I use ANSYS for rotor dynamics analysis.
I gave rotational speed 5rad/sec.
modal freqencies are 15.021, 15.036, 36, 78, 411Hz.
my question is that when i simulate and represent data in terms of deformation the frequency I get always 20 Hz. why is it so?
it should be 5Hz as input.
Dear Tarun,
I am not sure whether you are doing transient or steady-state analysis. If the shaft is rotating at a constant speed 5Hz, then you are looking at steady state. Unless, you have some other initial conditions, which will provoke the transient behavior. It is not clear as to what initial conditions you assumed, if any.
On the issue of why not the input speed of 5Hz is not showing in the response, one must recall that this is a rotation speed. However, I assume you are plotting the time response of transverse deflection (bending), which is not directly related to the rotational. The rotational speed affects the bending deformation through stiffening as well as Coriolis effects. This 5Hz can appear as the rigid body carrier frequency if you are plotting the time response of the torsional vibrations, but not the transverse deformation.
Sir Yehia A. Khulief ,
I want to produce Synchronous Vibration in Jeffcott Rotor Model using ANSYS.
Is it done in Transient or static mode?
Actually any rotational speeds end with sub-synchronous vibration.
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