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Question about the Timoshenko beam of OC4 semi
Dear David,
I noticed you have uploaded the OC4 semi model to the website. I wonder will you also update the shear stiffness information in the tower data table in your simulation/turbine file?
thanks
Chris
Dear David
I found the information, you may ignore my question.
thanks
Chris
Dear David,
I wonder if the Timonshenko function is activated, all the elements including the blade, tower, substructure elements will follow same approach of Timonshenko? all elements will follow the same beam modeling approach?
thanks
Kobe
Dear David,
I have a question about your example of semi-sub “Load sensor locations for flexible OC4 ME calculation”, I would like to know is it only flexible model allow the local joint/member force can be extracted? If a rigid model, only the mass matrix of substructure is specified, so I guess the internal forces cannot be determined without the member stiffness information? Can QBlade read the mass matrix and the table of SUBELEMENTS at the same time? Or QBlade can only read either the table?
thank you
Chris
Hi Chris,
you can assign the beam element type to each structural member individually by specifying the variable BEAMTYPE in each member’s structural data table.
You are correct that internal forces cannot be obtained from a rigid body. When a force sensor is placed on a rigid body, it will only report the applied external forces, such as hydrodynamic forces.
When modeling a substructure, rigid members, flexible members, and lumped masses can be combined arbitrarily. The lumped inertia matrix (SUBMASS) and other lumped matrices are always positioned at their reference location and are rigidly constrained to the transition piece of the substructure. Using the constraint table (SUBCONSTRAINTS), you can then also attach flexible and/or rigid members to the substructure.
BR,
David
Dear David,
Thanks for your reply. I noticed in your OC5 5MW MSWT model Version 5.0.0 10.5281/zenodo.10634206 Feb 8, 2024, you have assigned both the table of SUBELEMENTS and SUB_MASS of floater mass matrix with SUBELEMENTSRIGID. I wonder is this approach can give some approximate or reasonable members forces in the floater? This approach seems can give the member forces with LPMD method. Have you tried to compare with other software?
thanks a lot.
Chris
Hi Chris,
in the Hexafloat model only the counterweight at the very bottom of the floater is modeled as rigid with a lumped mass matrix. The”upper” parts of the floater, near the sea surface, are modeled as flexible.
As mentioned before, it’s up to the user to combine the possible elements and modeling choices in a way that makes sense.
We have conducted a lot of verification work within the Floatech project http://floatech-project.com/, checkout the project deliverables.
BR,
David
