TABLE OF CONTENTS Parts are often assembled by heating the outer member and thus expanding it, while simultaneously, if necessary, cooling the inner member and shrinking it. This puts the outer member in tension and the inner member in compression.
Q:
A 1.00 m cast-iron wheel has a 1.00 mm thick steel ring shrunk onto it as a tire. The interference fit is 0.1000 mm. What is the stress in the ring? What is the contact pressure?
Answers
Q:
The diametral strain is 0.100/1,000 = 0.000100 m/m. The circumferential strain would be the same, though the circumferential elongation would equal ? times diametral elongation.
Stress = E ? ? = 2.1 10 11 100 10 -6 = 21.0 MPa stress in the ring.
Hoop stress ? = PD/2t so P = 2t ?/D = 2 0.001 21.0 10 6/1.0 = 42,000 Pa
The contact pressure would thus equal 42.0 kPa
N.B. It is assumed that the cast iron wheel does not shrink since the ring is very thin in comparison, and would exert minimal force on the wheel.
Q:
A steel liner is assembled in an aluminum pump housing by heating the housing and cooling the liner in dry ice. At 20 C before assembly, the liner outside diameter is 8.910 cm and the housing inside diameter is 8.890 cm. After assembly and inspection, several units were rejected because of poor liners. It is...
