dabest1
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Hi,
We have an axial fan in the lab that apparently vibrates badly ("wobbles") at certain frequencies.
To find the resonance and the bad frequencies, I decided to do an ANSYS modal analysis.
I am still pretty new to it, and have a few questions.
1) Regardless of how many modes I pick, ANSYS picks certain frequencies. What is the significance of these frequencies?
2) I can't seem to input a rotational velocity into ANSYS. When I add a "Rotational Velocity" Modal, I try to input a 25 rad/s rotation but it does not go through...(I don't get the check mark to its left). So my question is, what is the frequency? Is that equivalent to rotation?
3) So I have just put a fixed point in the center of the fan, and run the analysis. I am getting different colors for the first 3 modes, but the shape seems intact. After mode 4, the entire shape gets ruptured...what does that mean? Let's say all the modes until 150hz had a smooth shape, and the next mode at 300hz is a ruptured shape. Does that mean that the "bad wobbly vibration" happens between 150hz and 300hz?
4) How do i find resonance frequency from these results?
Thanks!
We have an axial fan in the lab that apparently vibrates badly ("wobbles") at certain frequencies.
To find the resonance and the bad frequencies, I decided to do an ANSYS modal analysis.
I am still pretty new to it, and have a few questions.
1) Regardless of how many modes I pick, ANSYS picks certain frequencies. What is the significance of these frequencies?
2) I can't seem to input a rotational velocity into ANSYS. When I add a "Rotational Velocity" Modal, I try to input a 25 rad/s rotation but it does not go through...(I don't get the check mark to its left). So my question is, what is the frequency? Is that equivalent to rotation?
3) So I have just put a fixed point in the center of the fan, and run the analysis. I am getting different colors for the first 3 modes, but the shape seems intact. After mode 4, the entire shape gets ruptured...what does that mean? Let's say all the modes until 150hz had a smooth shape, and the next mode at 300hz is a ruptured shape. Does that mean that the "bad wobbly vibration" happens between 150hz and 300hz?
4) How do i find resonance frequency from these results?
Thanks!