HW8 Hints & Tips

Once again, don't read this until after you have tried working the problems.

HW8.1
The applied torque results in a 1,200,000 N circumferential force at the 75mm radius of the cylindrical surface at the interface.
Dividing this by mu gives the needed 4,800,000 N normal force at that cylindrical surface, which has an area of 35,343 square millimeters.  This P/A gives the interface pressure, which requires a 0.105mm radial interference to create.


HW8.2

The 25 micron radial interference results in an interface pressure of 65.6 MPa.  Given the interface area and coefficient of friction, it would take 68 kN to get it apart.


HW8.3
Thin wall is easy.  Thick wall hoop stress is 246.7 MPa.  Axial is 83.3 MPa.  You know what radial is.


HW8.4
Transmitted torque needs to be 79,577 Nm.  Interface pressure is 263.9 MPa. Radial strain is 0.002626.  Delta T = 434.5°F.

NOTE: The initially given value for transmitted torque was a typo.  The 79,577 Nm is the correct value.