Frequency analysis of a rotating shaft
INTRODUCTION
Vibration is a really annoying problem in most of the machinery, structures as well as automotive systems. If not controlled properly it will cause unexpected failures and instabilities in the system due to resonance. IF the excitation frequency of the system matches the natural frequency of the system, it will cause resonance to occur. The project aims to find out the natural frequencies of a system of rotating the shaft with a flywheel.
Project Objective:
The project aims to find out the natural frequency of a rotating shaft. This will yield the safe operating condition of the system without causing resonance. The first five mode shapes and natural frequencies were found out.
Boundary Conditions
A 5mm mesh was used to model the rotating shaft with alloy steel as a material. Both stepped faces at the end were fixed using bearing fixture. This will arrest all the translations and rotations except the translation of the nodes along the axis of the bearing.
Figure 1Boundary conditions
Results:
Figure 2 Mode shape 1
Figure 3 Mode shape 2
Figure 4 Mode shape 3
Figure5 Mode shape 4
Figure 6 Mode shape 5
Failure speeds causing resonance
|
Frequency(Rad/sec) |
Frequency(Hertz) |
Period(Seconds) |
RPM |
|
0.28124 |
0.044762 |
22.341 |
2.685644 |
|
1350 |
214.86 |
0.0046543 |
12891.55 |
|
1350.1 |
214.88 |
0.0046537 |
12892.51 |
|
4743.7 |
754.98 |
0.0013245 |
45299 |
|
4744.3 |
755.08 |
0.0013244 |
45304.73 |
Conclusion
From the analysis conducted, the first five mode shapes of the rotating shaft were analysed and the rpm corresponding to the failure is calculated. The operating speed should not be around the listed rpm for satisfactory performance.
Submitted by,
Amal Swalih SR