Mechanics of Aircraft Structures

Chapter 1: Characteristics of Aircraft Structures and Materials

• • 1.1 Introduction
• • 1.2 Types of Aircraft Structures
• • 1.2.1 Fixed-Wing Aircraft
• • 1.2.2 Rotorcraft
• • 1.2.3 Lighter-than-Air Vehicles
• • 1.2.4 Drones
• • 1.3 Basic Structural Elements in Aircraft Structure
• • 1.3.1 Fuselage
• • 1.3.2 Wing
• • 1.3.3 Landing Gear
• • 1.3.4 Control Surfaces
• • 1.4 Aircraft Materials
• • 1.4.1 Steel Alloys
• • 1.4.2 Aluminum Alloys
• • 1.4.3 Titanium Alloys
• • 1.4.4 Fiber-Reinforced Composites
• • Problems

Chapter 2: Loads on Aircraft Structures

• • 2.1 Introduction
• • 2.2 Basic Structural Elements
• • 2.2.1 Axial Member
• • 2.2.2 Shear Panel
• • 2.2.3 Bending Member (Beam)
• • 2.2.4 Torsion Member
• • 2.3 Wing and Fuselage
• • 2.3.1 Load Transfer
• • 2.3.2 Wing Structure
• • 2.3.3 Fuselage
• • Problems

Chapter 3: Introduction to Elasticity

• • 3.1 Introduction
• • 3.2 Concept of Displacement
• • 3.3 Strain
• • 3.3.1 Rigid Body Motion
• • 3.4 Stress
• • 3.5 Equations of Equilibrium in a Uniform Stress Field
• • 3.6 Equations of Equilibrium in a Nonuniform Stress Field
• • 3.7 Stress Vector and Stress Components Relations
• • 3.8 Principal Stress
• • 3.9 Shear Stress
• • 3.10 Stress Transformation
• • 3.11 Linear Stress–Strain Relations
• • 3.11.1 Strains Induced by Normal Stress
• • 3.11.2 Strains Induced by Shear Stress
• • 3.11.3 Three-Dimensional Stress–Strain Relations
• • 3.11.3.1 Orthotropic Materials
• • 3.11.3.2 Isotropic Materials
• • 3.12 Plane Elasticity
• • 3.12.1 Stress–Strain Relations for Plane Isotropic Solids
• • 3.12.1.1 Plane Strain
• • 3.12.1.2 Plane Stress
• • 3.12.2 Stress–Strain Relations for Orthotropic Solids in Plane Stress
• • 3.12.3 Governing Equations
• • 3.12.3.1 Equilibrium Equations
• • 3.12.3.2 Boundary Conditions
• • 3.12.3.3 Compatibility Equation
• • 3.12.4 Solution by Airy Stress Function for Plane Isotropic Solids
• • 3.12.5 Plane Elasticity Solutions in Polar Coordinate System
• • 3.12.5.1 Strain–Displacement Relations
• • 3.12.5.2 Stresses in Polar Coordinates and Equilibrium Equations
• • 3.12.5.3 Stress–Strain Relations
• • 3.12.5.4 Stress Function Formulations
• • 3.13 Formulations Beyond 2-D Plane Elasticity
• • Problems
• • References

Chapter 4: Torsion

• • 4.1 Introduction
• • 4.2 Torsion of Uniform Bars With Arbitrary Cross-Section
• • 4.2.1 Governing Equations
• • 4.2.2 Boundary Conditions
• • 4.2.3 Torque–Stress Relations
• • 4.2.4 Warping Displacement
• • 4.2.5 Torsion Constant
• • 4.3 Bars With Circular Cross-Sections
• • 4.3.1 Elasticity Approach Using Prandtl Stress Function
• • 4.3.2 Mechanics of Solid Approach
• • 4.4 Bars With Narrow Rectangular Cross-Sections
• • 4.5 Closed Single-Cell Thin-Walled Sections
• • 4.5.1 The s–n Coordinate System
• • 4.5.2 Prandtl Stress Function
• • 4.5.3 Shear Flow q
• • 4.5.4 Shear Flow–Torque Relation
• • 4.5.5 Twist Angle
• • 4.5.5.1 Method 1
• • 4.5.5.2 Method 2 for Constant Shear Flow
• • 4.5.6 Torsion Constant J
• • 4.6 Multicell Thin-Walled Sections
• • 4.7 Warping in Open Thin-Walled Sections
• • 4.8 Warping in Closed Thin-Walled Sections
• • 4.9 Effect of End Constraints
• • Problems
• • References

Chapter 5: Bending and Flexural Shear

• • 5.1 Introduction
• • 5.2 Bernoulli–Euler Beam Theory
• • 5.2.1 Unidirectional Bending on Beams with a Symmetric Section
• • 5.2.2 Bidirectional Bending on Beams with an Arbitrary Section
• • 5.3 Structural Idealization
• • 5.4 Transverse Shear Stress Due to Transverse Force in Symmetric Sections
• • 5.4.1 Narrow Rectangular Cross-Section
• • 5.4.2 General Symmetric Sections
• • 5.4.3 Thin-Walled Sections
• • 5.4.4 Shear Deformation in Thin-Walled Sections
• • 5.5 Timoshenko Beam Theory
• • 5.6 Saint-Venant’s principle
• • 5.7 Shear Lag
• • Problems
• • Reference

Chapter 6: Flexural Shear Flow in Thin-Walled Sections

• • 6.1 Introduction
• • 6.2 Flexural Shear Flow in Open Thin-Walled Sections
• • 6.2.1 Symmetric Thin-Walled Sections
• • 6.2.1.1 Stringer–Web Sections
• • 6.2.2 Unsymmetric Thin-Walled Sections
• • 6.2.3 Multiple Shear Flow Junctions
• • 6.2.4 Selection of Shear Flow Contour
• • 6.3 Shear Center in Open Sections
• • 6.4 Closed Thin-Walled Sections and Combined Flexural and Torsional Shear Flow
• • 6.4.1 Shear Center
• • 6.4.2 Statically Determinate Shear Flow
• • 6.5 Closed Multicell Sections
• • Problems

Chapter 7: Failure Criteria for Isotropic Materials

• • 7.1 Introduction
• • 7.2 Strength Criteria for Brittle Materials
• • 7.2.1 Maximum Principal Stress Criterion
• • 7.2.2 Coulomb–Mohr Criterion
• • 7.3 Yield Criteria for Ductile Materials
• • 7.3.1 Maximum Shear Stress Criterion (Tresca Yield Criterion) in Plane Stress
• • 7.3.2 Maximum Distortion Energy Criterion (von Mises Yield Criterion)
• • 7.4 Fracture Mechanics
• • 7.4.1 Stress Concentration
• • 7.4.2 Concept of Cracks and Strain Energy Release Rate
• • 7.4.3 Fracture Criterion
• • 7.4.3.1 Strain Energy in Structural Members
• • 7.4.3.2 Axial Element
• • 7.4.3.3 Beam Element
• • 7.4.3.4 Torsion Member
• • 7.5 Stress Intensity Factor
• • 7.5.1 Symmetric Loading (Mode I Fracture)
• • 7.5.2 Antisymmetric Loading (Mode II Fracture)
• • 7.5.3 Relation between K and G
• • 7.5.4 Mixed Mode Fracture
• • 7.6 Effect of Crack Tip Plasticity
• • 7.7 Fatigue Failure
• • 7.7.1 Constant Stress Amplitude
• • 7.7.2 S–N Curves
• • 7.7.3 Variable Amplitude Loading
• • 7.8 Fatigue Crack Growth
• • Problems
• • References

Chapter 8: Elastic Buckling

• • 8.1 Introduction
• • 8.2 Eccentrically Loaded Beam-Column
• • 8.3 Elastic Buckling of Straight Bars
• • 8.3.1 Pinned–Pinned Bar
• • 8.3.2 Clamped–Free Bar
• • 8.3.3 Clamped–Pinned Bar
• • 8.3.4 Clamped–Clamped Bar
• • 8.3.5 Effective Length of Buckling
• • 8.4 Initial Imperfection
• • 8.5 Postbuckling Behavior
• • 8.6 Bar of Unsymmetric Section
• • 8.7 Torsional–Flexural Buckling of Thin-Walled Bars
• • 8.7.1 Nonuniform Torsion
• • 8.7.2 Torsional Buckling of Doubly Symmetric Section
• • 8.7.3 Torsional–Flexural Buckling
• • 8.8 Elastic Buckling of Flat Plates
• • 8.8.1 Governing Equation for Flat Plates
• • 8.8.1.1 Boundary Conditions
• • 8.8.1.2 Clamped Edge
• • 8.8.1.3 Simply Supported Edge
• • 8.8.1.4 Free Edge
• • 8.8.2 Cylindrical Bending
• • 8.8.3 Buckling of Rectangular Plates
• • 8.8.3.1 Simply Supported Edges
• • 8.8.3.2 Other Boundary Conditions
• • 8.8.4 Buckling Under Shearing Stresses
• • 8.9 Local Buckling of Open Sections
• • Problems

Chapter 9: Analysis of Composite Laminates

• • 9.1 Plane Stress Equations for Composite Lamina
• • 9.2 Off-Axis Loading
• • 9.3 Notation for Stacking Sequence in Laminates
• • 9.3.1 Symmetry
• • 9.3.2 Repetition
• • 9.4 Symmetric Laminate Under In-Plane Loading
• • 9.5 Effective Moduli for Symmetric Laminates
• • 9.5.1 Quasi-Isotropic Laminate
• • 9.6 Laminar Stresses
• • 9.7 [±45 ] Laminate
• • 9.7.1 Determination of G 12 Using ±45 Laminates
• • Problems