Identification of Critical Frequencies by Frequency Analysis of a rotating shaft using Solidworks

Problem Statement: Identification of Critical Frequencies of a rotating shaft by Frequency Analysis using Solidworks.

1. Introduction: A frequency Analysis is basic Dynamic Analysis performed to calculate the inherent Property of system known as natural frequency in which systen vibrate itself without any external forces. We can also get mode shapes which are associated with the behaviour of the system. The Frequency analysis of rotating shaft involves in finding critical Frequencies so as to avoid resonance condition in which the system vibrates with high amplitudes when the system frequency of syatem matches with operating frequencies of a system.
2. Frequency Analysis of Rotating shaft: The frequency analysis of Rotating Shaft involves in below steps.

1. Geometry Creation

2. Material Assignment

3. Boundary Conditions

4. Meshing & Solving

5. Post Processing of results with Comparison

1. Geometry Creation: The Rotating Shaft geometry involves in Sketcing the features in a selected plane with specified dimensions. After the Sketching is done the cross section is extruded to required length as shown in below Figures.

Note: All Dimessiones are in mm.

2. Material Assignment: The material used for 2 Cases of Plate with Hole are Alloy Steel which is having an Yield Strength of 620.42 MPa.

3. Boundary Conditions: The Rotating Shaft having the Stepped Shaft end faces are constrained using bearing support as shown.

4. Meshing & Solution: The Rotating Shaft Model is meshed by selecting Mesh Density as fine. Then the frequency analysis for Rotating Shaft Model are Run for the solution.

5. Post Processing of results: The Rotating Shafts 5 Modes shapes are plotted below

Mode 1: Frequency 0.02 HZ (Rigid Mode)

Mode 2: Frequency 262.78 HZ (Critical Mode in Y Direction)

Mode 3: Frequency 262.82 HZ (Critical Mode in X Direction)

Mode 4: Frequency 413.70 HZ

Mode 5: Frequency 414.18 HZ

Frequencies & Mass Participation Factors:

Conclusion Summary:

1. Mode Shape 1 is a Rigid Body Mode with Frquency close to 0 Hz. This is because of Free Rotation Provided by the bearing support.
2. Mode Shape 2 is Critical Mode in Y Direction with Frequency of 262.78 Hz and Mass participation factor of 0.86248 as shown in above table.
3. Mode Shape 3 is Critical Mode in X Direction with Frequency of 262.82 Hz and Mass participation factor of 0.86249 as shown in above table.
4. Mode 4 is having a frequency of 413.7 Hz which is having Mass participation factors close to zero in all Directions.
5. Mode 5 is having a frequency of 414.18 Hz which is having Mass participation factors close to zero in all Directions.