Design and 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 frequencies are identified as resonant frequencies. This tells us that when a system is designed with the above part, it should avoid operation in these frequencies since failure to do so can lead to devastating failures due to resonance.