making sense of flow induced vibration results
making sense of flow induced vibration results
(OP)
I have a set of amplitude plots of flow induced vibrations and was wondering if anyone could help me understand a few points. I know that attenuation of amplitudes indicate numerical damping, and increase in the amplitude of vibrations is a sign of instability. But what if:
1) before any of this happens, the code stops and crashes, i.e. going from stable waves with similar amplitudes to the code not converging and crashing? Does anyone know what that indicates?
2) the amplitude peaks increase at some time steps and reduce at other time steps?
3) what do non-smooth waves (in particular at the peaks) indicate? Thanks you in advance!
1) before any of this happens, the code stops and crashes, i.e. going from stable waves with similar amplitudes to the code not converging and crashing? Does anyone know what that indicates?
2) the amplitude peaks increase at some time steps and reduce at other time steps?
3) what do non-smooth waves (in particular at the peaks) indicate? Thanks you in advance!





RE: making sense of flow induced vibration results
Are your plots coming from measurements of a machine, or are they outputs from FEA software?
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JHG
RE: making sense of flow induced vibration results
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RE: making sense of flow induced vibration results
RE: making sense of flow induced vibration results
I have written code modelling vibrations. I have observed non-converging results generally because I coded something wrong. As I recall, I input all the forces from my free body diagram, including force of inertia. When I removed the force of inertia, it all worked. Your mass accelerates due to damping and spring force.
--
JHG
RE: making sense of flow induced vibration results
TTFN
I can do absolutely anything. I'm an expert!
homework forum: //www.engineering.com/AskForum/aff/32.aspx
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