Frequency Analysis of a rotating shaft

Aim: To conduct Frequency analysis over the given CAD model.

Theory: Frequency, in physics, the number of waves that pass a fixed point in unit time; also, the number of cycles or vibrations undergone during one unit of time by a body in periodic motion. A body in periodic motion is said to have undergone one cycle or one vibration after passing through a series of events or positions and returning to its original state.

Frequency is defined as the number of oscillations of a wave per unit time being measured in hertz(Hz). The frequency is directly proportional to the pitch. Humans can hear sounds with frequencies ranging between 20 – 20000 Hz. Sounds with frequencies over the human ears range are known as ultrasound and sounds with frequencies less than the audible range is known as infra sound.

The wave speed (v) is defined as the distance travelled by a wave per unit time. If considered that the wave travels a distance of one wavelength in one period,

ν=λ/T

As we know that T = 1/f, hence we can express the above equation as,

V = f λ

Formula used:

Model:

Part Design

Part Drawing

Procedure:

1. In this problem we will first start modelling of part in SOLIDWORKS part modelling and then we will go for SOLIDWORKS simulation.
2. We will do using two different materials with five node shapes in frequency analysis.
3. Now we will start sketching of the model in which we will first make the small circle and then we will extrude it using the mid plane option.
4. Now we will make bigger circle using the front plane and again we will use the extrude option using the mid plane.
5. Now we will select the face of the smaller circle end of up to which it is extruded and then we will again make a smaller circle and then we will extrude it to a smaller range.
6. Now we will mirror the smaller circle we made and then mirror through the front plane and then we will hit ok which will create the cylinder on the other end.
7. Now we are done with part modelling and then we will go for SOLIDWORKS simulation.
8. Now we will go for frequency analysis and then we will name the case.
9. Now we will go to part and then for the first case we will add alloy steel and for the second case we will take plain carbon steel.
10. Now we will mesh the part and then we will take the automatically generated mesh and then we will apply fixtures at the both steep faces.
11. We will be taking bearing fixtures at both the steeper ends and then we will one by one select the steep faces.
12. Now defining of boundary condition is done we will now go to run the study.
13. Now we will get our required results at different frequencies.
14. We will also do analysis using the plain carbon steel and then we can compare the both.

Results and Plots:

Using Alloy Steel

Case 1:

Case 2:

Case 3:

Case 4:

Case 5:

Resonant Frequencies

Mass Participation

Result Comparison

Report

Using Plain Carbon Steel

Case 1:

Case 2:

Case 3:

Case 4:

Case 5:

Resonant Frequencies

Mass Participation

Result Comparison

Report

Conclusion:

• From the above we can conclude that as the frequency will increase time period will reduce.
• Amplitude in case of Alloy steel is more than Plain carbon steel
• Hence, we can conclude that Plain carbon steel is better than Alloy steel.
• We can also take other materials to compare other materials and to select the best one.