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MECHANICS OF MATERIALS QUIZ I (84313) CURTISS-WRIGHT ENGINEERING

Course B-4 Seely: Arts. 1-28 CADETTES 11D-UH1-118

l. (a) Determine the axial stress which will be developed in a streamline aluminum

alloy tubing strut due to a temperature drop of 60° [degrees] F if there is no change

in length of the strut. The length of the strut is 30 in.; its cross-sectional

area is 0.106 sq. in., and the coefficient of thermal expansion of

aluminum is 0.000012 per degree F. The modulus of elasticity of aluminum

alloys is 10,000,000 p.s.i.

(b) At a point on the surface of a propeller shaft of an airplane in a climb

are horizontal tensile stresses of 12,000 p.s.i. and vertical compressive

stresses of 2000 p.s.i. Determine the stresses which act on a plane at the

point making an angle of 30° [degrees] with the horizontal.

2. (a) A cylindrical compressed air tank is 20 in. in diameter is made of 1/8 in.

plates. Determine the maximum tensile stress in the plate if the internal

pressure is 100 p.s.i.

(b) A 2" x 2" x 1/8" angle is to be welded to a gusset plate in a truss construction

The angle carries a stress of 20,000 p.s.i. and the weld will transmit 1000

lb. per inch. Design the connection so that there will be no bending at

the joint and so that the length of welds on the sides of the angle shall be

as small as possible. The cross sectional area of the angle is 0.48 sq. in.

and its centroidal axis is located 0.55 in. from the back of the angle.

3. A hollow steel propeller shaft transmits 685 H.P. when turning over at

1800 r.p.m. The outer diameter is 4 in. and the inner diameter 2 in. Es

for steel is 12,000,000 p.s.i.

(a) Determine the maximum shearing unit stress in the shaft.

(b) Determine the angle of twist in a 1 ft. length of the shaft.

4.Two 0.102-in. plates are to be connected by a double riveted butt joint

with two cover plates. The pitch of the rivets in the inner row is 1 in.

and in the outer row 3 in. The rivets are 1/4" in diameter. Using a 3-in.

length of joint, determine the efficiency. The following unit stresses are

not to be exceeded. Fbr = 30,000 p.s.i., Fs = 10,000 p.s.i.; Ft = 15,000 p.s.i.

Tension in the coverplates may be neglected.

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