JNTU
JNTU B.Tech III AEROSPACE VEHICLE STRUCTURES II Previous Question Paper (November/December - 2017 - R13)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
Part A
Explain the basic theory of thin plates.
Answer
The theory of thin plates, specifically Kirchhoff-Love plate theory, assumes that the plate thickness is small compared to its lateral dimensions. It posits that lines normal to the mid-surface remain straight and normal to the deformed mid-surface, and that normal stress in the thickness direction is negligible.
What are the factors that determine the angle of diagonal tension?
Answer
The angle of diagonal tension in a thin-webbed beam is primarily determined by the stiffness of the stiffeners, the spacing of the stiffeners, the thickness of the web, and the magnitude of the applied shear load relative to the buckling load of the web.
Write short notes on symmetrical bending.
Answer
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What is neutral axis?
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Mention the principle assumptions of Idealization process.
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With the help of a neat sketch show the beam with torsion loading.
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What do you mean by restraining of warping?
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Write a short note on Load discontinuities in thin walled beams.
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What are the factors that decide optimum design of sheet-stringer combinations?
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What are functions of wing ribs?
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Part B
A thin-walled pin-ended column is 2m long and has the cross-section shown in Figure 1, if the ends of the column are free to warp determine the lowest value of axial load which will cause buckling and specify the buckling mode. Take E = 75000 N/mm² and G=21000 N/mm².
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Derive the Governing differential equation for a simply supported thin rectangular plate subjected to distributed transverse load of intensity ‘q’ per unit area.
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Describe an experiment to determine the critical load of buckling for a flat panel with necessary diagrams and expressions.
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A rectangular plate a × b, simply supported along each edge, possesses a small initial curvature in its unloaded state.
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A beam having the cross-section shown in Figure 2 is subjected to a bending moment of 1500 N-m in a vertical plane. Calculate the maximum direct stress due to bending stating the point at which it acts.
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Find the angle of twist per unit length in the wing whose cross-section is shown in Figure 3 when it is subjected to a torque of 10 kN m. Find also the maximum shear stress in the section. G=25000 N/mm².
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Determine the deflection of a cantilever beam carrying a concentrated load at its free end as shown in figure 4 below.
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Calculate the shear flow distribution in the channel section shown in Figure 5 produced by a vertical shear load of 4.8 kN acting through its shear centre. Assume that the walls of the section are only effective in resisting shear stresses while the booms, each of area 300 mm², carry all the direct stresses.
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Find the position of the shear centre of the rectangular four boom beam section shown in Figure 6. 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.
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Derive the equation to find out boom areas with neat sketches and suitable structural consideration.
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What is shear lag? Show the effects of shearing strains in beams with suitable sketches and example.
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The fuselage section shown in Figure 7 is subjected to a bending moment of 100 kNm applied in the vertical plane of symmetry. If the section has been completely idealized into a combination of direct stress carrying booms and shear stress only carrying panels, determine the direct stress in each boom.
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Describe the method of calculating shear flow distributions in beams having variable stringer areas.
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Explain in detail the stresses in the fuselage components due to air load.
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Illustrate the method of calculating deflections for a multi cell wings using unit load method.
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What are the various types of wing structures? Show the construction with different types of stringers and web.
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