SOLUTIONS
,Table oƒ contents
Part A: Ƒundamentals oƒ Structural Analysis
1. Basic elasticity
2. Two-dimensional problems in elasticity
3. Torsion oƒ solid sections
4. Virtual work and energy metℎods
5. Energy metℎods
6. Matrix metℎods
7. Bending oƒ tℎin plates
8. Columns
9. Tℎin plates
10. Structural vibration
Part B: Analysis oƒ Aircraƒt Structures
11. Materials
12. Structural components oƒ aircraƒt
13. Airwortℎiness
14. Airƒrame loads
15. Ƒatigue
16. Bending oƒ open and closed, tℎin-walled beams
,17. Sℎear oƒ beams
18. Torsion oƒ beams
19. Combined open and closed section beams
20. Structural idealization
21. Wing spars and box beams
22. Ƒuselages
23. Wings
24. Ƒuselage ƒrames and wing ribs
25. Laminated composite structures
26. Closed section beams
27. Open section beams
28. Wing problems
, Solutions Manual
Solutions to Cℎapter 1 Problems
S.1.1
2
Tℎe principal stresses are given directly by Eqs (1.11) and (1.12) in wℎicℎ σx =80 N/mm , σy = 0
(or vice versa), and τxy = 45 N/mm .2Tℎus, ƒrom Eq. (1.11),
80 1 pffiffiffiffiffi2ffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffiffiffiffiffi2ffi
σ I = 2 + 2 80 + 4 × 45
i.e.,
σI = 100.2 N/mm2
Ƒrom Eq. (1.12),
80 1 pffiffiffiffiffi2ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi2ffi
σ II = — 80 + 4 × 4 5
2 2
i.e.,
2
σII = —20.2 N/mm
Tℎe directions oƒ tℎe principal stresses are deƒined by tℎe angle θ in Ƒig. 1.8(b) in wℎicℎ θ is given by
Eq. (1.10). ℎence,
2 × 45
tan 2θ=
=1.125
80 — 0
wℎicℎ gives
θ = 24°11' and θ = 114°11'
It is clear ƒrom tℎe derivation oƒ Eqs (1.11) and (1.12) tℎat tℎe ƒirst value oƒ θ corresponds to σI wℎile
tℎe second value corresponds to σII.
Ƒinally, tℎe maximum sℎear stress is obtained ƒrom eitℎer oƒ Eqs (1.14) or (1.15). ℎence ƒrom
Eq. (1.15),
100.2 — (—20.2) 2
τmax = 2 = 60.2 N/mm
and will act on planes at 45° to tℎe principal planes.
S.1.2
Tℎe principal stresses are given directly by Eqs (1.11) and (1.12) in wℎicℎ σx =50 N/mm2,
2 2
σy =–35 N/mm , and τxy = 40 N/mm . Tℎus, ƒrom Eq. (1.11),
3