6 Equations of Equilibrium in a Nonuniform Stress Field / 30
3.7 Stress Vector-Stress Component Relations / 32
3.8 Principal Stress / 34
3.9 Shear Stress / 37
3.10 Stress Transformation / 39
3.11 Linear Stress-Strain Relations / 41
3.11.1 Strains Induced by Normal Stress / 42
3.11.2 Strains Induced by Shear Stress / 45
3.11.3 Three-Dimensional Stress-Strain Relations / 46
3.12 Plane Elasticity / 51
3.12.1 Stress-Strain Relations for Plane Isotropic Solids / 51
3.12.2 Stress-Strain Relations for Orthotropic Solids in Plane Stress / 54
3.12.3 Governing Equations / 55
3.12.4 Solution by Airy Stress Function for Plane Isotropic Solids / 58
3.12.5 Plane Elasticity Solutions in Polar Coordinate System / 60
3.13 Formulations Beyond 2D Plane Elasticity / 64
Problems / 66
4 Torsion 74
4.1 Introduction / 74
4.2 Torsion of Uniform Bars with Arbitrary Cross-section/ 75
4.2.1 Governing Equations / 75
4.2.2 Boundary Conditions / 78
4.3.3 Torque-Stress Relations / 79
4.3.4 Warping Displacement / 80
4.3.5 Torsion Constant / 80
4.3 Bars with Circular Cross-Sections / 81
4.3.1 Elasticity Approach using Prandtl Stress Function / 81
4.3.2 Mechanics of Solid Approach / 84
4.4 Bars with Narrow Rectangular Cross-Sections / 87
4.5 Closed Single-Cell Thin-Walled Sections / 91
4.5.1 The s-n coordinate system / 91
4.5.2 Prandtl Stress Function / 93
4.5.3 Shear Flow q / 94
4.5.4 Shear Flow - Torque Relation / 95
4.5.5 Twist Angle / 96
4.5.6 Torsion Constant J / 99
4.6 Multicell Thin-Walled Sections / 102
4.7 Warping in Open Thin-Walled Sections / 107
4.8 Warping in Closed Thin-Walled Sections / 111
4.9 Effect of End Constraints / 113
Problems / 120
5 Bending and Flexural Shear 126
5.1 Introduction / 126
5.2 Bernoulli-Euler Beam Theory / 126
5.2.1 Unidirectional Bending on Beams with
a Symmetric Section / 126
5.2.2 Bidirectional Bending on Beams with
an Arbitrary Section / 132
5.3 Structural idealization / 137
5.4 Transverse Shear Stress due to Transverse Force in
Symmetric Sections / 146
5.4.1 Narrow Rectangular Cross-Section / 147
5.4.2 General Symmetric Sections / 148
5.4.3 Thin-Walled Sections / 150
5.34.4 Shear Deformation in Thin-Walled Sections / 151
5.5 Timoshenko Beam Theory / 154
5.6 Saing-Venant's Principle / 158
5.7 Shear Lag / 162
Problems / 165
6 Flexural Shear Flow in Thin-Walled Sections 171
6.1 Introduction / 171
6.2 Flexural Shear Flow in Open Thin-Walled Sections / 171
6.2.1 Symmetric Thin-Walled Sections / 172
6.2.2 Unsymmetric Thin-Walled Sections / 176
6.2.3 Multiple Shear Flow Junctions / 178
6.2.4 Selection of Shear Flow Contour / 179
6.3 Shear Center in Open Sections / 180
6.4 Closed Thin-Walled Sections and Combined Flexural and
Torsional Shear Flow / 186
6.4.1 Shear Center / 187
6.4.2 Statically Determinate Shear Flow / 191
6.5 Closed Multicell Sections / 194
Problems / 198
7 Failure Criteria for Isotropic Materials 205
7.1 Introduction / 205
7.2 Strength Criteria for Brittle Materials / 205
7.2.1 Maximum Principal Stress Criterion / 205
7.2.2 Coulomb-Mohr Criterion / 206
7.3 Yield Criteria for Ductile Materials / 208
7.3.1 Maximum Shear Stress Criterion (Tresca Yield
Criterion) in Plane Stress / 208
7.3.2 Maximum Distortion Energy Criterion (von Mises
Yield Criterion) / 210
7.4 Fracture Mechanics / 215
7.4.1 Stress Concentration / 215
7.4.2 Concept of Cracks and Strain Energy Release Rate / 216
7.4.3 Fracture Criterion / 218
7.5 Stress Intensity Factor / 223
7.5.1 Symmetric Loading (Mode I Fracture) / 223
7.5.2 Antisymmetric Loading (Mode II Fracture) / 225
7.5.3 Relation between K and G / 227
7.5.4 Mixed Mode Fracture / 231
7.6 Effect of Crack Tip Plasticity / 232
7.7 Fatigue Failure / 235
7.7.1 Constant Stress Amplitude / 235
7.7.2 S-N Curves / 235
7.7.3 Variable Amplitude Loading / 236
7.8 Fatigue Crack Growth / 236
Problems / 239
8 Elastic Buckling 244
8.1 Introduction
8.2 Eccentrically Loaded Beam-Column / 244
8.3 Elastic Buckling of Straight Bars / 245
8.3.1 Pinned-Pinned Bar / 247
8.3.2 Clamped-Free Bar / 250
8.3.3 Clamped-Pinned Bar / 251
8.3.4 Clamped-Clamped Bar / 252
8.3.5 Effective Length of Buckling / 253
8.4 Initial Imperfection / 254
8.5 Postbuckling Behavior / 256
8.6 Bar of Unsymmetric Section / 262
8.7 Torsional-Flexural Buckling of Thin-Walled Bars / 265
8.7.1 Nonuniform Torsion / 265
8.7.2 Torsional Buckling of Doubly Symmetric Section / 267
8.7.3 Torsional-Flexural Buckling / 269
8.8 Elastic Buckling of Flat Plates / 275
8.8.1 Governing Equation for Flat Plates / 273
8.8.2 Cylindrical Bending / 275
8.8.3 Buckling of Rectangular Plates / 276
8.8.4 Buckling under Shearing Stresses / 279
8.9 Local Buckling of Open Sections / 280
Problems / 282
9 Analysis of Composite Laminates 287
9.1 Plane Stress Equations for Composite Lamina / 287
9.2 Off-Axis Loading / 293
9.3 Notation for Stacking Sequence in Laminates / 295
9.4 Symmetric Laminate under In-Plane Loading / 296
9.5 Effective Moduli for Symmetric Laminates / 299
9.6 Laminar Stresses / 303
9.7 [+/-45 Degrees] Laminate / 305
Problems / 306
Index 308