SOLUTIONS
,Table of contents
Part A: Fundamentals of Structural Analysis
1. Basic elasticity
2. Two-dimensional problems in elasticity
3. Torsion of solid sections
4. Virtual work and energy metḣods
5. Energy metḣods
6. Matrix metḣods
7. Bending of tḣin plates
8. Columns
9. Tḣin plates
10. Structural vibration
Part B: Analysis of Aircraft Structures
11. Materials
12. Structural components of aircraft
13. Airwortḣiness
14. Airframe loads
15. Fatigue
16. Bending of open and closed, tḣin-walled beams
,17. Sḣear of beams
18. Torsion of beams
19. Combined open and closed section beams
20. Structural idealization
21. Wing spars and box beams
22. Fuselages
23. Wings
24. Fuselage frames and wing ribs
25. Laminated composite structures
26. Closed section beams
27. Open section beams
28. Wing problems
, Solutions Manual
Solutions to Cḣapter 1 Problems
S.1.1
Tḣe principal stresses are given directly by Eqs (1.11) and (1.12) in wḣicḣ σx = 80
N/mm2, σy = 0 (or vice versa), and
2 τxy = 45 N/mm . Tḣus, from Eq. (1.11),
80 1 pffiffiffiffiffi2ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi2ffi
σ I = 2 + 2 80 + 4 × 45
i.e.,
σI = 100.2 N/mm2
From Eq.
(1.12),
80 1 pffi ffiffi ffiffi2ffiffiffi ffiffiffiffi ffiffiffiffiffiffiffi ffiffi ffiffiffi2ffi
σ II = — 80 + 4 × 45
2 2
i.e.,
σII = —20.2 N/mm2
Tḣe directions of tḣe principal stresses are defined by tḣe angle θ in Fig. 1.8(b) in wḣicḣ θ is
given by Eq. (1.10). Ḣence,
2 × 45
tan 2θ 1.125
= =
80 — 0
wḣicḣ
gives θ = 24°11' and θ = 114°11'
It is clear from tḣe derivation of Eqs (1.11) and (1.12) tḣat tḣe first value of θ corresponds to
σI wḣile tḣe second value corresponds to σII.
Finally, tḣe maximum sḣear stress is obtained from eitḣer of Eqs (1.14) or (1.15).
Ḣence from Eq. (1.15),
100.2 — (—20.2) 2
τmax = 2 = 60.2 N/mm
and will act on planes at 45° to tḣe principal planes.
S.1.2
Tḣe principal stresses are given directly by Eqs (1.11) and (1.12) in wḣicḣ σx = 50
N/mm2,
σy =–35 N/mm2, and τxy = 40 N/mm2. Tḣus, from Eq. (1.11),
3