Aircraft Structures B H. for engineering students. T. H. G. Megson ELSEVIER SAN FRANCISCO SINGAPORE SYDNEY TOKYO

Transcription

1 Aircraft Structures for engineering students Fifth Edition T. H. G. Megson Sag- ELSEVIER AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK OXFORD PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO Butterworth-Heinemann is an imprint of Elsevier B H

2 Preface xv PART A FUNDAMENTALS OF STRUCTURAL ANALYSIS Section A1 Elasticity 3 CHAPTER 1 Basic elasticity Stress Notation for forces and stresses Equations of equilibrium Plane stress Boundary conditions Determination of stresses on inclined planes Principal stresses Mohr's circle of stress Strain Compatibility equations Plane strain Determination of strains on inclined planes Principal strains Mohr's circle of strain Stress-strain relationships Experimental measurement of surface strains 37 References CHAPTER 2 Two-dimensional problems in elasticity Two-dimensional problems Stress functions Inverse and semi-inverse methods St. Venant's principle Displacements Bending of an end-loaded cantilever 58 Reference CHAPTER 3 Torsion of solid sections Prandtl stress function solution St. Venant warping function solution 81 vii

3 viii 3.3 The membrane analogy Torsion of a narrow rectangular strip 84 References Section A2 Virtual work, energy, and matrix methods 89 CHAPTER 4 Virtual work and energy methods Work Principle of virtual work Applications of the principle of virtual work 106 Reference CHAPTER 5 Energy methods Strain energy and complementary energy Principle of the stationary value of the total complementary energy Application to deflection problems Application to the solution of statically indeterminate systems Unit load method Flexibility method Total potential energy Principle of the stationary value of the total potential energy Principle of superposition Reciprocal theorem Temperature effects 168 References CHAPTER 6 Matrix methods Notation Stiffness matrix for an elastic spring Stiffness matrix for two elastic springs in line Matrix analysis of pin-jointed frameworks Application to statically indeterminate frameworks Matrix analysis of space frames Stiffness matrix for a uniform beam Finite element method for continuum structures 205 References 223 Further reading

4 ix Section A3 Thin plate theory 231 CHAPTER 7 Bending of thin plates Pure bending of thin plates Plates subjected to bending and twisting Plates subjected to a distributed transverse load Combined bending and in-plane loading of a thin rectangular plate Bending of thin plates having a small initial curvature Energy method for the bending of thin plates 255 Further reading Section A4 Structural instability 267 CHAPTER 8 Columns Euler buckling of columns Inelastic buckling Effect of initial imperfections Stability of beams under transverse and axial loads Energy method for the calculation of buckling loads in columns Flexural-torsional buckling of thin-walled columns 289 References CHAPTER 9 Thin plates Buckling of thin plates Inelastic buckling of plates Experimental determination of the critical load for a fiat plate Local instability Instability of stiffened panels Failure stress in plates and stiffened panels Tension field beams 322 References Section A5 Vibration of structures 343 CHAPTER 10 Structural vibration Oscillation of mass-spring systems Oscillation of beams Approximate methods for determining natural frequencies

5 x PART B ANALYSIS OF AIRCRAFT STRUCTURES Section B1 Principles of stressed skin construction 369 CHAPTER 11 Materials Aluminum alloys Steel Titanium Plastics Glass Composite materials Properties of materials CHAPTER 12 Structural components of aircraft 395 " 12.1 Loads on structural components Function of structural components Fabrication of structural components Connections 407 Reference Section B2 Airworthiness and airframe loads 417 CHAPTER 13 Airworthiness Factors of the safety-flight envelope Load factor determination 421 Reference 424 CHAPTER 14 Airframe loads Aircraft inertia loads Symmetric maneuver loads Normal accelerations associated with various types of maneuver Gust loads 440 References CHAPTER 15 Fatigue Safe life and fail-safe structures Designing against fatigue Fatigue strength of components Prediction of aircraft fatigue life 463

6 15.5 Crack propagation 469 References 476 Further reading Section B3 Bending, shear and torsion of thin-walled beams 479 CHAPTER 16 Bending of open and closed, thin-walled beams Symmetrical bending Unsymmetrical bending Deflections due to bending Calculation of section properties Applicability of bending theoiy Temperature effects 521 Reference CHAPTER 17 Shear of beams General stress, strain, and displacement relationships for open and single-cell closed section thin-walled beams Shear of open section beams Shear of closed section beams 548 Reference CHAPTER 18 Torsion of beams Torsion of closed section beams Torsion of open section beams CHAPTER 19 Combined open and closed section beams Bending Shear Torsion CHAPTER 20 Structural idealization Principle Idealization of a panel Effect of idealization on the analysis of open and closed section beams Deflection of open and closed section beams

7 xii Section B4 Stress analysis of aircraft components 627 CHAPTER 21 Wing spars and box beams 21.1 Tapered wing spar Open and closed section beams 21.3 Beams having variable stringer areas CHAPTER 22 Fuselages Bending Shear Torsion Cut-outs in fuselages CHAPTER 23 Wings Three-boom shell Bending Torsion Shear 23.5 Shear center Tapered wings 23.7 Deflections 23.8 Cut-outs in wings CHAPTER 24 Fuselage frames and wing ribs 24.1 Principles of stiffener/web construction 24.2 Fuselage frames 24.3 Wing ribs CHAPTER 25 Laminated composite structures 25.1 Elastic constants of a simple lamina 25.2 Stress-strain relationships for an orthotropic ply (macro approach) Thin-walled composite beams References Section B5 Structural and loading discontinuities 731 CHAPTER 26 Closed section beams General aspects 733

8 xiii 26.2 Shear stress distribution at a built-in end of a closed section beam Thin-walled rectangular section beam subjected to torsion Shear lag 748 Reference CHAPTER 27 Open section beams I-section beam subjected to torsion Torsion of an arbitrary section beam Distributed torque loading Extension of the theory to allow for general systems of loading Moment couple (bimoment) 790 References Section B6 Introduction to aeroelasticity 799 CHAPTER 28 Wing problems Types of problem Load distribution and divergence Control effectiveness and reversal Introduction to "flutter" 814 References Appendix: Design of a rear fuselage 825 Index 853