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AE 440 Structures Discipline Lecture 6

AE 440 Structures Discipline Lecture 6. Eric Loth For AE 440 A/C Lecture. Structures Responsibilities. Determine V-n relationships and establish a V-n diagram Establish and maintain load paths

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AE 440 Structures Discipline Lecture 6

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  1. AE 440Structures Discipline Lecture 6 Eric Loth For AE 440 A/C Lecture

  2. Structures Responsibilities • Determine V-n relationships and establish a V-n diagram • Establish and maintain load paths • Determine component materials (weights and dimensions to configuration) and consider environmental impact of acquisition, production and operations • Determine landing gear configuration • Carry out a detailed structural design of the wing box and wing attachment and structurally design landing gear (weights & dimensions to configuration) • Employ FEM Analysis

  3. Three Primary Structural Loads

  4. Typical Aircraft Loads

  5. Limit Load Factors

  6. V-n Diagram http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/MainFrame?OpenFrameSet

  7. Load Paths • How loads are transferred from one structural member to another • Wing skin—torsion and shear stress • Wing ribs—maintain shape and rigidity, transfer loads from skin to spars • Wing spars—bending moments • Fuselage—bulkheads, framers, stringers

  8. Lift Distribution

  9. Spanwise Load Distribution

  10. Typical Wing Box (AE 441)

  11. Major Fuselage Loads • Empennage loads due to trim, maneuvering, turbulence and gusts • Pressure loads due to cabin pressurization • Landing gear loads due to landing impact, taxiing and ground maneuvering • Loads induced by the propulsion installation when the latter is attached to the fuselage

  12. Fuselage Structure

  13. Structural Components • Spars • Ribs • Skin • Beam shear • Beam bending • Torsion Cessna Citation II

  14. Materials • Selection criteria • Strength • Stiffness • Density • Cost • Typical materials • Aluminum • Composites • Steel • Titanium • Mini-UAV materials • Plastic • Balsa • Fiber (cloth)

  15. Stress vs. Strain= Stiffness

  16. Landing Gear Loads • Vertical loads primarily caused by non-zero touchdown rates and taxiing over rough surfaces • Longitudinal loads primarily caused by braking loads and rolling friction loads • Lateral loads primarily caused by ‘crabbed landings,’ cross-wind taxiing and ground turning

  17. Common Landing Gear Configurations

  18. Samples of Structural Results from Previous CDRs

  19. V-n Diagram

  20. Spanwise Lift Distribution

  21. Spanwise Load Distribution

  22. Moment Distribution

  23. Structural Weight and Deflection

  24. Structural Configuration (441 level) I-beam gives good resistance to shear (web) and bending (caps)

  25. Structural Details (441 level)

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