Frequency Analysis of a rotating shaft

REPORT ON FREQUENCY ANALYSIS OF ROTATING SHAFT

AIM – To conduct the frequency Analysis of rotating shaft and find out the critical frequencies of the shaft from the analysis.

BODY OF THE CONTENT

Frequency analysis

All the components vibrates at its own frequency even if it is not in motion. The frequency at which each component vibrates is known as Natural frequency of that particular component. Each component has its own natural frequency.

The frequency analysis is conducted to find out those natural frequencies of the components. These natural frequencies are need to be considered while designing a complete mechanical system. In case of an assembly the natural frequency of the model and the assembly should not get multiplied so that it will produce an unwanted displacement in the assembly. This particular phenomenon is known as Resonance. If this resonance occurs in actual operating condition it would cause severe damage to the system components. Hence Frequency analysis is very important in such scenario where there are chances of resonance to occur.

The model of the rotating shaft with the dimensions is shown below

Steps to conduct frequency analysis on rotating shaft.

• Create the model of the shaft
• Create the new simulation study of frequency analysis
• Assign a material to the model. In this case the material assigned to the shaft is AISI 1020.
• Apply the bearing fixture at the stepped end of the shaft. Applying this feature fixes to ends of the shaft to replicate actual condition where the two bearings will be placed.
• Generate mesh. Meshing is the process of dividing the model into a small number of elements that helps to compute the required results. Size of the mesh can be varied which can be decided by the coarse and fine sections in the feature. Fine mesh gives more accurate results but takes more time to compute the results as compare to coarse mesh.
• Run the simulation. At this stage the analysis is conducted as per the given constraints to compute the results.

RESULTS

Five mode shapes are been obtained from the results with the values of the resonant frequencies

• Mode 1

The above figure shows the fluctuation of the shaft in y direction at the center of the shaft.

• Mode 2

The above figure shows the fluctuation of the shaft in z direction at the center of the shaft.

• Mode 3

The above figure shows the fluctuation along the circumference of the disc at the center of the shaft.

• Mode 4

The above figure shows the momentary fluctuation of the disc along the y plane.

• Mode 5

The above figure shows the momentary fluctuation of the disc along the z plane.

Resonant frequency at all modes

Modes	Frequency (rad/sec)	Frequency (Hertz)
Mode 1	4013.8	638.82
Mode 2	4015.9	639.15
Mode 3	6233.7	992.13
Mode 4	11817	1880.7
Mode 5	11819	1881.1

CONCLUSION = From the entire challenge it can be concluded that frequency analysis can help to design the system more efficiently in case where there is a chances of resonance to occur.