Frequency Analysis of a rotating shaft

INTRODUCTION - ROTATING SHAFT:

Rotating shaft - a revolving rod that transmits power or motion. The camshaft has cams attached to it. Crankshaft - a rotating shaft driven by a crank. Driveshaft - a rotating shaft that transmits power from the engine to the point of application.

AIM:

To perform the Frequency analysis by creating a model provided to find out 5 mode shapes using simulation in Solidworks.

OBJECTIVE:

• To find out the critical frequencies of a rotating shaft in Solidworks.
• To find out 5 mode shapes of the shaft and to list out the resonant frequencies.

PROCEDURE:

To create a model of a rotating shaft in Solidworks. The dimensions used are as follows:

Smaller Shaft Diameter = 50mm

Extrude = 1000mm (from midplane)

Shaft Diameter = 80mm

Extrude = 900mm (from midplane)

Rotating Shaft diameter = 300mm

Extrude = 25mm (from midplane)

To perform the Frequency Analysis on the rotating shaft, enter the simulation tab with frequency study.

Here, Alloy material is provided as the material for the rotating shaft.

Apply a bearing fixture on the stepped face at the two ends of the rotating shaft.

Now create a mesh and run the frequency analysis study to get the different mode shapes of the shaft.

Save the results and find out the 5 mode shapes of the shaft and listing the resonant frequency.

MATERIAL PROPERTIES:

Model Reference	Properties
	Name: Alloy Steel Model type: Linear Elastic Isotropic Default failure criterion: Max von Mises Stress Yield strength: 6.20422e+008 N/m^2 Tensile strength: 7.23826e+008 N/m^2 Mass density: 7700 kg/m^3 Elastic modulus: 2.1e+011 N/m^2 Poisson's ratio: 0.28 Thermal expansion coefficient: 1.3e-005 /Kelvin

CONNECTOR DEFINITIONS:

BEARING CONNECTOR:

Model Reference	Connector Details
Bearing Support-1	Entities: 1 face(s) Type: Bearing

Bearing Support-2

Entities: 1 face(s) Type: Bearing

MESH DETAILS:

Mesh type	Solid Mesh
Mesher Used:	Standard mesh
Automatic Transition:	Off
Include Mesh Auto Loops:	Off
Jacobian points	4 Points
Element Size	18.5324 mm
Tolerance	0.92662 mm
Mesh Quality Plot	High

RESULTS:

FREQUENCY STUDY RESULTS:

Name	Type	Min	Max
Amplitude1	AMPRES: Resultant Amplitude Plot for Mode Shape: 1(Value = 0 Hz)	0.001 Node: 4588	0.352 Node: 8092

Name	Type	Mint	Max
Amplitude2	AMPRES: Resultant Amplitude Plot for Mode Shape: 2(Value = 140.385 Hz)	0.000 Node: 2359	0.180 Node: 2569

Name	Type	Min	Max
Amplitude3	AMPRES: Resultant Amplitude Plot for Mode Shape: 3(Value = 140.392 Hz)	0.001 Node: 2359	0.180 Node: 3866

Name	Type	Min	Max
Amplitude4	AMPRES: Resultant Amplitude Plot for Mode Shape: 4(Value = 631.729 Hz)	0.000 Node: 2568	0.287 Node: 811

Name	Type	Min	Max
Amplitude5	AMPRES: Resultant Amplitude Plot for Mode Shape: 5(Value = 631.792 Hz)	0.000 Node: 2122	0.287 Node: 331

MODE LIST:

Frequency Number	Rad/sec	Hertz	Seconds
1	0	0	1e+032
2	882.07	140.39	0.0071233
3	882.11	140.39	0.0071229
4	3969.3	631.73	0.001583
5	3969.7	631.79	0.0015828

CONCLUSION:

The frequency analysis is performed on the rotating shaft and the different mode shapes of the rotating shaft is been listed above. Thus the following are observed after viewing the results of the frequency analysis on the rotating shaft:

• When the shaft vibrates at 140.39 Hz or 631.79 Hz, it would damage the shaft.
• It is suggested to operate the rotating shaft such that it does not reach the above-mentioned frequencies to prevent the shaft from damage.
• By doing so, it reduces the damage to the shaft and hence it provides the increase in life period to the rotating shaft.

Thus the frequency study is been performed to find out the different mode shapes of the shaft using the simulation in SolidWorks.