R09 Code No: 09A52103 SET-1 B. Tech III Year I Semester Examinations, December-2011 AEROSPACE VEHICLE STRUCTURES - II (AERONAUTICAL ENGINEERING) Time: 3 hours Max. Marks: 75 Answer any five questions All questions carry equal marks --- 1.a) What is the difference between monocoque and semi monoque structure. b) A beam having the cross-section is shown in the figure below subjected to a bending moment of 1500nm in a vertical plane. Calculate the maximum direct stress due to bending stating the point at which it acts. [7+8] 2. Illustrative give the examples of Aircraft sheet stringer elements through free-Body diagram. [15] 3. A thin walled pin ended column is 2m long and has the cross – section shown in figure below if the ends of the column are free to wrap determine the lowest value of axial load which will cause buckling and specify the buckling mode. [15] Take E = 75000 N/mm² and G = 21000 N/mm²
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R09Code No: 09A52103 SET-1 B. Tech III Year I Semester Examinations, December-2011
AEROSPACE VEHICLE STRUCTURES - II (AERONAUTICAL ENGINEERING)
Time: 3 hours Max. Marks: 75 Answer any five questions
All questions carry equal marks ---
1.a) What is the difference between monocoque and semi monoque structure. b) A beam having the cross-section is shown in the figure below subjected to a
bending moment of 1500nm in a vertical plane. Calculate the maximum direct stress due to bending stating the point at which it acts. [7+8]
2. Illustrative give the examples of Aircraft sheet stringer elements through free-Body
diagram. [15] 3. A thin walled pin ended column is 2m long and has the cross – section shown in
figure below if the ends of the column are free to wrap determine the lowest value of axial load which will cause buckling and specify the buckling mode. [15]
Take E = 75000 N/mm² and G = 21000 N/mm²
4. Determine the direct stress distribution in the thin–walled Z–section figure. Below produced by a positive bending moment Mx. [15]
5. The beam shown in figure below is simply supported at each end and carriers a load of 6000N. If all the direct stresses are resisted by the flanges and stiffeners and the web panels are effective only in shear, calculate the distribution of a axial load in the flange ABC and the stiffener BE and the shear flows in the panels. [15]
6.a) Discuss about torsion of an arbitrary section beam. b) Explain brief on I – section beam subjected to torsion with neat sketch. [7+8] 7.a) Explain the principles of stiffener/web construction? b) Write a short note on: i) Fuselage frames ii) Wing ribs. [9+6] 8.a) Explain the following terms: i) Ductility ii) Brittleness iii) Orthotropic materials IV) Plasticity b) Discuss about the torsion of a narrow Rectangular strip. [8+7]
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R09Code No: 09A52103 SET-2B. Tech III Year I Semester Examinations, December-2011
AEROSPACE VEHICLE STRUCTURES - II (AERONAUTICAL ENGINEERING)
Time: 3 hours Max. Marks: 75 Answer any five questions
All questions carry equal marks ---
1.a) Explain about the tension field webs and give some examples with neat sketch? b) What is the difference between Semi tension and complete tension field beams? [7+8] 2. Write about the failure stress in plates and stiffened panels? With neat sketch.
[15] 3. The skin of the upper side of an airplane wing made of 2024 –T6 Alclad. The
Stringer spacing is 5”, and the rib spacing is 20” .Assuming the edges to be simply supported, find the compression buckling stress for skin gages of: a) 0.040” b) 0.084” [15]
4. The cantilever beam is uniformly tapered along its length in both X and Y
directions and carriers a load of 100kn at its free end. Calculate the forces in the booms and the shear flow distribution in the walls at a section 2m from the built-in end if the boom resists all the direct stresses while the walls are effective only in shear. Each corner boom as a cross- sectional area of 900mm². While both central booms have cross- sectional areas of 1200mm². [15]
5.a) Explain briefly about types of wings and Fuselages with a neat sketch.
b) Calculate the shear stress distribution in the walls of the three – cell wing section shown below .when it is subjected to an anti-clock wise torque of 11.3KNM. [7+8]
6. Explain the condition for zero warping at a section, and derive the warping of the
cross – section. [15]
7. Find the angle twist per unit length in the wing whose cross –section is shown figure below. When it is subjected to a torque of 10KNM. Find also the maximum shear stress in the section. G = 25000 N/mm²; wall12 (outer) =900m. Nose cell area = 20,000mm². [15]
8. Explain the following terms.
a) Parallel axis theorem. b) Theorem of perpendicular axes. c) Three boom shell. d) Fuselage frames. [15]
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R09Code No: 09A52104 SET-3B. Tech III Year I Semester Examinations, December-2011
AEROSPACE VEHICLE STRUCTURES - II (AERONAUTICAL ENGINEERING)
Time: 3 hours Max. Marks: 75 Answer any five questions
All questions carry equal marks ---
1.a) Explain the Euler buckling of columns? Draw a buckling load for a perfect column and buckling load for a pin ended column?
b) Write a short note on in elastic buckling? [8+7] 2.a) Draw an axial load flow diagrams for Boom in stiffened panels?
b) Determine the deflection curve and the mid – span deflection of the simply Supported beam shown in below. The beam has a doubly symmetrical Cross – section. [6+9]
3. The pin-jointed column shown in figure below carries a compressive load applied
eccentrically at a distance from the axis of the column. Determine the maximum bending moment in the column. [15]
4.a) Show that 1/R = M/EI of Direct stress distribution with a neat sketch. b) Determine the horizontal and vertical components of the tip deflection of the
cantilever shown below the second moment of area of its un symmetrical section are Ixx, Iyy and Ixy. [7+8]
5. Draw a layout of quarter fuselage with neat sketch and layout the labels. [15]
6. A thin walled circular section beam has a diameter of 200mm and is 2m long it is firmly restrained against rotation at each end. A concentrated torque of 30KNM is applied to the beam at its mid span point. if the maximum shear stress in the beam is limited to 200N/mm and maximum angle of twist to 2 degrees . Calculate minimum thickness of the beam walls. Take G =25000 N/mm². The minimum thickness of beam corresponding to the maximum allowable shear stress of 200 N/mm² is obtained directly in which Tmax =15KNM. [15]
7. Write short notes on the following
a) Complete diagonals and in complete diagonal tension. b) Cut-outs in fuselages and cut-outs in wings. [7+8]
8. Write a short note on the following:
a) Wing torsional Divergence [ Two dimensional case ] b) Swept wing Divergence. [7+8]
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R09Code No: 09A52104 SET-4 B. Tech III Year I Semester Examinations, December-2011
AEROSPACE VEHICLE STRUCTURES - II (AERONAUTICAL ENGINEERING)
Time: 3 hours Max. Marks: 75 Answer any five questions
All questions carry equal marks ---
1.a) Explain about the Wagner’s theory of beams? Give example with neat diagram. b) What is the Tensional field beams? And explains its importance. [7+8] 2.a) Write short notes on the following:
b) Discuss the direct stress distribution due to bending with a neat sketch. [5+10] 3. Write a short note on the following :
a) Stability of beams under transverse and Axial loads b) Discuss about the Effective width. [7+8]
4. Determine the second moments of area Ixx and Iyy of the I – section below.
[15]
5. Explain briefly about the wing torsional divergence (Finite wing) with neat
diagram. [15]
6. Determine the rate of twist and the stress and the stress distribution in a circular
section bar of radius R which is subjected to equal and opposite torque T at each of its free ends. [15]
7. Calculate the deflection at the free end of the two cell beam shown in figure
below. Allowing for both bending and shear effects. The boom carries all constant thickness throughout, are effective only in shear. Take E =69000 N/mm² and G =25900 N/mm². Boom areas: B1 =B3 =B4 =B5 =B6 =650mm²; B2 =B5 =1300mm². [15]
8. Explain the following terms: a) Creep and Relaxation b) Miner’s cumulative damage theory. [7+8]
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Code No: 322102
III B.Tech. II-Semester Supplementary Examinations, November-2003
Code No:322102 -2- Set No.1 3. Write short notes on the following : (i) Instability of stiffened panels (ii) Concept of shear flow and shear lag 4. A pin ended column of length l has its central portion reinforced, the second
moment of its area being I2 while that of the end portions, each of length a, is I1. Use the energy method to determine the critical load of the column assuming that its centre line deflects into parabola y = kx(l-x) and taking the more accurate of the two expressions for the bending moment.
In the case where I2=1.6I, a=0.2l, find the percentage increase in strength due to reinforcement and compare it with percentage increase in weight on the basis that the radius of gysation of the section is not altered.
5. Determine the shear flow distribution in the thin walled Z-section as shown in
figure due to shear load Sy applied through the shear centre of the section.
6. Determine the working distribution in the doubly symmetrical, rectangular, closed
tube as shown in figure when subjected to an anti-clockwise torque T.
Code No:322102 -3- Set No.1 7. The idealised single cell, thin walled tube, shown in figure has a horizontal axis of
symmetry. Direct stresses are carried by booms B1 to B8 while the walls, which are straight, are effective only in carrying whear stresses. The tube is loaded by vertical shear force of 10000 N acting in the plane of booms 3 amd 6. Assuming that the direct stresses are distributed according to E.T.B. Calculate the distribution of shear flow around the section.
Answer any FIVE questions All question carry equal marks
--- 1. Find the bending stress in each stringer of the wing cross section as shown in
figure. The section properties about the X and Z axes through the centriod are Ix=71.23 in4, Iz=913.713 in4 and Ixz=5.30 in4. The wing bending moments at the cross-section are Mx=460000 in-lb and MZ=42500 in-lb. The coordinates of the stringer areas are as in Table.
2. Discuss the concept of effective width. Derive its value for a simply supported
sheet and for a sheet with one side simply supported and other free. 3. Calculate the shear flow distribution in the channel section shown in figure,
produced by a vertical load of 48000 N acting through its shear centre. Assume that the skin is effective on in resisting shear stresses while the booms, each of area 300 mm2, resist all the direct stresses.
Code No:322102 -2- Set No.2 4. Find the position of the shear centre of the rectangular four boom tube shown in
figure. The booms carry only direct stresses but the skin is fully effective in carrying both shear and direct stress. The area of each boom is 100 mm2.
5. Find the equation of short column curve for the extrusion shown in figure, if the
material is 24S-T with E=10700000, n=10 and f1=37000, K=3.62
For area (1), t
b=31.3 and F=29000; For area (2),
t
b= 7.52 and F=45000
6. Consider a complete tension field beam shown in figure. Draw free body
diagram for stiffness ( end and central) and flanges and plot axial loads in them. Take = 450 and t = 0.001 m.
3. By using Rayleigh-Ritz method find the critical load of a cantilever column by assuming a displacement function.
= AZ2 + BZ3
4. A thin square plate of side a and thickness t is simply supported along each edge and has a slight initial curvature giving an initial deflected shape.
Wo = sin a
y
a
x sin
If the plate is subjected to a uniform compressive stress in the x-direction, find an expression for the elastic deflection w normal to the plate. Show also that the deflection at the mid point of the plate can be presented in the form of a south well plot and illustrate your answer with a suitable sketch.
5. The beam shown in figure is assumed to have a pure tension field web. Draw free
body diagrams for the stiffness and flanges and plot the axial loads in the stiffness and flanges. Assume the tension diagonal angle as 450
Code No:322102 -2- Set No.4 4. A tubular column of length l is tapered in wall thickness so that the area and
second moment of area of its cross-section decreases uniformly from A1 and I1 at its centre to 0.2 A1 and 0.2 I1 at its ends. Assuming a deflected centre line of parabolic form, and taking the more correct form for the bending moment, use the energy method to estimate its critical load when tested between pin centres, in terms of the above data and Young’s modulus E. Hence show that the saving in weight by using such a strut instead of one having the same radius of gyration and constant thickness is about 15%.
5.a) What are tension field beams? Consider a beam having top and bottom flanges
and vertical stiffner uniformly spaced at a distance d along the span. The beam has thin web. Derive a formulation to determine the load carrying capacity of the beam.
b) Discuss semi-tension field beams. 6. Find the shear centre for the wing cross section shown in figure. Web (3) has a
thickness of 0.064 in and the other webs have thickness of 0.040 in. Assume G constant for all other sections. The cross section is symmetrical about a horizontal axis.
7. Find the bending moment at any point of the semi-circular arch shown in figure, if
the supports do not move. The value of EI is constant for all cross-sections.
III B.Tech II Semester Regular Examinations, April/May 2004
AEROSPACE STRUCTURES - II (Aeronautical Engineering)
Time: 3 hours Max. Marks:80 Answer any FIVE questions
All questions carry equal marks - - -
1. A cantilever of “Z” section is built in at one end and twisted by a couple Mt
applied at the other end. Find the angle of twist and maximum Bending Moment in the flanges.
2. Describe Nedham’s method of calculation of crippling stresses.
3. Fig a shows a corner member in a stiffened wing section. The skin is fastened to the stiffener by one row of 3.2mm diameter rivet at 19 mm spacing. Thickness of skin is 0.9 mm and thickness of stiffener is 1.3 mm. The web is fastened to stiffener by 2 staggered rows of rivets with rivet spacing in each of 28mm and rivets are of flat head type. Material is 2024-73 Aluminum alloy. Find effective sheet widths and total failing load unit will carry.
Code No.: NR- 322102 -2- Set.No:1 4. The beam shown in the Fig is assumed to have a pure tension field web. Plot the
axial loads in the stiffeners and flanges. Assume angle of tension diagonal = 45
5. A timber joist, 100 mm wide and 200 mm deep, is freely supported over a span of
4 mts. It is subjected to a BM of 3 x 10 N - mm at the central section, the trace of the plane of loading being inclined at 30° to the principal axis V-V. Locate the neutral axis and calculate the maximum bending stress induced. If the BM is due to a load of 6000 N uniformly distributed over the whole span, calculate the central deflection. E = 10 N/mm ².
6. Calculate the internal shear flow for the multcell tube system subjected to
a torsion of 10,000 NCm, for 1 mm thick section cells as shown. Take G = 20 Gpa.
7. Determine shear center of thin walled rectangular cross-section in which there is
narrow longitudinal slit. The thickness ‘t’ is constant throughout the section.
Code No.: NR- 322102 -2- Set.No:1 8. Figure shows the regular hexagonal cross-section of a thin walled beam of sides
‘a’ and constant wall thickness ‘t’. The beam is subjected to a traverse shear force ‘S’, its line of action being along a side of the hexagon as shown. Find the rate of twist of the beam in terms of ‘t’, ‘a’ and ‘s’ and shear modulus ‘G’. Plot the shear flow distribution around the section, with values in terms of ‘S’ and ‘a’.
Code No.: NR- 322102 III B.Tech II Semester Regular Examinations, April/May 2004
AEROSPACE STRUCTURES - II (Aeronautical Engineering)
Time: 3 hours Max. Marks:80 Answer any FIVE questions
All questions carry equal marks - - -
1. A cantilever of “I”section is built in at one end and twisted by a couple Mt applied at the other end. Find the angle of twist and maximum Bending Moment in the flanges.
2. Describe Gerard’s method of calculation of crippling stress.
3. The figure shows a corner member in a stiffened wing section. The skin is fastened to the stiffener by one row of 3.2mm diameter rivet at 19mm spacing. Thickness of skin is 0.8 mm and thickness of stiffener is 1.2 mm. The web is fastened to stiffener by 2 staggered rows of rivets with rivet spacing in each of 28mm and rivets are of flat head type. Material is 2024-73 Aluminum alloy. Find the crippling stress for stiffener. Will inter rivet buckling occur?
Code No.: NR- 322102 -2- Set.No:2 4. For the beam shown in the figure plot the axial loads in the flanges and stiffeners
and flanges. Compute flange-bending moments and load per mm on all rivets.
5. An lSMB 300 mm x 140 mm rolled steel beam carries at a certain section, a BM
‘M’, the trace of the plane of loading being inclined at 15° to the V V axis. If Iuu = 8603.6 x 104 mm ² and Iv v = 453.9 x 104 mm4 , evaluate M if the maximum bending stress induced in the section is 120 N/mm ².
6. Calculate the shear flow for the given fig. And also find out twist length. The
torque applied on the member is 2,000 Ncm. Take G = 80 Gpa and thickness as 0.1 cm.
7. Locate the shear center ‘O’ for thin unbalanced I – section shown in figure.
Assume thickness ‘t’ constant throughout the section.
Code No.: NR- 322102 -3- Set.No:2 8. Find the position of the shear center of the rectangular four boom beam section
shown in figure. The booms carry only direct stresses but the skin is fully effective in carrying both shear and direct stress. The area of each boom is 100 mm².
Code No.: NR- 322102 III B.Tech II Semester Regular Examinations, April/May 2004
AEROSPACE STRUCTURES - II (Aeronautical Engineering)
Time: 3 hours Max. Marks:80 Answer any FIVE questions
All questions carry equal marks - - -
1. A cantilever of cross section as shown in fig. is built in at one end and twisted by a couple Mt applied at the other end. Find the angle of twist and maximum Bending Moment in the flanges.
2. Write short notes on
a) Nedham’s method b) Gerard’s method
3. Stiffener of flange member is an extrusion of 7075-T6 Aluminum alloy. Skin and web sheets are 7075-T6 Aluminum alloy. Thickness of skin is 0.9 mm and thickness of stiffener is 1.3 mm. Skin is fastened to stiffener by two rows of 3.2mm diameter rivets of brazier head type space 22mm apart. The web is attached to the stiffener by one row of 5mm diameter rivets spaced 25mm apart. Determine the effective skin area and total compressive load that the unit can carry.
Code No.: NR- 322102 -2- Set.No:3 4. For the beam shown in Fig., determine the angle of the tension diagonal if
td/ Ae = 5.0.
5. A beam of rectangular section, 80 mm wide and 120 mm deep is subjected to a
BM of 120 N-m. The trace of the plane of loading is inclined at 45 to the V-V axis of the section. Locate the neutral axis of the section. Find the bending stress by neutral axis method.
6. Determine the shear flow and twist / length for the multi cell configuration shown
in the figure. Take shear modulus as G = 40 Gpa. Applied Twisting moment = 10,000 N-Cm.
7. Determine shear center of ray of a thin walled cylindrical section shown in figure
subjected to vertical load. Thickness is constant throughout the section, ‘t’.
8. The thin walled single cell beam shown in figure has been idealized into combination of direct stress carrying booms and shear stress only carrying walls. If the section supports a vertical shear load of 10 KN acting in a vertical plane through booms 3 and 6, calculate the distribution of shear flow round the section.
Code No.: NR- 322102 -2- Set.No:4 6. Calculate the shear flow and twist / length for the geometrical configuration
shown in the figure for an applied torque of 20,000 N – Cm. The member is of uniform thickness of 0.1 Cm. Take G = 40 Gpa. Use method of successive approximation.
7. Plot shear stress across I-section as shown. t = thickness.
8. The doubly symmetrical fuselage section shown in figure has been idealized into
an arrangement of direct stress carrying booms and shear stress carrying skin panels; the boom areas are all 150 mm². Calculate the direct stresses in the booms and the shear flows in the panels when the section is subjected to shear load of 50 KN and a bending moment of 100 KN.
III B.Tech II Semester Supplimentary Examinations,January 2010AEROSPACE VEHICLE STRU.-II
Aeronautical EngineeringTime: 3 hours Max Marks: 80
Answer any FIVE QuestionsAll Questions carry equal marks
? ? ? ? ?
1. Thin walled circular beam cross section is subjected to transverse load F. Determinethe variation of shear flow through out the cross-section as shown in figure 1. [16]
Figure 1
2. Explain in detail the stresses in the fuselage components due to air load? [16]
3. (a) Explain the difference in the buckling behaviour of solid and thin walledcolumns
(b) Find the shear flow in each web of the tapered beam shown in the figure3b. Plot the distribution of axial load along each stiffening member whenP1=20kN and P2=10kN. All dimensions are in cm. [6+10]
Figure 3b
4. (a) What do you mean by plastic buckling of a flat sheet? Define L/ρ of equivalentcolumn for different conditions.
(b) For the wing part shown in figure 4b, Radius of curvature ‘R’ = 1250mm,sheet thickness ‘t’ = 1.5mm, span between stringers ‘b’ = 150mm and therib spacing ‘L’ = 450mm. Find the compressive stress in the skin at whichbuckling occurs, if E = 70GPa. [6+10]
Figure 4b
5. Explain what do you mean by effective wall and ineffective wall related to beams.Define boom show composite beams with boom, flanges and webs. [16]
6. (a) Derive an expression for the angle of diagonal tension.
(b) Find the shear flow in each web of the beam shown in the figure 6b. Plot thedistribution of axial load along each stiffening member when P1=20kN andP2=10kN. All dimensions are in cm. [6+10]
Figure 6b
7. (a) What are the various structural elements used in airplane wings? Explaintheir role with respect to different types of loads.
(b) Find crippling stress of rectangular tubes shown in figure 7b using Nedham’smethod, when formed from aluminium. Uniform thickness, t = 1.5mm. [8+8]
Figure 7b
8. (a) Explain the following methods of reducing stress concentration
(b) A round shaft made of cold finished AISI 1020 steel is subjected to a variabletorque whose maximum value is 700 KN-m. For a factor of safety of 1.5 onthe Soderberg criterion, determine the diameter of the shaft if
i. The torque is reversed
ii. The torque varies from zero to maximum
iii. The torque varies from 300 N m to a maximum.
Assume,Correction factor for type of Loading other than bending=0.6Size correction factor =0.85Surface correction factor =0.87.Ultimate tensile strength =550MPa.Yield strength =460MPa. [4+12]
III B.Tech II Semester Supplimentary Examinations,January 2010AEROSPACE VEHICLE STRU.-II
Aeronautical EngineeringTime: 3 hours Max Marks: 80
Answer any FIVE QuestionsAll Questions carry equal marks
? ? ? ? ?
1. Bending stress in a machine past fluctuates between a tensile stress of 280MPaand compressive stress of 140MPa. What should be the minimum ultimate tensilestrength to carry this fluctuation I definitely according to:
(a) Gerber’s formula
(b) Goodman’s formula
(c) Soderberg’s formula. [16]
2. (a) What are monocoque and semi-monocoque structures? Explain briefly withsuitable examples.
(b) The beam shown in figure 2b is assumed to have a pure tension field web.Draw free body diagrams for the stiffeners and flanges and plot the axial loadsin the stiffeners and flanges. Assume α = 450. All dimensions are in mm.[4+12]
Figure 2b
3. (a) Explain critical crippling load for extruded sections and bent sheet sections.
(b) A thin-walled pin-ended column is 2m long and has the section as shown infigure 3. If the ends of the column are free to warp, determine the lowest valueof flexural-torsional buckling load. Take E=75GPa and G=30GP. [6+10]
4. (a) Explain shear buckling stress in curved plates.
(b) A straight uniform column of length ‘L’ and bending stiffness ‘EI’ is subjectedto uniform lateral loading w/unit length. The end attachments do not restrictrotation of the column ends. The longitudinal; compressive force ‘P’ haseccentricity ‘e’ from the centroids of the end sections and is placed so as tooppose the bending effect of the lateral loading. The eccentricity e can bevaried and is to be adjusted to the value which, for given values of P and w,will result in the least maximum bending moment of the column. Show thate = (w/Pa2) tan2aL/4 where a = P/EI. Shown in figure 4b. [6+10]
Figure 4b
5. Define shear flow? Explain the concept of shear flow in thin walled beams with thehelp of a neat sketch. [12+4]
6. The fuselage of light weight passenger carrying aircraft has the circular cross Sec-tion shown in figure 6. The cross-sectional area of each stringer is 100 mm2 andthe vertical distances given in figure are the mid line of the section wall at the cor-responding srtringer positions. The fuselage is subjected to transverse shear loadof 100 kN acting through the shear centre together with pure torque equal to 15 ×106 Nmm. Calculate the shear flow distribution. [16]
Figure 6
7. Thickness is uniform locate the shear centre for the two compartment box beam. t= 10 mm, b= 500 mm. Also draw the shear flow variation. Shown in figure 7. [16]
8. (a) Explain the influence of support conditions on buckling stress of a flat squareplate.
(b) Determine the crippling stress of the panel, formed with hat-section stiffeners,as shown in figure 8b. Take σcy=470MPa and E=70GPa for stiffeners whileσcy=280MPa. [6+10]
III B.Tech II Semester Supplimentary Examinations,January 2010AEROSPACE VEHICLE STRU.-II
Aeronautical EngineeringTime: 3 hours Max Marks: 80
Answer any FIVE QuestionsAll Questions carry equal marks
? ? ? ? ?
1. (a) Explain buckling waves in a simply supported flat plate.
(b) Determine the buckling strength of a panel, comprising flat sheet and uni-formly spaced Z-section stringers, a part of whose cross section is shown infigure 1, under uniform compressive loads. [4+12]
Figure 1
2. (a) Explain critical buckling stress for a stiffened panel and how it differs fromthat of a flat plate.
(b) Calculate crippling stress for the given extrusion section. Assume E=75 GPa,Thickness of web is 1.5mm and thickness of flanges is 2mm. Shown in figure2b. [6+10]
Figure 2b
3. (a) Explain different types of wing structures.
(b) Explain the advantages and disadvantages of different materials used for air-craft structures.
(c) Explain Wagner’s theory. [4+6+6]
4. Derive the equation for shear flow in the flange and web of thin walled I-section.Plot the shear flow variation. [16]
5. What is structural idealization? Sketch the structural idealization for wing andfuselage? [4+12]
6. (a) Explain the following methods of reducing stress concentration
(b) A shaft is made of steel [ultimate tensile strength 700MPa and yield point420MPa] is subjected to a torque varying from 200Nm anti -clock wise to600Nm clockwise. Calculate the diameter of the shaft if the factor of safety is2 and it is based on the yield point and the endurance strength in shear.
[6+10]
7. A hexagonal tube is subjected to a torque of 150 N-m. Determine the mean dimen-sion ‘a’ of its sides. If the allowable shear stress is τallo = 60 M Pa. Each side ishaving uniform thickness t=3mm. Determine the Max. angle of twist is possible,if it is made of Aluminum, G = 26 G Pa. shown in figure 7. [16]
Figure 7
8. (a) Explain shear buckling stress in curved plates.
(b) Find the shear flow in each web of the tapered beam shown in the figure8b. Plot the distribution of axial load along each stiffening member whenP1=20kN and P2 =10kN. All dimensions are in cm. [6+10]
III B.Tech II Semester Supplimentary Examinations,January 2010AEROSPACE VEHICLE STRU.-II
Aeronautical EngineeringTime: 3 hours Max Marks: 80
Answer any FIVE QuestionsAll Questions carry equal marks
? ? ? ? ?
1. What are the various functions of structural components? [16]
2. (a) Explain the following methods of reducing stress concentration:
i. Removal of undesired material
ii. Added grooves.
(b) A steel connecting rod is subjected to a completely reversed axial load of120kN.Suggest the suitable size of the rod using a factor of safety 1.8. Theultimate strength of the material is 1000MPa.Load correction factor 0.7Size factor 0.85Surface finish factor 0.8 [8+8]
3. (a) Explain the influence of support conditions on buckling stress of a flat squareplate.
(b) Determine the buckling strength of a panel, comprising flat sheet and uni-formly spaced Z-section stringers, a part of whose cross section is shown infigure 3b, under uniform compressive loads. [6+10]
Figure 3b
4. Uniform thickness t = 5mm, Determine the torque T to produce an angle of twist0.12 radians over span of 2m, for the beam Shown in figure 4 determine the averagestress in the member. Also calculate the strain energy stored. All dimensions arein mm. [10+3+3]
(b) A column of length ‘2L’ with doubly symmetrical cross section of a thin-walledcolumn with doubly symmetric cross-section shown in figure 7b is compressed,preventing warping and twisting of its ends. Determine the average compres-sive stress at which the column first buckles in torsion. Take L=500mm,b=25mm, t=2.5mm and E=70GPa. [6+10]
Figure 7b
8. (a) Derive the relationship for shear force at any section of a tapered diagonaltension field beam, subjected to a load at its free end perpendicular to theaxis in the plane of the beam.
(b) Find the shear flow in each web of the beam shown in the figure 8b. Plotthe distribution of axial load along each stiffening member when P1=20kN,P2=15kN and P3=10kN. All dimensions are in cm. [6+10]
Time: 3 hours Max. Marks: 80 Answer any five questions
All questions carry equal marks ---
1. a) Derive an expression for the angle of diagonal tension. b) Find the shear flow in each web of the beam shown in the figure 1. Plot the distribution of axial load along each stiffening member when P1=20 kN, P2=15 kN and P3=10 kN. All dimensions are in cm. [6+10]
Figure: 1
2. a) Explain the effect of riveting a long flat plate to a stiffener at regular intervals, in terms of its buckling response. b) Calculate crippling stress for the given extrusion section. Assume E=75 GPa, Thickness of web is 1.5mm and thickness of flanges is 2mm. Shown in figure 2b. [6+10]
Figure: 2b
3. a) What is buckling coefficient? Plot its variation for a thin rectangular plate, simply supported along its four edges, as a function of ratio of its sides. b) A straight uniform column of length ‘L’ and bending stiffness ‘EI’ is subjected to uniform lateral loading w/unit length. The end attachments do not restrict rotation of the column ends. The longitudinal; compressive force ‘P’ has eccentricity ‘e’ from the centroids of the end sections and is placed so as to oppose the bending effect of the lateral loading. The eccentricity e can be varied and is to be adjusted to the value which, for given values of P and w, will result in the least maximum bending moment of the column. Show that e = (w/Pa2) tan2aL/4 where a = P/EI. Show in figure 3b. [6+10]
4. a) Explain the influence of support conditions on buckling stress of a flat square plate. b) A simply supported panel is 600 mm wide and 1200 mm long. The 3mm thick panel is stiffened on both sides by angle section longitudinal stiffeners with 150mm spacing, as shown in figure 4b. Determine the compressive stress which produces buckling of the panel. Take A=50 mm2, I (through centroid) = 500 mm4 and distance of centroid from the center of panel and z=3mm for the stiffeners and E=70GPa. [4+12]
Figure: 4b
5. Derive the shear stress equation for rectangular beam of breadth ‘b’, depth ‘d’. Also plot the variation of shear stress. Derive the relation for max av/τ τ . [6+6+4] 6. A hexagonal tube is subjected to a torque of 150 N-m. Determine the mean dimension ‘a’ of its sides. If the allowable shear stress is alloτ = 60 M Pa. Each side is having uniform thickness t=3mm. Determine the Max. angle of twist is possible, if it is made of Aluminum, G = 26 G Pa. shown in figure 6. [16]
Figure: 6
7. Explain in detail the stresses in the fuselage components due to air load? [16] 8. a) Explain notch sensitivity. b) A circular bar of 0.5 m length is supported freely at its two ends It is acted upon by a central concentrated cyclic load having a minimum value of 20 k N and a maximum value of 50 k N. Determine the diameter of bar by taking a factor of safety of 1.5, size factor of 0.85, surface finish factor of 0.9. The material properties of bars are given by: Ultimate strength of 650 MPa, Yield strength of 500 MPa, and Endurance strength of 350 MPa. [4+12]
Time: 3 hours Max. Marks: 80 Answer any five questions
All questions carry equal marks ---
1. a) What is buckling coefficient? Plot its variation for a thin rectangular plate, simply supported along its four edges, as a function of ratio of its sides. b) A straight uniform column of length ‘L’ and bending stiffness ‘EI’ is subjected to uniform lateral loading w/unit length. The end attachments do not restrict rotation of the column ends. The longitudinal; compressive force ‘P’ has eccentricity ‘e’ from the centroids of the end sections and is placed so as to oppose the bending effect of the lateral loading. The eccentricity e can be varied and is to be adjusted to the value which, for given values of P and w, will result in the least maximum bending moment of the column. Show that e = (w/Pa2) tan2aL/4 where a = P/EI. Show in figure 3b. [6+10]
Figure: 3b
2. a) Explain the influence of support conditions on buckling stress of a flat square plate. b) A simply supported panel is 600 mm wide and 1200 mm long. The 3mm thick panel is stiffened on both sides by angle section longitudinal stiffeners with 150mm spacing, as shown in figure 4b. Determine the compressive stress which produces buckling of the panel. Take A=50 mm2, I (through centroid) = 500 mm4 and distance of centroid from the center of panel and z=3mm for the stiffeners and E=70GPa. [4+12]
Figure: 4b
3. Derive the shear stress equation for rectangular beam of breadth ‘b’, depth ‘d’. Also plot the variation of shear stress. Derive the relation for max av/τ τ . [6+6+4]
4. A hexagonal tube is subjected to a torque of 150 N-m. Determine the mean dimension ‘a’ of its sides. If the allowable shear stress is alloτ = 60 M Pa. Each side is having uniform thickness t=3mm. Determine the Max. angle of twist is possible, if it is made of Aluminum, G = 26 G Pa. shown in figure 6. [16]
Figure: 6
5. Explain in detail the stresses in the fuselage components due to air load? [16] 6. a) Explain notch sensitivity. b) A circular bar of 0.5 m length is supported freely at its two ends It is acted upon by a central concentrated cyclic load having a minimum value of 20 k N and a maximum value of 50 k N. Determine the diameter of bar by taking a factor of safety of 1.5, size factor of 0.85, surface finish factor of 0.9. The material properties of bars are given by: Ultimate strength of 650 MPa, Yield strength of 500 MPa, and Endurance strength of 350 MPa. [4+12] 7. a) Derive an expression for the angle of diagonal tension. b) Find the shear flow in each web of the beam shown in the figure 1. Plot the distribution of axial load along each stiffening member when P1=20 kN, P2=15 kN and P3=10 kN. All dimensions are in cm. [6+10]
Figure: 1
8. a) Explain the effect of riveting a long flat plate to a stiffener at regular intervals, in terms of its buckling response. b) Calculate crippling stress for the given extrusion section. Assume E=75 GPa, Thickness of web is 1.5mm and thickness of flanges is 2mm. Shown in figure 2b. [6+10]
Time: 3 hours Max. Marks: 80 Answer any five questions
All questions carry equal marks ---
1. Derive the shear stress equation for rectangular beam of breadth ‘b’, depth ‘d’. Also plot the variation of shear stress. Derive the relation for max av/τ τ . [6+6+4] 2. A hexagonal tube is subjected to a torque of 150 N-m. Determine the mean dimension ‘a’ of its sides. If the allowable shear stress is alloτ = 60 M Pa. Each side is having uniform thickness t=3mm. Determine the Max. angle of twist is possible, if it is made of Aluminum, G = 26 G Pa. shown in figure 6. [16]
Figure: 6
3. Explain in detail the stresses in the fuselage components due to air load? [16] 4. a) Explain notch sensitivity. b) A circular bar of 0.5 m length is supported freely at its two ends It is acted upon by a central concentrated cyclic load having a minimum value of 20 k N and a maximum value of 50 k N. Determine the diameter of bar by taking a factor of safety of 1.5, size factor of 0.85, surface finish factor of 0.9. The material properties of bars are given by: Ultimate strength of 650 MPa, Yield strength of 500 MPa, and Endurance strength of 350 MPa. [4+12] 5. a) Derive an expression for the angle of diagonal tension. b) Find the shear flow in each web of the beam shown in the figure 1. Plot the distribution of axial load along each stiffening member when P1=20 kN, P2=15 kN and P3=10 kN. All dimensions are in cm. [6+10]
6. a) Explain the effect of riveting a long flat plate to a stiffener at regular intervals, in terms of its buckling response. b) Calculate crippling stress for the given extrusion section. Assume E=75 GPa, Thickness of web is 1.5mm and thickness of flanges is 2mm. Shown in figure 2b. [6+10]
Figure: 2b
7. a) What is buckling coefficient? Plot its variation for a thin rectangular plate, simply supported along its four edges, as a function of ratio of its sides. b) A straight uniform column of length ‘L’ and bending stiffness ‘EI’ is subjected to uniform lateral loading w/unit length. The end attachments do not restrict rotation of the column ends. The longitudinal; compressive force ‘P’ has eccentricity ‘e’ from the centroids of the end sections and is placed so as to oppose the bending effect of the lateral loading. The eccentricity e can be varied and is to be adjusted to the value which, for given values of P and w, will result in the least maximum bending moment of the column. Show that e = (w/Pa2) tan2aL/4 where a = P/EI. Show in figure 3b. [6+10]
Figure: 3b
8. a) Explain the influence of support conditions on buckling stress of a flat square plate. b) A simply supported panel is 600 mm wide and 1200 mm long. The 3mm thick panel is stiffened on both sides by angle section longitudinal stiffeners with 150mm spacing, as shown in figure 4b. Determine the compressive stress which produces buckling of the panel. Take A=50 mm2, I (through centroid) = 500 mm4 and distance of centroid from the center of panel and z=3mm for the stiffeners and E=70GPa. [4+12]
Time: 3 hours Max. Marks: 80 Answer any five questions
All questions carry equal marks ---
1. Explain in detail the stresses in the fuselage components due to air load? [16] 2. a) Explain notch sensitivity. b) A circular bar of 0.5 m length is supported freely at its two ends It is acted upon by a central concentrated cyclic load having a minimum value of 20 k N and a maximum value of 50 k N. Determine the diameter of bar by taking a factor of safety of 1.5, size factor of 0.85, surface finish factor of 0.9. The material properties of bars are given by: Ultimate strength of 650 MPa, Yield strength of 500 MPa, and Endurance strength of 350 MPa. [4+12] 3. a) Derive an expression for the angle of diagonal tension. b) Find the shear flow in each web of the beam shown in the figure 1. Plot the distribution of axial load along each stiffening member when P1=20 kN, P2=15 kN and P3=10 kN. All dimensions are in cm. [6+10]
Figure: 1
4. a) Explain the effect of riveting a long flat plate to a stiffener at regular intervals, in terms of its buckling response. b) Calculate crippling stress for the given extrusion section. Assume E=75 GPa, Thickness of web is 1.5mm and thickness of flanges is 2mm. Shown in figure 2b. [6+10]
5. a) What is buckling coefficient? Plot its variation for a thin rectangular plate, simply supported along its four edges, as a function of ratio of its sides. b) A straight uniform column of length ‘L’ and bending stiffness ‘EI’ is subjected to uniform lateral loading w/unit length. The end attachments do not restrict rotation of the column ends. The longitudinal; compressive force ‘P’ has eccentricity ‘e’ from the centroids of the end sections and is placed so as to oppose the bending effect of the lateral loading. The eccentricity e can be varied and is to be adjusted to the value which, for given values of P and w, will result in the least maximum bending moment of the column. Show that e = (w/Pa2) tan2aL/4 where a = P/EI. Show in figure 3b. [6+10]
Figure: 3b
6. a) Explain the influence of support conditions on buckling stress of a flat square plate. b) A simply supported panel is 600 mm wide and 1200 mm long. The 3mm thick panel is stiffened on both sides by angle section longitudinal stiffeners with 150mm spacing, as shown in figure 4b. Determine the compressive stress which produces buckling of the panel. Take A=50 mm2, I (through centroid) = 500 mm4 and distance of centroid from the center of panel and z=3mm for the stiffeners and E=70GPa. [4+12]
Figure: 4b
7. Derive the shear stress equation for rectangular beam of breadth ‘b’, depth ‘d’. Also plot the variation of shear stress. Derive the relation for max av/τ τ . [6+6+4] 8. A hexagonal tube is subjected to a torque of 150 N-m. Determine the mean dimension ‘a’ of its sides. If the allowable shear stress is alloτ = 60 M Pa. Each side is having uniform thickness t=3mm. Determine the Max. angle of twist is possible, if it is made of Aluminum, G = 26 G Pa. shown in figure 6. [16]
