Tendon failure in FAST modeling

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

Moderators: Bonnie.Jonkman, Jason.Jonkman

Yajun.Ren
Posts: 17
Joined: Mon Jan 21, 2019 6:54 am
Organization: The University of Edinburgh
Location: UK

Re: Tendon failure in FAST modeling

Postby Yajun.Ren » Mon Mar 25, 2019 5:29 am

Dear Jason,

Thank you for your helpful information. Now one mooring line out of the three is simulated to be broken, but how would I know which specific line is broken? According to the output fair lead tension, I think the cable in line with the inflow wave direction was operated. Am I right?

Best regards,
Yajun

Jason.Jonkman
Posts: 4221
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Mon Mar 25, 2019 8:26 am

Dear Yajun.

Correct. The lines are numbered how they are entered in the MAP++ input file. In the OC3-Hywind model, line 1 is directed from the fairlead to the anchor in the zero-degree wave-propagation direction.

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

Yajun.Ren
Posts: 17
Joined: Mon Jan 21, 2019 6:54 am
Organization: The University of Edinburgh
Location: UK

Re: Tendon failure in FAST modeling

Postby Yajun.Ren » Tue Mar 26, 2019 8:19 am

Dear Jason,

Thank you for your reply. One more question is that could I simulate another line to be broken by compiling the source code?

Best regards,
Yajun

Jason.Jonkman
Posts: 4221
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Wed Mar 27, 2019 8:12 am

Dear Yajun,

The source-code change I described above could be applied to any of the lines ("i") in the MAP++ input file.

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

Yajun.Ren
Posts: 17
Joined: Mon Jan 21, 2019 6:54 am
Organization: The University of Edinburgh
Location: UK

Re: Tendon failure in FAST modeling

Postby Yajun.Ren » Fri Mar 29, 2019 8:20 am

Dear Janson,

I changed the coordination of the nodes in the MAP++ input file as follow (to simulate the other line to be broken):

Node Type X Y Z M B FX FY FZ
(-) (-) (m) (m) (m) (kg) (mˆ3) (N) (N) (N)
1 fix -426.935 739.47 depth 0 0 # # #
2 Vessel -2.6 4.5 -70.0 0 0 # # #

However according to the output line tension, although the number of broken line changed from line1 to line3, the actual broken line is still the one align with load direction. I guess I might modify the input file incorrectly, could you please give any advice?

Best regards,
Yajun

Jason.Jonkman
Posts: 4221
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Mon Apr 01, 2019 7:13 am

Dear Yajun,

I'm not sure, but perhaps the numbering of the lines in MAP++ is effected by the location of the specified line and the use of the "repeat" option for the other two lines. Do you get the response you expect if you prescribe all six nodes and all three lines directly within the MAP++ input file?

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

Yajun.Ren
Posts: 17
Joined: Mon Jan 21, 2019 6:54 am
Organization: The University of Edinburgh
Location: UK

Re: Tendon failure in FAST modeling

Postby Yajun.Ren » Mon Apr 01, 2019 8:40 am

Hi Jason,

I tried to specific the MAP input file with full properties of the 3 lines:

---------------------- LINE DICTIONARY ---------------------------------------
LineType Diam MassDenInAir EA CB
[-] [m] [kg/m] [N] [-]
Material 0.09 77.7066 384.243E6 0.001 1.0E8 0.6 -1.0 0.05
---------------------- NODE PROPERTIES ---------------------------------------
Node Type X Y Z M B FX FY FZ
[-] [-] [m] [m] [m] [kg] [mˆ3] [N] [N] [N]
1 fix 853.87 0 depth 0 0 # # #
2 Vessel 5.2 0 -70.0 0 0 # # #
3 fix -426.9350 739.4731 depth 0 0 # # #
4 Vessel -2.6000 4.5033 -70.0000 0 0 # # #
5 fix -426.9350 -739.4731 depth 0 0 # # #
6 Vessel -2.6000 -4.5033 -70.0000 0 0 # # #
---------------------- LINE PROPERTIES ---------------------------------------
Line LineType UnstrLen NodeAnch NodeFair Flags
[-] [-] [m] [-] [-] [-]
1 Material 902.2 1 2 tension_fair tension_anch
2 Material 902.2 3 4 tension_fair tension_anch
3 Material 902.2 5 6 tension_fair tension_anch
---------------------- SOLVER OPTIONS-----------------------------------------
Option
[-]
repeat 240 120

And I got the error:

Timestep: 8 of 3000 seconds. Estimated final completion at 17:13:46.

FAST_Solution:CalcOutputs_And_SolveForInputs:SolveOption2:InflowWind_CalcOutput:CalcOutput:IfW_Uni
formWind_CalcOutput:GetWindSpeed:Height must not be negative.
IfW_UniformWind_CalcOutput: Error calculating the wind speed at position (4.3404, -1.98360E-02,
-1.39375E-02) in the wind-file coordinates

FAST encountered an error at simulation time 8.2875 of 3000 seconds.
Simulation error level: FATAL ERROR

Aborting FAST.



I also tried to change the "repeat" option from 240 120 to 120 0 with the previous change of node coordination, but it didn't work. Would you suggest me to do any other modification of the input file? Thank you very much.

Best regards,
Yajun

Jason.Jonkman
Posts: 4221
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Mon Apr 01, 2019 9:03 am

Dear Yajun,

When specifying all six nodes and three lines, you should eliminate the repeat option altogether.

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

Yajun.Ren
Posts: 17
Joined: Mon Jan 21, 2019 6:54 am
Organization: The University of Edinburgh
Location: UK

Re: Tendon failure in FAST modeling

Postby Yajun.Ren » Tue Apr 02, 2019 7:16 am

Dear Jason,

I'm sorry to bother again. I tried your solution, specifying the full line properties and delete the angle of "option" by the following input content:

---------------------- LINE DICTIONARY ---------------------------------------
LineType Diam MassDenInAir EA CB CIntDamp Ca Cdn Cdt
(-) (m) (kg/m) (N) (-) (Pa-s) (-) (-) (-)
Material 0.09 77.7066 384.243E6 0.001 1.0E8 0.6 -1.0 0.05
---------------------- NODE PROPERTIES ---------------------------------------
Node Type X Y Z M B FX FY FZ
[-] [-] [m] [m] [m] [kg] [mˆ3] [N] [N] [N]
1 fix -426.9350 739.4731 depth 0 0 # # #
2 Vessel -2.6000 4.5033 -70.0000 0 0 # # #
3 fix -426.9350 -739.4731 depth 0 0 # # #
4 Vessel -2.6000 -4.5033 -70.0000 0 0 # # #
5 fix 853.87 0 depth 0 0 # # #
6 Vessel 5.2 0 -70.0 0 0 # # #
---------------------- LINE PROPERTIES ---------------------------------------
Line LineType UnstrLen NodeAnch NodeFair Flags
[-] [-] [m] [-] [-] [-]
1 Material 902.2 1 2 tension_fair tension_anch
2 Material 902.2 3 4 tension_fair tension_anch
3 Material 902.2 5 6 tension_fair tension_anch
---------------------- SOLVER OPTIONS-----------------------------------------
Option
[-]


However, the result shows that it is still the line in 0 degree to be broken.

I also tried to compile the source code as:

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


But it didn't work.

Best regards,
Yajun

Jason.Jonkman
Posts: 4221
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Tue Apr 02, 2019 1:28 pm

Dear Yajun,

When you say you that it "didn't work", you mean that with your source code changes, you see the tension of line 3 (connecting nodes 5 and 6) going to zero, and the others not? I don't really see how this is possible given your code change, where you are setting the tensions of lines 1 and 2 to zero. I suggest running the model in debug mode to see what the problem may be.

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

Yajun.Ren
Posts: 17
Joined: Mon Jan 21, 2019 6:54 am
Organization: The University of Edinburgh
Location: UK

Re: Tendon failure in FAST modeling

Postby Yajun.Ren » Thu Aug 01, 2019 2:55 am

Dear Jason,

I disabled one of the mooring lines using the previous code modification, the output tension value seems reasonable. However, when I tried to plot the trace of the platform by correlating surge and sway, the figure shows that when line#1(directed alone the positive x axis) is disconnected, the turbine drifts away alone the positive x direction(as I attached below). As my speculation, the platform should move towards the opposite direction to the broken line, could you please help to explain?

Best regards
Yajun
Attachments
trace.JPG
trace.JPG (48.91 KiB) Viewed 281 times

Jason.Jonkman
Posts: 4221
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Thu Aug 01, 2019 7:08 am

Dear Yajun,

Can you share the MAP++ input file you are using? The input file you posted in your Apr 02, 2019 post above has line 1 upwind (negative X) and to the left (positive Y) when looking downwind.

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

Yajun.Ren
Posts: 17
Joined: Mon Jan 21, 2019 6:54 am
Organization: The University of Edinburgh
Location: UK

Re: Tendon failure in FAST modeling

Postby Yajun.Ren » Thu Aug 01, 2019 7:48 am

Dear Jason,

Thank you for your reply. The MAP++ file I used is:

---------------------- LINE DICTIONARY ---------------------------------------
LineType Diam MassDenInAir EA CB CIntDamp Ca Cdn Cdt
(-) (m) (kg/m) (N) (-) (Pa-s) (-) (-) (-)
Material 0.09 77.7066 384.243E6 0.001 1.0E8 0.6 -1.0 0.05
---------------------- NODE PROPERTIES ---------------------------------------
Node Type X Y Z M B FX FY FZ
(-) (-) (m) (m) (m) (kg) (mˆ3) (N) (N) (N)
1 fix 853.87 0 depth 0 0 # # #
2 Vessel 5.2 0 -70.0 0 0 # # #
---------------------- LINE PROPERTIES ---------------------------------------
Line LineType UnstrLen NodeAnch NodeFair Flags
(-) (-) (m) (-) (-) (-)
1 Material 902.2 1 2 tension_fair tension_anch
---------------------- SOLVER OPTIONS-----------------------------------------
Option
(-)
repeat 240 120

I think by using the above mooring properties, the broken line should be the one directed to the positive x-axis.

Best regards,
Yajun

Jason.Jonkman
Posts: 4221
Joined: Thu Nov 03, 2005 4:38 pm
Location: Boulder, CO
Contact:

Re: Tendon failure in FAST modeling

Postby Jason.Jonkman » Thu Aug 01, 2019 9:44 am

Dear Yajun,

Yes, I agree that it line one is directed downwind, so, I would have guess that eliminating that line would shift the platform upwind. It has hard to tell what is going on without examining other output channels. I would suggest scanning through other outputs to ascertain what is happening or using the visualization functionality of OpenFAST to animate the response.

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

Yajun.Ren
Posts: 17
Joined: Mon Jan 21, 2019 6:54 am
Organization: The University of Edinburgh
Location: UK

Re: Tendon failure in FAST modeling

Postby Yajun.Ren » Wed Aug 07, 2019 2:39 am

Dear Jason,

Sorry for the late reply. I just fixed the previous problem, which was a coding mistake. However a new question is that, the tension of the line with zero y%ptFairleadLoad%Force(:,i) increases at the broken time rather than drop to 0, is that reasonable?

Best regards,
Yajun


Return to “Computer-Aided Engineering Software Tools”

Who is online

Users browsing this forum: No registered users and 1 guest