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Unformatted text preview: Homework 3 Due 1/25/2012 •
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• Read chapter 2, sections 2.1 2.3, 2.5 Work must be completed on engineering paper. Show all work. Draw pictures, where appropriate, to illustrate complex answers. Make sure your work is neat, legible, and professionally done. Problem 1 A nose gear strut for the landing gear of a private airplane (STOL CH 701) is subjected to compressive loads during landing. The loads are predicted to be high. Because the strut is crucial and failure could lead to a loss of life, the strut is to be designed with a factor of safety of 4 (that is, designed so that the strut is capable of supporting loads four times as great as expected). Based on readily available material properties, select a material and design the support strut, and justify your answer with appropriate calculations (provide drawings with labeled dimensions, weight of design, and justifications that strut will support load based on material properties and dimensions). Specifications for the aircraft are given below. strut 1 SPECIFICATIONS STOL CH 701 WING SPAN WING AREA LENGTH HEIGHT (rudder tip) EMPTY WEIGHT GROSS WEIGHT USEFUL LOAD WING LOADING POWER LOADING DESIGN LOAD FACTOR (ultimate) CABIN WIDTH (shoulders) CABIN WIDTH (optional bubble doors) FUEL CAPACITY (std., dual wing tanks) 27 FEET 122 SQ.FT. 20 Ft. 11 In. 8 Ft. 7 In. 580 LBS. 1,100 LBS. 520 LBS. 9.0 LBS/FT² 13.75 LBS/BHP +6 G /  3G 40 INCHES 44 INCHES 20 US Gallons 8.2 m. 11.4 m.sq. 6.38 m. 2.6 m. 263 kg. 500 kg. 236 kg. 43.8 m² 6.25 kg/BHP 100 cm. 110 cm. 76 liters 2 Problem 2 The hydraulic cylinder CF, which partially controls the position of rod DE, has
been locked in the position shown. Link AB has a uniform rectangular cross
section of 12 x 25 mm and is connected at B to member BD by an 8mm
diameter pin. Knowing that the maximum allowable average shearing stress in
the pin is 140 MPa, determine (a) the largest force P which may be applied at E
when the angle theta is 60 degrees, (b) the corresponding bearing stress at B in
the link AB, (c) the corresponding maximum value of the normal stress in link
AB. Problem 3 A tension test was performed on a steel specimen having an original diameter of 0.503 in. and a gauge length of 2.00 in. The data is listed in the table. Plot the stress–strain diagram and determine approximately the modulus of elasticity, the ultimate stress, and the rupture stress. IF DRAWING BY HAND: Use a scale of 1 in. = 15 ksi and 1 in. = 0.5 in./in. Redraw the linear elastic region, using the same stress scale but a strain scale of 1 in. = 0.001 in. Load (kip) 0 2.5 6.5 8.5 9.2 9.8 12.0 14.0 14.5 14.0 13.2 Elongation (in.) 0 0.0009 0.0025 0.0040 0.0065 0.0098 0.0400 0.1200 0.2500 0.3500 0.4700 Problem 4 The pole is supported by a pin at C and an A 36 steel guy wire AB. If the wire has a diameter of 0.2 in., determine how much it stretches when a horizontal force of 2.5 kip acts on the pole. 3 Problem 5 The σ − ε diagram for a collagen fiber bundle from which a human tendon is composed is shown. If a segment of the Achilles tendon at A has a length of 6.5 in. and an approximate cross sectional area of 0.229 in.2, determine its elongation if the foot supports a load of 125 lb, which causes a tension in the tendon of 343.75 lb. Problem 6 Two gage marks are placed exactly 10 in. apart on a 0.5 in. diameter aluminum rod with E=10.1 x 106 psi and an ultimate strength of 16 ksi. Knowing that the distance between gage marks is 10.009 in. after a load is applied, determine (a) the stress in the rod, (b) the factor of safety. 4 ...
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 Spring '08
 DICKRELL

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