Learning Forum

[mohammedlaminemekhalfia]

Dear Ansys users,

I hope that you are all doing well.

I am studying the vibration of a blade in function of rotational velocity. we suppressed the effect of aerodynamics

I used transient structural, assign the fixed support , Assign a rotational velocity

the blade feedback through ANSYS is presented in the picture.

[Sheldon Imaoka]

It is not clear what you are expecting vs. what you have in the simulation results. When you are comparing 'instantaneous' vs. 'continuous sinusoidal', what are you referencing based on the plot you show? If you are talking about the displacement near time=0 of value 0.25, that is because the rotational velocity is suddenly applied (I'm guessing you step-apply it, which is the default behavior), so it goes from rest to the actual rotational velocity immediately. If you wanted to model the gradual ramp-up, then you should apply rotational velocity by ramping from 0 to final value during a reasonable time interval.
Also, by fixing the blade and applying rotational velocity, you're solving in a rotating frame of reference. Not sure how your measurement is set up, but I'm guessing the laser is stationary, so it's based on a stationary frame of reference.
Regards Sheldon