Mechanics of Aircraft Structures

by C. T. Sun, Ashfaq Adnan

Overview

MECHANICS OF AIRCRAFT STRUCTURES

Explore the most up-to-date overview of the foundations of aircraft structures combined with a review of new aircraft materials

The newly revised Third Edition of Mechanics of Aircraft Structures delivers a combination of the fundamentals of aircraft structure with an overview of new materials in the industry and a collection of rigorous analysis tools into a single one-stop resource. Perfect for a one-semester introductory course in structural mechanics and aerospace engineering, the distinguished authors have created a textbook that is also ideal for mechanical or aerospace engineers who wish to stay updated on recent advances in the industry.

The new edition contains new problems and worked examples in each chapter and improves student accessibility. A new chapter on aircraft loads and new material on elasticity and structural idealization form part of the expanded content in the book. Readers will also benefit from the inclusion of:

• A thorough introduction to the characteristics of aircraft structures and materials, including the different types of aircraft structures and their basic structural elements
• An exploration of load on aircraft structures, including loads on wing, fuselage, landing gear, and stabilizer structures
• An examination of the concept of elasticity, including the concepts of displacement, strain, and stress, and the equations of equilibrium in a nonuniform stress field
• A treatment of the concept of torsion

Perfect for senior undergraduate and graduate students in aerospace engineering, Mechanics of Aircraft Structures will also earn a place in the libraries of aerospace engineers seeking a one-stop reference to solidify their understanding of the fundamentals of aircraft structures and discover an overview of new materials in the field.

Product Details

ISBN-13:	9781119583912
Publisher:	Wiley
Publication date:	09/28/2021
Edition description:	3rd ed.
Pages:	320
Product dimensions:	7.10(w) x 10.10(h) x 1.00(d)

About the Author

C. T. Sun, PhD, is Neil A. Armstrong Distinguished Professor Emeritus of Aeronautics and Astronautics at Purdue University. Dr. Sun was the inaugural recipient of the AIAA-ASC James H. Starnes Award and the 2007 ASME Warner T. Koiter Medal.

Ashfaq Adnan, PhD, is Professor in the Mechanical and Aerospace Engineering Department at the University of Texas at Arlington and a Fellow of ASME. His research focus is on deformation, damage, and failure of biological, bioinspired, and engineered materials at multiple length scales.

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Table of Contents

Preface to the Third Edition xiii

Preface to the Second Edition xv

Preface to the First Edition xvii

About the Companion Website xix

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 2

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 4

1.3.4 Control Surfaces 4

1.4 Aircraft Materials 5

1.4.1 Steel Alloys 5

1.4.2 Aluminum Alloys 6

1.4.3 Titanium Alloys 6

1.4.4 Fiber-Reinforced Composites 6

Problems 7

2 Loads on Aircraft Structures 9

2.1 Introduction 9

2.2 Basic Structural Elements 9

2.2.1 Axial Member 9

2.2.2 Shear Panel 11

2.2.3 Bending Member (Beam) 12

2.2.4 Torsion Member 13

2.3 Wing and Fuselage 15

2.3.1 Load Transfer 15

2.3.2 Wing Structure 16

2.3.3 Fuselage 17

Problems 20

3 Introduction to Elasticity 23

3.1 Introduction 23

3.2 Concept of Displacement 24

3.3 Strain 26

3.3.1 Rigid Body Motion 28

3.4 Stress 30

3.5 Equations of Equilibrium in a Uniform Stress Field 31

3.6 Equations of Equilibrium in a Nonuniform Stress Field 33

3.7 Stress Vector and Stress Components Relations 35

3.8 Principal Stress 37

3.9 Shear Stress 40

3.10 Stress Transformation 41

3.11 Linear Stress-Strain Relations 44

3.11.1 Strains Induced by Normal Stress 45

3.11.2 Strains Induced by Shear Stress 47

3.11.3 Three-Dimensional Stress-Strain Relations 47

3.11.3.1 Orthotopic Materials 49

3.11.3.2 Isotropic Materials 50

3.12 Plane Elasticity 51

3.12.1 Stress-Strain Relations for Plane Isotropic Solids 52

3.12.1.1 Plane Strain 52

3.12.1.2 Plane Stress 53

3.12.2 Stress-Strain Relations for Orthotropic Solids in Plane Stress 54

3.12.3 Governing Equations 55

3.12.3.1 Equilibrium Equations 55

3.12.3.2 Boundary Conditions 55

3.12.3.3 Compatibility Equation 56

3.12.4 Solution by Airy Stress Function for Plane Isotropic Solids 57

3.12.5 Plane Elasticity Solutions in Polar Coordinate System 59

3.12.5.1 Strain-Displacement Relations 59

3.12.5.2 Stresses in Polar Coordinates and Equilibrium Equations 60

3.12.5.3 Stress-Strain Relations 61

3.12.5.4 Stress Function Formulations 61

3.13 Formulations Beyond 2-D Plane Elasticity 62

Problems 64

References 71

4 Torsion 73

4.1 Introduction 73

4.2 Torsion of Uniform Bars With Arbitrary Cross-Section 73

4.2.1 Governing Equations 74

4.2.2 Boundary Conditions 76

4.2.3 Torque-Stress Relations 77

4.2.4 Warping Displacement 78

4.2.5 Torsion Constant 79

4.3 Bars With Circular Cross-Sections 79

4.3.1 Elasticity Approach Using Prandtl Stress Function 79

4.3.2 Mechanics of Solid Approach 82

4.4 Bars With Narrow Rectangular Cross-Sections 85

4.5 Closed Single-Cell Thin-Walled Sections 88

4.5.1 The s-n Coordinate System 88

4.5.2 Prandtl Stress Function 90

4.5.3 Shear Flow q 91

4.5.4 Shear Flow-Torque Relation 91

4.5.5 Twist Angle 93

4.5.5.1 Method 1 93

4.5.5.2 Method 2 for Constant Shear Flow 94

4.5.6 Torsion Constant J 95

4.6 Multicell Thin-Walled Sections 98

4.7 Warping in Open Thin-Walled Sections 102

4.8 Warping in Closed Thin-Walled Sections 106

4.9 Effect of End Constraints 108

Problems 114

References 119

5 Bending and Flexural Shear 121

5.1 Introduction 121

5.2 Bernoulli-Euler Beam Theory 121

5.2.1 Unidirectional Bending on Beams with a Symmetric Section 121

5.2.2 Bidirectional Bending on Beams with an Arbitrary Section 127

5.3 Structural Idealization 131

5.4 Transverse Shear Stress Due to Transverse Force in Symmetric Sections 139

5.4.1 Narrow Rectangular Cross-Section 139

5.4.2 General Symmetric Sections 141

5.4.3 Thin-Walled Sections 142

5.4.4 Shear Deformation in Thin-Walled Sections 143

5.5 Timoshenko Beam Theory 146

5.6 Saint-Venant's principle 149

5.7 Shear Lag 152

Problems 155

Reference 160

6 Flexural Shear Flow in Thin-Walled Sections 161

6.1 Introduction 161

6.2 Flexural Shear Flow in Open Thin-Walled Sections 161

6.2.1 Symmetric Thin-Walled Sections 161

6.2.1.1 Stringer-Web Sections 164

6.2.2 Unsymmetric Thin-Walled Sections 166

6.2.3 Multiple Shear Flow Junctions 168

6.2.4 Selection of Shear Flow Contour 169

6.3 Shear Center in Open Sections 169

6.4 Closed Thin-Walled Sections and Combined Flexural and Torsional Shear Flow 175

6.4.1 Shear Center 176

6.4.2 Statically Determinate Shear Flow 179

6.5 Closed Multicell Sections 182

Problems 186

7 Failure Criteria for Isotropic Materials 193

7.1 Introduction 193

7.2 Strength Criteria for Brittle Materials 193

7.2.1 Maximum Principal Stress Criterion 193

7.2.2 Coulomb-Mohr Criterion 194

7.3 Yield Criteria for Ductile Materials 196

7.3.1 Maximum Shear Stress Criterion (Tresca Yield Criterion) in Plane Stress 196

7.3.2 Maximum Distortion Energy Criterion (von Mises Yield Criterion) 197

7.4 Fracture Mechanics 203

7.4.1 Stress Concentration 203

7.4.2 Concept of Cracks and Strain Energy Release Rate 204

7.4.3 Fracture Criterion 205

7.4.3.1 Strain Energy in Structural Members 205

7.4.3.2 Axial Element 206

7.4.3.3 Beam Element 206

7.4.3.4 Torsion Member 206

7.5 Stress Intensity Factor 210

7.5.1 Symmetric Loading (Mode I Fracture) 210

7.5.2 Antisymmetric Loading (Mode II Fracture) 212

7.5.3 Relation between K and G 213

7.5.4 Mixed Mode Fracture 217

7.6 Effect of Crack Tip Plasticity 218

7.7 Fatigue Failure 220

7.7.1 Constant Stress Amplitude 220

7.7.2 S-N Curves 221

7.7.3 Variable Amplitude Loading 221

7.8 Fatigue Crack Growth 222

Problems 224

References 228

8 Elastic Buckling 229

8.1 Introduction 229

8.2 Eccentrically Loaded Beam-Column 229

8.3 Elastic Buckling of Straight Bars 230

8.3.1 Pinned-Pinned Bar 232

8.3.2 Clamped-Free Bar 235

8.3.3 Clamped-Pinned Bar 236

8.3.4 Clamped-Clamped Bar 237

8.3.5 Effective Length of Buckling 238

8.4 Initial Imperfection 239

8.5 Postbuckling Behavior 241

8.6 Bar of Unsymmetric Section 246

8.7 Torsional-Flexural Buckling of Thin-Walled Bars 248

8.7.1 Nonuniform Torsion 248

8.7.2 Torsional Buckling of Doubly Symmetric Section 249

8.7.3 Torsional-Flexural Buckling 252

8.8 Elastic Buckling of Flat Plates 256

8.8.1 Governing Equation for Flat Plates 256

8.8.1.1 Boundary Conditions 257

8.8.1.2 Clamped Edge 258

8.8.1.3 Simply Supported Edge 258

8.8.1.4 Free Edge 258

8.8.2 Cylindrical Bending 258

8.8.3 Buckling of Rectangular Plates 259

8.8.3.1 Simply Supported Edges 259

8.8.3.2 Other Boundary Conditions 262

8.8.4 Buckling Under Shearing Stresses 262

8.9 Local Buckling of Open Sections 263

Problems 265

9 Analysis of Composite Laminates 271

9.1 Plane Stress Equations for Composite Lamina 271

9.2 Off-Axis Loading 276

9.3 Notation for Stacking Sequence in Laminates 278

9.3.1 Symmetry 279

9.3.2 Repetition 279

9.4 Symmetric Laminate Under In-Plane Loading 279

9.5 Effective Moduli for Symmetric laminates 281

9.5.1 Quasi-Isotropic Laminate 283

9.6 Laminar Stresses 284

9.7 [±45°] Laminate 286

9.7.1 Determination of G₁₂ Using ±45° Laminates 287

Problems 288

Index 291