Problem 264
A steel rod 3 feet long with a cross-sectional area of 0.25 in.2is stretched between two fixed
points. The tensile force is 1200 lb at 40°F. UsingE= 29 × 106psi andα= 6.5 × 10-6in./(in.·°F),
calculate
(a) the temperature at which the stress in the bar will be 10 ksi
T= 12.41 °F
(b) the temperature at which the stress will be zero.
Tf = 65.46 °F
Problem 265
A bronze bar 3 m long with a cross sectional area of 320 mm2is placed between two rigid
walls as shown in Fig. P-265. At a temperature of -20°C, the gap Δ = 2.5 mm. Find the
temperature at which the compressive stress in the bar will be 35 MPa. Useα= 18.0 × 10-
6m/(m·°C) and E = 80 GPa.
Answer:
Problem 267
At a temperature of 80°C, a steel tire 12 mm thick and 90 mm wide that is to be shrunk onto a
locomotive driving wheel 2 m in diameter just fits over the wheel, which is at a temperature of
25°C. Determine the contact pressure between the tire and wheel after the assembly cools to
25°C. Neglect the deformation of the wheel caused by the pressure of the tire. Assumeα=
11.7μm/(m·°C) and E = 200 GPa.
Answer:
Problem 268
The rigid bar ABC in Fig. P-268 is pinned at B and attached to the two vertical rods. Initially,
the bar is horizontal and the vertical rods are stress-free. Determine the stress in the
aluminum rod if the temperature of the steel rod is decreased by 40°C. Neglect the weight of
bar ABC.
Answer:
Problem 269
As shown in Fig. P-269, there is a gap between the aluminum bar and the rigid slab that is
supported by two copper bars. At 10°C, Δ = 0.18 mm. Neglecting the mass of the slab, calculate
the stress in each rod when the temperature in the assembly is increased to 95°C. For each
