Frequency Analysis of a rotating shaft

Frequency Analysis of a rotating shaft

AIM:

1. To find out the critical frequencies of a rotating shaft in Solidworks.
2. To create the model in Solidworks according to dimensions that you see fit.
3. Model it in Solidworks according to the image shown.
4. To conduct a frequency analysis and apply a bearing fixture on the stepped face of the rod at the two ends and perform the analysis.
5. To find out 5 mode shapes and list the resonant frequencies.

OBJECTIVE:

In this study, we will do the frequency analysis on the rotating shaft. It is important to find the natural frequency because if the rotating shaft frequency matched with the natural frequency then a large amplitude displacement will occur thus the shaft gets distorted. So we will find the natural frequency and find the different mode shapes and listing the resonant frequencies.

INTRODUCTION:

Natural frequency: The frequency at which a system oscillates when not subjected to a continuous or repeated external force.

Forced vibrations and resonance: Forced vibrations occur when the object is forced to vibrate at a particular frequency by a periodic input of force. If an object is being forced to vibrate at its natural frequency, resonance will occur and large amplitude vibrations can be observed.

Mode shapes of vibration: A mode shape is a specific pattern of vibration executed by a mechanical system at a specific frequency. Different mode shapes will be associated with different frequencies. The experimental technique of modal analysis discovers these mode shapes and the frequencies.

Natural frequencies and modal shapes depend on:

• Geometry
• Material properties and mass
• Support conditions (fixtures)
• In-plane loads

PROCEDURE:

Create a 2D sketch with appropriate dimensions.

Using revolve, to create a 360-degree revolve of the 2D sketch into a 3D model.

Now enter Simulation-> New study -> Frequency analysis

FREQUENCY ANALYSIS:

In frequency analysis Right-click on the part -> Apply material ->Alloy Steel material(Default)

Then right-click on fixtures -> Bearing fixtures -> select stepped face of the rod at the two ends.

Now create the standard mesh of the model.

MESH DETAILS:

Mesh type - Solid mesh

Element size - 6 mm

Mesh quality - High

Total nodes -33025

Total Elements - 20560

Then click mesh and run.

RESULTS:

Mode 1:

Mode 2:

Mode 3:

Mode 4:

Mode 5:

FREQUENCY AT EACH MODE: