Tendon failure in FAST modeling

Provide feedback, request enhancements, and get help with wind-turbine computer-aided engineering tools.

Moderators: Bonnie.Jonkman, Jason.Jonkman

Jason.Jonkman
Posts: 4394
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Wed Aug 07, 2019 6:55 am

Dear Yajun,

When you zeroed out the fairlead load by customizing the source code, you didn't actually modify how the mooring line was modeled in MAP++, correct? Thus, while FAST does not feel the tension of the mooring line that has failed, the tension in the line as calculated by MAP++ is not actually zero, correct?

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Bertrand.Canetti
Posts: 23
Joined: Thu Oct 31, 2019 6:35 pm
Organization: University College of Cork
Location: Ireland

Re: Tendon failure in FAST modeling

Postby Bertrand.Canetti » Wed Nov 27, 2019 10:37 am

Dear Jason,

I have never recompiled, but I saw some help about it on the forum.

But I wonder, is it simply possible to directly edit FASTv8\Source\dependencies\MAP\MAP.f90 with a text editor (Notepad++)?

Also, the tension of the line (between the platform and the fairlead) is actually the tension of the fairlead, is that right?

In the MAP++ input file, what is fix, connect, and vessel exactly for the nodes?

Thank you for your help,

Best regards,
Bertrand

Jason.Jonkman
Posts: 4394
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Wed Nov 27, 2019 2:02 pm

Dear Bertrand,

Yes, you can edit the source files with any text editor. Of course, you will need a compiler to compiler.

Yes, the line tension at the fairlead is the tension of the fairlead.

In MAP++, "fix", "vessel", and "connect represent the boundary conditions at the end of a line:
  • "fix" can be considered an anchor (fixed to the inertial frame);
  • "vessel" can be considered a fairlead (where the line connects to the platform/vessel);
  • "connect represents a line-to-line interconnection.
I hope that helps.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov

Bertrand.Canetti
Posts: 23
Joined: Thu Oct 31, 2019 6:35 pm
Organization: University College of Cork
Location: Ireland

Re: Tendon failure in FAST modeling

Postby Bertrand.Canetti » Thu Nov 28, 2019 1:24 am

Dear Jason,

Thank you for your answer.

So to do load case 3.7, I did edit the MAP.F90 source file lie the following:

Code: Select all

DO i = 1,2
   IF (t<100) THEN
   y%ptFairleadLoad%Force(1,i) = -y%FX(i)
   y%ptFairleadLoad%Force(2,i) = -y%FY(i)
   y%ptFairleadLoad%Force(3,i) = -y%FZ(i)
   ELSE
   y%ptFairleadLoad%Force(1,i) = 0
   y%ptFairleadLoad%Force(2,i) = 0
   y%ptFairleadLoad%Force(3,i) = 0
   END IF
   END DO
   DO i = 3,y%ptFairleadLoad%NNodes
   y%ptFairleadLoad%Force(1,i) = -y%FX(i)
   y%ptFairleadLoad%Force(2,i) = -y%FY(i)
   y%ptFairleadLoad%Force(3,i) = -y%FZ(i)
   END DO
       


with this MAP input file:

---------------------- LINE DICTIONARY ---------------------------------------
LineType Diam MassDenInAir EA CB CIntDamp Ca Cdn Cdt
(-) (m) (kg/m) (N) (-) (Pa-s) (-) (-) (-)
Material 0.0766 113.35 7.536E8 1.0 0 0 0 0
---------------------- NODE PROPERTIES ---------------------------------------
Node Type X Y Z M B FX FY FZ
(-) (-) (m) (m) (m) (kg) (mˆ3) (N) (N) (N)
1 fix 837.6 0 depth 0 0 # # #
2 Vessel 40 0 -14.0 0 0 # # #
---------------------- LINE PROPERTIES ---------------------------------------
Line LineType UnstrLen NodeAnch NodeFair Flags
(-) (-) (m) (-) (-) (-)
1 Material 835.35 1 2 tension_fair tension_anch
---------------------- SOLVER OPTIONS-----------------------------------------
Option
(-)
repeat 240 120

and I obtain this Surge (x-axis) Sway (y-axis) chart, which seems totally wrong:

Image

with the fairlead tension of line 1 never equal to zero (T1 y-axis, time x-axis):

Image


It is like the source code modification was not taken into account.

Do you have an idea why? Probably because I did not "compile" it. I am not familiar at all with this.

Thank you for your help,

Bertrand

Jason.Jonkman
Posts: 4394
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Fri Nov 29, 2019 8:57 am

Dear Bertrand,

When you change the source code, you'll need to recompile for the changes to take effect.

Best regards,
Jason Jonkman, Ph.D.
Senior Engineer | National Wind Technology Center (NWTC)

National Renewable Energy Laboratory (NREL)
15013 Denver West Parkway | Golden, CO 80401
+1 (303) 384 – 7026 | Fax: +1 (303) 384 – 6901
nwtc.nrel.gov


Return to “Computer-Aided Engineering Software Tools”

Who is online

Users browsing this forum: No registered users and 1 guest