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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.