Anna University Chennai 2006 M.E AN132 - AC Strustures - Question Paper
AN132 - AC Strustures
3)-i. v-t
M.E. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2006.
First Semester Aeronautical Engineering AN 132 AIRCRAFT STRUCTURES (Regulation 2002)
Time : Three hours Maximum : 100 marks
Answer ALL questions.
PART A (10 x 2 = 20 marks)
1. Sketch a semi-monocoque wing and state the assumptions made in its analysis.
2. Distinguish between symmetric and unsymmetric berating. Give examples.
3. Define principal axes and give an expression to determine it.
4. Define shear center and mark shear center
(a) channel section
(b) equal section.
5. Show that for a curved web the resultant force of a shear flow R = qL.
6. Give the expression for angle of twist for a thin walled closed section subjected to torque.
7. What is safe life and fail safe design?
8. Sketch buckling modes for a sheet in
(a) Compression
(b) Shear.
9. Why are Lips and Bulbs provided in extruded sections?
10. Explain effective width and give an expression to determine
. PART B (5 x 16 = 80 marks)
11. (a) A box beam with 50 cm length is subjected to loads Px = 8 kN and Py = 25kN as shown in the fig.l. The stringer areas are 3 cm2 each. Find the maximum bending stress.
 |
|
& 40 c*' |
Fig.l
Or
(b) Find the max. bending stress for the section shown in the fig.2, subjected to a bending moment Mx = 1500 N - m .
, H-M-
ov -
.
Fig.2
12. (a) Derive an expression for shear flow of an open tube of arbitrary cross-
section subjected to shear loads Sx & Sy without twist and modify this
expression for a closed tube.
Or
(b) Find the shear flow distribution in a thin walled Z-section, whose thickeness is t, height h, flange width h/2 and subjected to a shear Sy
through the shear center.
13. (a) Find the shear flow and shear center for the open section shown in the
fig.3. The area of strings are, a = b = 6 cm2, c = d = 2.5 cm2. A vertical load of lOkN acts through the shear center.
Fig.3
Or
IT 'lT '
(b) Find the shear flow of the closed tube shown in the fig.4. The area of stringers are, a = a = c = c = l cm2, b = b = 2 cm2.
 |
|
Fig.4 |
14. (a) Find the shear flow for the two cell structure shown in fig.5. The stringer areas are a = a = 4 cm2, c = c = e = e = 2 cm2, b = b = d = d = l cm2. The vertical webs a-a and e-e have 1.5 mm thickness and the remaining walls have 1 mm thickness each.
I5000A
T
L
A
CL
Fig.5
Or
(b) Find the shear flow and twist per unit length of the three cell tube made ' of Aluminium as shown in the fig.6 and subjected to a Torque 75,000 N-cm. E = 70 Gpa.
rw
|
l1'"* I |
 |
|
f*-2S -v| Fig.6 |
15. (a) (i) Explain, buckling, local buckling and crippling with suitable examples. (6)
(ii) Explain Needham's method to determine crippling strength. (10)
Or
(b) (i) An Aluminium alloy Z section with 1.5 mm uniform thickness, flange width = 2 cm and web height = 4 cm is subjected to compression. Find the local buckling stress if Kw = 2.9 and E = 70 Gpa. (5)
(ii) Explain Inter-Rivet buckling. (5)
(iii) Explain principle of Semi-Tension field beam. (6)
3)-i. v-t
M.E. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2006.
First Semester Aeronautical Engineering AN 132 AIRCRAFT STRUCTURES (Regulation 2002)
Time : Three hours Maximum : 100 marks
Answer ALL questions.
PART A (10 x 2 = 20 marks)
1. Sketch a semi-monocoque wing and state the assumptions made in its analysis.
2. Distinguish between symmetric and unsymmetric berating. Give examples.
3. Define principal axes and give an expression to determine it.
4. Define shear center and mark shear center
(a) channel section
(b) equal section.
5. Show that for a curved web the resultant force of a shear flow R = qL.
6. Give the expression for angle of twist for a thin walled closed section subjected to torque.
7. What is safe life and fail safe design?
8. Sketch buckling modes for a sheet in
(a) Compression
(b) Shear.
9. Why are Lips and Bulbs provided in extruded sections?
10. Explain effective width and give an expression to determine
. PART B (5 x 16 = 80 marks)
11. (a) A box beam with 50 cm length is subjected to loads Px = 8 kN and Py = 25kN as shown in the fig.l. The stringer areas are 3 cm2 each. Find the maximum bending stress.
 |
|
& 40 c*' |
Fig.l
Or
(b) Find the max. bending stress for the section shown in the fig.2, subjected to a bending moment Mx = 1500 N - m .
, H-M-
ov -
.
Fig.2
12. (a) Derive an expression for shear flow of an open tube of arbitrary cross-
section subjected to shear loads Sx & Sy without twist and modify this
expression for a closed tube.
Or
(b) Find the shear flow distribution in a thin walled Z-section, whose thickeness is t, height h, flange width h/2 and subjected to a shear Sy
through the shear center.
13. (a) Find the shear flow and shear center for the open section shown in the
fig.3. The area of strings are, a = b = 6 cm2, c = d = 2.5 cm2. A vertical load of lOkN acts through the shear center.
Fig.3
Or
IT 'lT '
(b) Find the shear flow of the closed tube shown in the fig.4. The area of stringers are, a = a = c = c = l cm2, b = b = 2 cm2.
 |
|
Fig.4 |
14. (a) Find the shear flow for the two cell structure shown in fig.5. The stringer areas are a = a = 4 cm2, c = c = e = e = 2 cm2, b = b = d = d = l cm2. The vertical webs a-a and e-e have 1.5 mm thickness and the remaining walls have 1 mm thickness each.
I5000A
T
L
A
CL
Fig.5
Or
(b) Find the shear flow and twist per unit length of the three cell tube made ' of Aluminium as shown in the fig.6 and subjected to a Torque 75,000 N-cm. E = 70 Gpa.
rw
|
l1'"* I |
 |
|
f*-2S -v| Fig.6 |
15. (a) (i) Explain, buckling, local buckling and crippling with suitable examples. (6)
(ii) Explain Needham's method to determine crippling strength. (10)
Or
(b) (i) An Aluminium alloy Z section with 1.5 mm uniform thickness, flange width = 2 cm and web height = 4 cm is subjected to compression. Find the local buckling stress if Kw = 2.9 and E = 70 Gpa. (5)
(ii) Explain Inter-Rivet buckling. (5)
(iii) Explain principle of Semi-Tension field beam. (6)
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Attachment: |
| Earning: Approval pending. |
