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# midterm09 - 2 ft center-to-center The plate is fastened to...

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AUBURN UNIVERSITY Department of Civil Engineering CIVL 7690 Analysis of Plate and Shell Systems Midterm Exam, Take Home, Due July 2, 2009 1. Consider the plane stress problem shown in the sketch. Find the stresses at the boundaries of the plate element, ABCD, and the movement of the block under the action of the load W. Also, evaluate the stress function. Neglect friction, if any, at the boundaries. The vertical edges, AB and CD, of the plate element maintain contact with the immovable rigid boundary wall through a thin film of lubricant. 2. An aircraft wing skin is made of super aluminum alloy thin plate. The structural model of this wing skin may be considered as an infinitely long plate resting on rib stiffeners spaced at
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Unformatted text preview: 2 ft. center-to-center. The plate is fastened to the ribs using ¼” diameter rivets, d b , which may be considered as pinned supports (not roller supports). The skin is subjected to 300MPH equivalent air pressure acting normal to the plate. The basic wind pressure may be obtained using p=0.00256 v 2 where p=basic wind pressure in pound-force per square foot, v=wind speed in miles per hour. (a) Determine the plate thickness, t. (b) Determine the rivet spacing considering only the bearing capacity, p brg =1.5U p d b t. E=10x10 3 ksi, 24ksi, 12ksi (allowable), =0.3, 1.5 y b t p y σ μ = = = = A A 0.25" D C B W=500 lbs 2.5" d = 2" b = A Rigid block 6 =0.2 E=3 10 psi × Section A-A W y x...
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