Static analysis Adams model from Fast

Wind & Water Structural Analysis
1

Dear Jason,
I am doing many analyses with the Adams model that I obtained from FASTv.7 with the flexible tower.
In these analyses I exported the tower top acceleration of the tower with a “measure” ACCZ(…) when the rotor is free ( I deleted the Hss Motion).
But even if the wind has always 0 velocity when I export the tower top acceleration time history I see a “peak” at the beginning. This is for sure due to the gravity, that is not zero. I want to start a dynamic simulation without seeing this effect. Usually this can be done in Adams using a Static Analysis before the Dynamic Analysis. Is it possibile to do this in the Adams model generated from fast?
The “Deafult” acf generated from Fast is like this:

anemos_ADAMS
anemos_ADAMS
INTEGRATOR/GSTIFF, ERROR = 0.001, HMAX = 1.000000E-03, INTERPOLATE = ON
SIMULATE/DYNAMICS, END = 1.000000E-03, DTOUT = 1.000000E-03
DEACTIVATE/JOINT, RANGE = 1301, 1399
DEACTIVATE/JOINT, ID = 1500
SIMULATE/DYNAMICS, END = 1.000000E+01, DTOUT = 1.000000E-03
STOP

I have tried to change it this way :

anemos_ADAMS
anemos_ADAMS
INTEGRATOR/GSTIFF, ERROR = 0.001, HMAX = 1.000000E-03, INTERPOLATE = ON
DEACTIVATE/JOINT, RANGE = 1301, 1399
DEACTIVATE/JOINT, ID = 1500
SIMULATE/STATIC
SIMULATE/DYNAMICS, END = 4.000000E+00, DTOUT = 1.000000E-03
STOP

But I always have an error !!

Can you hel me?

2

Dear Alessandro,

I have not used MSC.ADAMS in years, so, I’m not really sure I can answer your question.

I know that the approach we implemented in the ADAMS Control file (*.acf) to simulate one time step with all degrees of freedom disabled was very useful to minimize start-up transients. I can’t see that eliminating that step would help, at least if the rotor is given an initial rotor speed. (Perhaps your approach would be useful if the initial rotor speed is zero?)

Regardless, I’m not sure what you mean when you say that you “see a “peak” at the beginning”. Are you concerned that this “peak” is causing a problem after the start-up transients decay away? (Normally we always neglect simulation start-up transients from post-processing for loads etc.; I would normally not be concerned with what the start-up transient entails as long as its effect on the response of interest is negligible.)

Best regards,