Aircraft Structures for Engineering Students

Part A Fundamentals of Structural Analysis A I Elasticity 1. Basic elasticity 1.1 Stress 1.2 Notation for forces and stress 1.3 Equations of equilibrium 1.4 Plane stress 1.5 Boundary conditions 1.6 Determination of stresses on inclined planes 1.7 Principal Stresses 1.8 Mohr s circle of stress 1.9 Strain 1.10 compatibility equations 1.11 Plane strain 1.12 Determination of strains on inclined planes 1.13 Principal strains 1.14 Mohr s circle of strain 1.15 Stress-strain relationships 1.16 Experimental measurement of surface strains2. Two-dimensional problems in elasticity 2.1 Two-dimensional problems 2.2 Stress functions 2.3 Inverse and semi-inverse methods 2.4 St. Venant s principle 2.5 Displacements 2.6 Bending of an end-loaded cantilever 3. Torsion of solid sections 3.1 Prandtl stress function solution 3.2 St. Venant warping function solution 3.3 The membrane analogy 3.4 Torsion of a narrow rectangular strip A II Virtual Work, Energy and Matrix Methods 4. Virtual work 4.1 Work 4.2 Principle of virtual work 4.2.1 For a particle 4.2.2 For a rigid body 4.2.3 Virtual work in a deformable body 4.2.4 Work done by internal force systems 4.2.5 Virtual work due to external force systems 4.3.6 Use of virtual force systems 4.3 Applications of the principle of virtual work 5. Energy methods 5.1 Strain energy and complementary energy 5.2 The principle of the stationary value of the total complementary energy 5.3 Application to deflection problems 5.4 Application to the solution of statically indeterminate systems 5.5 Unit load method 5.6 Flexibility method 5.6.1 Self Straining method 5.7 Total potential energy 5.8 the principle of the stationary value of the total potential energy 5.9 Principle of superposition 5.10 Reciprocal theorems 5.11 Temperature effects 6. Matrix methods 6.1 Notation6.2 Stiffness matrix for an elastic spring6.3 Stiffness matrix for two elastic springs in line6.4 Matrix analysis of pin-jointed frameworks6.5 Application to statically indeterminate frameworks6.6 Matrix analysis of space frames6.7 Stiffness matrix for a uniform beam6.8 Finite element method for continuum structures 6.8.1 Stiffness matrix for a beam-element 6.8.2 Stiffness matrix for a triangular finite element 6.8.3 Stiffness matrix for a quadrilateral element A III Thin Plate Theory 7. Bending of thin plates 7.1 Pure Bending of thin plates 7.2 Plates subjected to bending and twitsting 7.3 Plates subjected to a distributed transverse load 7.3.1 The simply supported edge 7.3.2 The built-in edge 7.3.3 The free edge 7.4 Combined bending and in-plane loading of a thin rectangular plate 7.5 Bending of thin plates having a small initial curvature 7.6 Energy method for the bending of thin plates 7.6.1 Strain energy produced by bending and twisting 7.6.2 Potential energy of a transverse load 7.6.3 Potential energy of in-plane loads A IV Structural Instability 8. Columns 8.1 Euler buckling of columns 8.2 Inelastic buckling 8.3 Effect of initial imperfections 8.4 Stability of beams under transverse and axial loads 8.5 Energy method for the calculation of buckling loads in columns 9. Thin plates 9.1 Buckling of thin plates 9.2 Inelastic buckling of plates 9.3 Experimental determination of critical load for a flat plate 9.4 Local instability 9.5 Instability of stiffened panels 9.6 Failure stress in plates and stiffened panels 9.7 Tension field beams 9.7.1 Complete diagonal 9.7.2 Incomplete diagonal tension 9.7.3 Post buckling behaviour 10. Structural Vibration 10.1 Oscillation of mass/spring systems 10.2 Oscillation of beams 10.3 Approximate methods for determining natural frequencies Part B Analysis of Aircraft Structures B I Principles of Stressed Skin Construction11. Materials 11.1 Aluminium alloys 11.2 Steel 11.3 Titanium 11.4 Plastics 11.5 Glass 11.6 Composites 11.7 Properties of materials12. Structural components of aircraft 12.1 Loads on components 12.2 Function of components 12.3 Fabrication of components 12.4 Connections Structural Vibration BII Airworthiness and Airframe Loads 13. Airworthiness 13.1 Factors of safety - flight envelope 13.2 Load factor determination 13.2.1 Limit load 13.2.2 Structural deterioration and uncertainties in design 13.2.3 Variation in structural strength 13.2.4 Fatigue 14. Airframe loads 14.1 Inertia loads 14.2 Symmetric manoeuvre loads 14.2.1 Level flight 14.2.2 General case 14.3 Normal acceleration associated with various types of manoeuvre 14.3.1 Steady pull-out 14.3.2 Correctly banked turn 14.4 Gust loads 14.4.1 Sharp-edged gust 14.4.2 The "graded" gust 14.4.3 Gust envelope 15. Fatigue 15.1 Safe life and fail safe structures 15.2 Designing against fatigue 15.3 Fatigue strength of components 15.4 Prediction of aircraft fatigue life 15.5 Creep 15.6 Crack propagation B III Bending, Shear and Torsion of Thin-Walled Beams 16. Bending of open and closed, Thin-Walled Beams 16.1 Symmetrical Bending16.1.1 Assumptions 16.1.2 Direct Stress Distribution 16.1.3 Anticlastic Bending 16.2 Unsymmetrical Bending 16.2.1 Sign Conventions and notation 16.2.2 Resolution of bending moments 16.2.3 Direct Stress distribution due to bending 16.2.4 Position of the neutral axis 16.2.5Load intensity, shear force and bending moment relationships, general case 16.3 Deflections due to bending 16.4 Calculation of Section Properties 16.4.1 Parallel Axes Theorem 16.4.2 Theorem of Perpendicular Axes 16.4.3 Second Moments of Area of Standard Sections 16.5 Application of bending theory17. Shear of beams 17.1 General stress, strain and displacement relationships 17.2 Open section beams 17.2.1 Shear centre 17.3 Closed section beams 17.3.1 Twist and warping 17.3.2 Shear centre18. Torsion of beams 18.1 Closed section beams 18.1.1 Displacements associated with the Bredt-Batho shear flow 18.1.2 Condition for zero warping 18.2 Torsion of open section beams 18.2.1 Warping of cross-section19. Combined open and closed section beams 19.1 Bending 19.2 Shear 19.3 Torsion 20. Structural Idealisation 20.1 Principle 20.2 Idealisation of a panel 20.3 Effect of idealisation on the analysis of open and closed section beams 20.3.1 Bending of open and closed section beams 20.3.2 Shear of open section beams 20.3.3 Shear of closed section beams 20.3.4 Alternative method for the calculation of shear flow distribution 20.3.5 Torsion of open and closed section beams B IV Stress Analysis of Aircraft Components 21. Wing spars and box beams 21.1 Tapered wing spar 21.2 Open and closed section box beams 21.3 Beams having variable stringer areas 22. Fuselages 22.1 Bending 22.2 Shear 22.3 Torsion 22.4 Effect of cut-outs 23. Wings 23.1 Three-boom shell 23.2 Bending 23.3 Torsion 23.4 Shear 23.5 Shear centre 23.6 Tapered wings 23.7 Deflections 23.8 Effect of cut-outs 24. Fuselage frames and wing ribs 24.1 Principles of Stiffener/web construction 24.2 Fuselage frames 24.3 Wing ribs 25. Laminated composite structures 25.1 Elastic constants of simple lamina 2.5.2 Stress-strain relationships for an orthotropic ply (macro-approach) 25.2.1 Specially orthotropic ply 25.2.2 Generally orthotropic ply 25.3 Thin-walled composite beams 25.3.1 Axial load 25.3.2 Bending 25.3.3 Shear 25.3.4 TorsionBV Structural and Loading Discontinuities 26. Closed section beams 26.1 General aspects 26.2 Shear distribution at a built-in end 26.3 Torsion of a rectangular section beam 26.4 Shear lag 27. Open section beams 27.1 I-section beam subjected to torsion 27.2 Arbitrary section beam subjected to torsion 27.3 Distributed torque loading 27.4 General system of loading 27.5 Moment couple (bimoment) 27.5.1 Shear flow due to MTB VI Introduction to Aeroelasticity 28. Wing problems 28.1 Types of problem 28.2 Load distribution and divergence 28.2.1 Wing torsional divergence (two-dimensional) 28.2.1 Wing torsional divergence (finite wing) 28.2.3 Swept wing divergence 28.3 Control effectiveness and reversal 28.3.1 Aileron effectiveness and reversal (two-dimensional) 28.3.2 Aileron effectiveness and reversal (finite wing) 28.4 Introduction to Flutter 28.4.1 Coupling 28.4.2 Critical flutter speed 28.4.3 Prevention of flutter 28.4.4 Experimental determination of flutter speed. 28.4.5 Control surface flutter APPENDIX Case Study : Design of an Aircraft Fuselage Requirement: The aircraft A1. SpecificationA2. DataA3. Initial calculationsA4. Balancing out calculationsA5. Fuselage loadsA6. Fuselage design calculations