JNTU
JNTU B.Tech III AEROSPACE VEHICLE STRUCTURES II Previous Question Paper (May/June - 2019 - R13)
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
Discuss about local instability.
Answer
Local instability, or local buckling, occurs when individual thin elements of a structural member, such as the flange or web of an I-beam, buckle under compressive stress before the entire member reaches its overall failure load. It is characterized by localized deformations or ripples in the thin plate elements.
How thin plated having initial curvature will affects the structural analysis?
Answer
Initial curvature in a thin plate acts as an initial imperfection, which significantly alters the structural response by inducing bending moments even under purely in-plane loading. This leads to a non-linear load-deflection behavior, where the plate deflects immediately upon loading rather than remaining flat until a critical buckling load is reached, effectively reducing the ultimate load-carrying capacity.
Write short notes on Unsymmetrical bending.
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Define Shear centre? What are the properties of shear centre?
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Sketch the idealized fuselage structural member.
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Discuss about boom area calculation for a rectangular wing under bending loads.
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What do you understand by primary warping?
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Why moment of inertia of boom section is zero?
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Differentiate open and closed section beams.
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What is the minimum and maximum number of spars that can be provided for a wing structure?
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PART - B
Write a note on post buckling behavior of complete and incomplete diagonal tension field beams.
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Derive the general equation for the torsion of a thin-walled beam with suitable example.
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The beam shown in Figure 1 is assumed to have a complete tension field web. If the cross-sectional areas of the flanges and stiffeners are, respectively, 350 mm2 and 300 mm2 and the elastic section modulus of each flange is 750 mm3, determine the maximum stress in a flange and also whether or not the stiffeners will buckle. The thickness of the web is 2 mm and the second moment of area of a stiffener about an axis in the plane of the web is 2000 mm4; E = 70000 N/mm2.
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A plate 10mm thick is subjected to bending moments Mx equal to 10 N-m/mm and My equal to 5 N-m/mm. Calculate the maximum direct stresses in the plate.
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The cross-section of a beam has the dimensions shown in Figure 2. If the beam is subjected to a negative bending moment of 100 k Nm applied in a vertical plane, determine the distribution of direct stress through the depth of the section.
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Determine the position and magnitude of the maximum deflection in the beam of below figure 3.
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Determine the horizontal and vertical components of the tip deflection of the cantilever shown in Figure 4. The second moments of area of its unsymmetrical section are Ixx, Iyy and Ixy.
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What is Wing structural Idealization? Explain the procedure how to idealize a panel using suitable sketches.
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Part of a wing section is in the form of the two-cell box shown in Figure 5 in which the vertical spars are connected to the wing skin through angle sections all having a cross sectional area of 300 mm2. Idealize the section into an arrangement of direct stress carrying booms and shear stress only carrying panels suitable for resisting bending moments in a vertical plane. Position the booms at the spar/skin junctions.
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The thin-walled single cell beam shown in Figure 6 has been idealized into a 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 around the section. Boom areas: B1=B8=200 mm2, B2=B7=250 mm2 B3=B6=400 mm2, B4=B5=100 mm2.
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Express torque for an open section beam subjected to torque load, of any section along the length (figure 7).
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Explain in detail torsion bending constant. Specify the limitations of elementary bending theory.
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Explain the following methods of reducing stress concentration i) Using undercut shoulders ii) Added grooves.
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Derive the equation to find out shear flow in a tapered wing.
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Explain different types of structural members used in aircraft structures.
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Explain different types of fuselage structures. Sketch and explain the cutouts in fuselage structures.
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