Frequency Analysis of a rotating shaft

Aim: Design and Frequency analysis of a rotating shaft.

Main Objective:

To create a solid model of a rotating flywheel on a shaft and identify 5 critical frequencies by generating 5 mode shapes using Solidworks Simulations Frequency analysis feature.

Figure 01: Dimensions of the solid model

Tools used:

Solidworks Simulation module

Prerequisite:

A flywheel on a shaft modeled in Solidworks using the Solid modeling tools.

Boundary conditions:

Part type = Shaft with mounted flywheel

Material = Alloy Steel (See figure 4 for Material properties)

Fixtures = 2X bearing supports on either side of the shaft

Tensile load = 120 rad/s Centrifugal force (Assumption)

Mesh size = 6 mm

No. of frequencies = 5

Incompatible bonding options = Automatic

Solver selection = Automatic (FFEPlus / Direct Sparse solver)

Material Properties: of Alloy Steel

Figure 03:Solid Model of the flywheel on the shaft with bearing fixtures and direction of the centrifugal force

Analysis Results:

After applying the boundary conditions, the following modes were identified by the simulation

Mode 01: Deformation at a frequency of 19.078 Hz

Mode 02: Deformation at a frequency of 335.78 Hz

Mode 03: Deformation at a frequency of 335.82 Hz

Mode 04: Deformation at a frequency of 1031 Hz

Mode 05: Deformation at a frequency of 1031.4 Hz

The following are the resonant frequencies identified by the simulation for the 5 modes.

Mode Frequency (Radian/Sec) Frequency (Hertz) Period (Seconds)

1 119.87 19.078 0.05241600

2 2109.8 335.780 0.00297820

3 2110.0 335.820 0.00297780

4 6478 1031.000 0.0009993

5 6480.3 1031.400 0.00096959

Observations:

The 5 waves are identified as smooth frequencies. This tells us that if the system is built with the above components, it should avoid operating at these limits because failure to do so could lead to malfunction due to resonance.