Dear reader
Hello and greetings
I’m currently trying to apply simple TMD controller on tower in #Test18(5Mw onshore) by FAST.V8. i simply changed CompTTMD in “NRELOffshrBsline5MW_Onshore_ServoDyn.dat” file to “True” and TMD_CMODE in “NRELOffshrBsline5MW_ServoDyn_TMD.dat” to “1” in order to using semi-active control. After running this test i encounter no changes in “TTDspFA” ,“TTDspSS” which are related to tower top transitional deflection. at first step i just want to know how can i simply apply TMD in order to control tower top transitional deflection?
Thank you in advance
Dear @Mohammad.Mojtahed,
Are you getting outputs that you expect from the TMD module of FAST v8?
Best regards,
Dear @Jason.Jonkman
As i mentioned there is NO difference between “TTDspFA” value in case of using TMD file (NRELOffshrBsline5MW_ServoDyn_TMD.dat) and in case of NOT using it (CompTTMD= false). So the answer for your question definitely would be NO.
Best regards,
Dear @Mohammad.Mojtahed,
I meant what do the TMD outputs look like, e.g., TTMD_XQ and TTMD_YQ?
Best regards,
Dear @Jason.Jonkman
I think problem solved;
Because i thought when you’re applying TMD it will implement the effect on “TTDspFA” value by itself;
By this question you mean the new displacement of Tower-top would be got value in TTMD_XQ and TTMD_YQ?
Best regards,
Dear @Jason.Jonkman
Actually i realized TTMD_XQ and TTMD_YQ outputs are related to TMDs displacement itself and there has nothing to do with Top-towers displacement. so problem is still going on and when i’m applying TMD there is no difference between TTDspFA values in case of NOT using it. Logically When we apply TMD we should see a large amount of differences in Top-tower displacement because it has been controlled by TMD 
To be clear for your question, i’m just monitoring the “TTDspFA” output.
Best regards,
Dear @Mohammad.Mojtahed.
I’m suggesting that you look at TMD outputs TTMD_XQ and TTMD_YQ to verify that they are working as expected.
Best regards,
Dear @Jason.Jonkman
No actually I’ve realized even “TTDspFA” output without controlling is not as expected. i have modeled NREL 5MW onshore with Fast V7 and “TTDspFa” output should be like sinusoidal diagram. true results has been attached further.
But by modeling 5Mw onshore in FastV8 and monitoring the results you can encounter this outputs for “TTDspFa”.
So, back to the first, what’s your suggestion for this problem ?
Best regards,
Dear @Mohammad.Mojtahed,
In both of your plots, it looks like you have a sizeable start-up transient (initial condition solution that fades away over time), which can be minimized by choosing better initial conditions. Regardless, it useful to neglect the start-up transient when post-processing simulation results.
My point about looking at the TMD outputs is to verify that the TMD is actually enabled and producing reasonable results.
Best regards,