Frequency Analysis of a rotating shaft

AIM:

Frequency analysis of a rotating shaft and finding out 5 mode shapes and listing the resonant frequencies.

THEORY:

With Solidworks Simulation you can create a Frequency Study and evaluate the model, the natural vibration modes of your design and compare them to the frequency generated by the machine or equipment in use.

The frequency study settings are easy and straight forward as always the case with SolidWorks.

We need to set the number of natural modes required (usually the first 5 modes are required). This can be set from the study properties and the frequency options tab. In this case, I want the first five modes.

Now it is all ready to go, just hit run and check the results. So, what are the outputs of this study and how can we benefit from these results. Under the results folder, we will find 5 plots representing the 5 modes we requested in the study properties. The 5 plots show the behaviour of the model in each mode.

The amplitude value here is meaningless and only to be used in the comparison across different modes.

Then it is time now to see if one of these modes excites in the equipment operating frequencies range. To do so you just need to select the result folder right mouse click and list frequency results.

Now based on this result it is easy to make the decision whether or not this design will be fit for purpose.

PROCEDURE:

1.First design the solid body with proper dimensions.

2. Switch to simulation then go to frequency study and add the default material.

3. Make bearing fixture on the stepped face of the rod at the two ends.

4. Mesh with 6mm edge length.

5. Then set the number of natural modes required (usually the first 5 modes are required).

6. Run the above study and obtained the plots as below:

OBSERVATION:

1. The shaft has to designed and used in operations where it cannot meet the above frequencies which result in failure of the shaft due to resonance phenomenon.