Examples on Shrink Fitting and Rotating Disc — Lesson 6

This lesson covers the mechanics of rotating discs, focusing on the calculation of initial shrink fit allowance, contact pressure, and rotational speed. It explains how to solve problems related to rotating discs, using examples of a hub and shaft assembly rotating at 3000 rpm. The lesson also discusses the effects of rotation on the radial and tangential stresses in the disc and shaft. It further explains how to calculate the changes in the inner radius of the disc and the shaft radius due to rotation and contact pressure. The lesson concludes with a discussion on the conditions for a disc to become loose on the shaft and how to calculate the speed at which this occurs.

Video Highlights

02:23 - Explanation of the pressure at the interface and the expansion of the disc and shaft.
06:13 - Calculation of the stress due to rotation and contact pressure.
13:16 - Calculation of the initial interference and the changes in the shaft and disc radius.
32:35 - Explanation of the condition for the disc to become loose on the shaft.
38:59 - Calculation of the speed at which the disc will become loose on the shaft.

Key Takeaways

- The initial shrink fit allowance can be calculated using the given data such as outside diameter, inner diameter, rpm, modulus of elasticity, specific weight, and Poisson’s ratio.
- The contact pressure at the interface of the disc and shaft assembly during rotation can be calculated using the stresses due to rotation and contact pressure.
- The changes in the inner radius of the disc and the shaft radius due to rotation and contact pressure can be calculated using the compatibility condition.
- The speed at which the disc becomes loose on the shaft can be calculated using the initial interference and the changes in the inner radius of the disc and the shaft radius due to rotation.