A pulley will spin at 36,000 RPM. You need to check to see if a resonance condition could occur.
The pulley is a structural steel part (Geometry file - ParaSolid, available). The inside wall of the hole can be treated as a fixed support.
What frequency corresponds to the 36,000 RPM angular velocity ?
Does the spinning of this body at a constant RPM speed have any effect on the natural frequencies ?
What natural frequencies do you observe for this part (modes 1 - 6) ?
Describe the mode shape of mode 3 (below).
Referring to the picture of mode 3 below, how can a part with a diameter of ~140 mm. exhibit a maximum deflection of 59.2 mm. ?
Is resonance likely to be a problem for this part ?
ANSWERS:
What frequency corresponds to the 36,000 RPM
angular velocity ?
36000 RPM is 600 Hz
Does the spinning of this body at a
constant RPM speed have any effect on the natural frequencies ?
YES - prestressed modal analysis shows the lowest natural
frequency increases ~15-16 % from the centrifugal force and stress.
What natural frequencies do you observe for this part (modes 1 - 6) ?
| Mode | Freq. (Hz) |
| 1 | 1328 |
| 2 | 1329 |
| 3 | 1442 |
| 4 | 1901 |
| 5 | 1901 |
| 6 | 3846 |
Describe the mode shape of mode 3.
"umbrella" shape [zero nodal diameters]
Referring to the picture of mode 3, how can a
part with a diameter of ~140 mm. exhibit a maximum deflection of 59.2 mm.
?
In modal analysis, displacements are
"normalized," not real values - useful only to show the mode shape
images.
Is resonance likely to be a problem for this
part ?
NO, the lowest natural
frequency is 1328 Hz and the driving frequency is 600 Hz