=
For all questions take ESTREL =200 GPa, STEEL = 12 x 10 /°C; EBRASS
BRASS 15 x 10 /°C; EALUMINIUM = 70 GPa, ALUMINIUM = 22 x 10°/°C;
ECOPPER 110 GPa, & COPPER = 17 x 10°/°C.
1.
100 GPa,
A copper bar of diameter 80 mm and length 120 mm is being turned between centres on
a lathe. The heat generated during cutting causes the bar temperature to rise by 8°C. The
resulting expansion of the bar is partially restricted by the tailstock which exerts a
constant restraining force of 30 kN on the workpiece. Calculate the operational length
of the bar.
[120,0098 mm ]
2.
3.
4.
5.
A stepped steel bar has a diameter of 60 mm for the first 200 mm of its length and the
remaining 100 mm has a diameter of 40 mm. It is heated from 15°C to 70°C, then
rigidly clamped at both ends and then cooled back to 15°C. Calculate the maximum
stress in the bar.
[210 MPa T]
An aluminium rod 10 mm in diameter and 40 mm long is joined to the end of a steel rod
5 mm in diameter and 50 mm long. The composite rod is then heated through 100°C.
(a) Calculate the total increase in length of the composite rod.
(b) If the composite rod was allowed to expand an amount of only 0,1 mm during this
temperature change, what stresses would be set up in the steel and aluminium.
(c) Calculate for (b), the final position of the junction between the two materials after
the change in temperature.
[0,148 mm; 122,2 MPa C; 30,55 MPa C; 40,0705 mm ]
A steel rod 40 mm in diameter and 250 mm long is heated through 80°C and at the same
time subjected to an axial tensile force. If the total extension of the rod is to be 0,4 mm
what should be the magnitude of the pulling force.
[161 kN]
A steel rod 30 mm diameter is placed inside, and concentric with, a bronze tube 35 mm
inside and 45 mm outside diameter. The tube and rods are rigidly brazed together at the
ends to form a compound bar 500 mm long. When the temperature of the compound bar
is raised through 40°C its increase in length is found to be 0,2645 mm. Calculate (a) the
stress in the steel, (b) the stress in the bronze, and (c) the coefficient of linear expansion
for bronze given EBRONZE = 100 GPa.
19,8 MPa T, 11 MPa C, 16 x 10*]
