Substructure material

Hi everyone,
This is from IEA-15-240-RWT-Monopile_SubDyn.dat ;

------------------ MEMBER X-SECTION PROPERTY data 1/2 [isotropic material for now: use this table for circular-tubular elements] ------------------------
9 NPropSets - Number of structurally unique x-sections (i.e. how many groups of X-sectional properties are utilized throughout all of the members)
PropSetID YoungE ShearG MatDens XsecD XsecT
(-) (N/m2) (N/m2) (kg/m3) (m) (m)
1 2.00000e+11 79.3e9 7800.0 10.0 0.055341
2 2.00000e+11 79.3e9 7800.0 10.0 0.053449
3 2.00000e+11 79.3e9 7800.0 10.0 0.051509
4 2.00000e+11 79.3e9 7800.0 10.0 0.049527
5 2.00000e+11 79.3e9 7800.0 10.0 0.047517
6 2.00000e+11 79.3e9 7800.0 10.0 0.045517
7 2.00000e+11 79.3e9 7800.0 10.0 0.043527
8 2.00000e+11 79.3e9 7800.0 10.0 0.042242
9 2.00000e+11 79.3e9 7800.0 10.0 0.041058

Looks like these properties belong to steel material. I just want to know which part of the wind turbine these 9 “PropSetID” represent. I want to change the substructure to concrete while my tower should remain steel. Should I change all these 9 Young Modulus to concrete’s Young Modulus or should I change just some of them?

Best regards,

Kaan Akkaş

Dear @Kaan.Akkas,

In the OpenFAST model of the IEA Wind 15-MW RWT atop the monopile, the monopile is modeled within SubDyn and the tower is modeled within ElastoDyn, with the transition piece / interface joint between ElastoDyn and SubDyn at 15 m above MSL. The cross-sectional properties you are referring are used within the monopile model in SubDyn.

Best regards,

Dear @Jason.Jonkman,
Thank you for your answer, it enlightened me. However, I am confused about “MEMBER X-SECTION PROPERTY data 1/2 [isotropic material for now: use this table for circular-tubular elements]”. Is this table referring to the cross-section of the transaction piece, which is circular-tubular, 15 m above MSL? Or, is this referring to monopile itself?

This is another tables from Subdyn (19 njoints and 18 nmembers) ;

---- STRUCTURE JOINTS: joints connect structure members (~Hydrodyn Input File)—
19 NJoints - Number of joints (-)
JointID JointXss JointYss JointZss JointType JointDirX JointDirY JointDirZ JointStiff
(-) (m) (m) (m) (-) (-) (-) (-) (Nm/rad)
1 0.00000 0.00000 -30.0000 1 0.0 0.0 0.0 0.0
2 0.00000 0.00000 -29.999 1 0.0 0.0 0.0 0.0
3 0.00000 0.00000 -25.0000 1 0.0 0.0 0.0 0.0
4 0.00000 0.00000 -24.999 1 0.0 0.0 0.0 0.0
5 0.00000 0.00000 -20.0000 1 0.0 0.0 0.0 0.0
6 0.00000 0.00000 -19.999 1 0.0 0.0 0.0 0.0
7 0.00000 0.00000 -15.0000 1 0.0 0.0 0.0 0.0
8 0.00000 0.00000 -14.999 1 0.0 0.0 0.0 0.0
9 0.00000 0.00000 -10.0000 1 0.0 0.0 0.0 0.0
10 0.00000 0.00000 -9.999 1 0.0 0.0 0.0 0.0
11 0.00000 0.00000 -5.0000 1 0.0 0.0 0.0 0.0
12 0.00000 0.00000 -4.999 1 0.0 0.0 0.0 0.0
13 0.00000 0.00000 0.0000 1 0.0 0.0 0.0 0.0
14 0.00000 0.00000 0.001 1 0.0 0.0 0.0 0.0
15 0.00000 0.00000 5.0000 1 0.0 0.0 0.0 0.0
16 0.00000 0.00000 5.001 1 0.0 0.0 0.0 0.0
17 0.00000 0.00000 10.0000 1 0.0 0.0 0.0 0.0
18 0.00000 0.00000 10.001 1 0.0 0.0 0.0 0.0
19 0.00000 0.00000 15.0000 1 0.0 0.0 0.0 0.0
------------------- BASE REACTION JOINTS: 1/0 for Locked/Free DOF @ each Reaction Node ---------------------
1 NReact - Number of Joints with reaction forces; be sure to remove all rigid motion DOFs of the structure (else det([K])=[0])
RJointID RctTDXss RctTDYss RctTDZss RctRDXss RctRDYss RctRDZss SSIfile [Global Coordinate System]
(-) (flag) (flag) (flag) (flag) (flag) (flag) (string)
1 1 1 1 1 1 1
------- INTERFACE JOINTS: 1/0 for Locked (to the TP)/Free DOF @each Interface Joint (only Locked-to-TP implemented thus far (=rigid TP)) ---------
1 NInterf - Number of interface joints locked to the Transition Piece (TP): be sure to remove all rigid motion dofs
IJointID ItfTDXss ItfTDYss ItfTDZss ItfRDXss ItfRDYss ItfRDZss [Global Coordinate System]
(-) (flag) (flag) (flag) (flag) (flag) (flag)
19 1 1 1 1 1 1
----------------------------------- MEMBERS --------------------------------------
18 NMembers - Number of frame members
MemberID MJointID1 MJointID2 MPropSetID1 MPropSetID2 MType COSMID
(-) (-) (-) (-) (-) (-) (-)
1 1 2 1 1 1
2 2 3 1 1 1
3 3 4 1 2 1
4 4 5 2 2 1
5 5 6 2 3 1
6 6 7 3 3 1
7 7 8 3 4 1
8 8 9 4 4 1
9 9 10 4 5 1
10 10 11 5 5 1
11 11 12 5 6 1
12 12 13 6 6 1
13 13 14 6 7 1
14 14 15 7 7 1
15 15 16 7 8 1
16 16 17 8 8 1
17 17 18 8 9 1
18 18 19 9 9 1
------------------ MEMBER X-SECTION PROPERTY data 1/2 [isotropic material for now: use this table for circular-tubular elements] ------------------------
9 NPropSets - Number of structurally unique x-sections (i.e. how many groups of X-sectional properties are utilized throughout all of the members)
PropSetID YoungE ShearG MatDens XsecD XsecT
(-) (N/m2) (N/m2) (kg/m3) (m) (m)
1 2.00000e+11 79.3e9 7800.0 10.0 0.055341
2 2.00000e+11 79.3e9 7800.0 10.0 0.053449
3 2.00000e+11 79.3e9 7800.0 10.0 0.051509
4 2.00000e+11 79.3e9 7800.0 10.0 0.049527
5 2.00000e+11 79.3e9 7800.0 10.0 0.047517
6 2.00000e+11 79.3e9 7800.0 10.0 0.045517
7 2.00000e+11 79.3e9 7800.0 10.0 0.043527
8 2.00000e+11 79.3e9 7800.0 10.0 0.042242
9 2.00000e+11 79.3e9 7800.0 10.0 0.041058

I can see the z-coordinate here (for 19 njoints). Are these tables related to the first table (with 9 propsetid)?

Best regards,

Kaan

Dear @Kaan.Akkas,

The format of the SubDyn input file is well documented on readthedocs: 4.2.5.3. Input Files — OpenFAST v3.5.3 documentation.

Basically though, you define joints, which get interconnected by members. You define the cross-sectional properties at each end joint of the member.

Best regards,