FAST theory manual

Wind & Water Computer-Aided Engineering Software Tools
101

Dear Dr Jonkman,

Could you please send me the “Unofficial FAST Theory Manual” as well?

fanzhong.meng12@googlemail.com

Thank you,

Kind regards
Fanzhong

102

Sent.

103

Dear Mr Jonkman,

Can you please send me the “Unofficial FAST Theory Manual” as well?

abdeldjalil.achour@live.fr

Thank you,

Best regards
Achour.A

104

Sent.

105

Dear Jason,

could you please send me the unofficial theory manual?

My email is luca.greco@cnr.it

Thanks a lot.

Kind regards,

Luca

106

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107

Dear Jason,

Could you please send me the unofficial theory manual?

Email : farhadabtahi91@gmail.com

Best regards,

farhad

108

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109

Dear Jason,

I would appreciate if you could also send me the theory manual?

Email: altay@lbb.rwth-aachen.de

Thank you in advance!
Okyay

110

Sent.

111

Dear Dr. Jonkman,

In FAST are centrifugal stiffening effect and gravitational stiffening/softening effect added separated? Or does it come inherently from the formulation?

Thanks,
Saptarshi

112

Dear Saptarshi,

I’m not sure what you mean when you say, “effect added separated”. Regardless, though, the gravitational softening and centrifugal stiffening are inherent in the structural-dynamics formulation.

Best regards,

113

Dear Jason,

Could you please send me the theory manual?

Email : hmzxyk@hotmail.com

Best regards,
Yining.Chen

114

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115

Dear Jason,

Could you please send me the theory manual?

Email : xirenqiang@cczu.edu.cn

Best regards,
Renqiang.Xi

116

Sent.

117

Dear Dr. Jonkman,

I’m trying to match the modal frequencies of my model to that of FAST. For the 1st mode (both tower and blade flapwise) my frequencies are matching. But, for the second mode (again both tower and blade flapwise) my modal frequencies are less compared to that of FAST. For example, from FAST 2nd flapwsie modal frequency is around 1.92Hz while from my model it is 1.56Hz.

I’m using the same procedure of multiplying the derivatives of mode shapes with sectional stiffness and integrating. The same procedure gives me correct frequencies for the 1st modes but not for the second modes.

So, I guess my question is, is there any modal participation factor involved? If so, how should I calculate it? If not, what else can be wrong in my model?

Thank you so much for replying to all my previous question.

Thank you,
Saptarshi

118

Dear Saptarshi,

I don’t think I know enough about what you’ve done to comment. How are you extracting natural frequencies out of your FAST model? How are you extracting natural frequencies out of your model?

Best regards,

119

Dear Dr. Jonkman,

From FAST I’ve used the linearization analysis to calculate the natural frequencies.

From my model, I’m just using the elastic stiffness and the modal mass to calculate the frequency.

Now I understand that the stiffness from FAST linearization will be higher/lower due to centrifugal stiffening and gravity effects. But, I expect that variation to be 1.92(±0.1)Hz. But the difference I’m getting is about 0.4Hz which I think should come from the elastic stiffness.

I’m also getting a difference of almost 1Hz for tower 2nd mode.

I hope you understand what I’m saying.

Thank you again,
Saptarshi

120

Dear Jason,

I would love it if you sent me the theory manual, would this be possible?
Email : jonisak@student.chalmers.se

Thank you in advance!

//Jonatan