Is there any subroutine to mannually assign distributed loads in Subdyn

Dear developers,

I want to manually assign distributed loads on fixed substructures modelled in Subdyn. That is to say, is it possible to assign different load at different position of fixed substructure in Subdyn or via point-point mapping?

Are there some subroutines to achieve this goal?
Or I can try to modify the source codes. Could you please give me some hints?

Regards,
Ran

Dear @Ran.Tu,

Presumably you are referring to applying loads to a SubDyn module within a coupled OpenFAST simulation; is that correct?

You can apply point loading to the SubDyn module through Structural Control (StC) submodel of ServoDyn by setting NumSStC > 0 in ServoDyn and StC_DOF_MODE = 4 in the StC input file. For each point load that you want to apply, you must create a separate StC input file (SStCfiles). See the StC documentation for more information: 4.2.11. Structural Control (SrvD) — OpenFAST v3.2.0 documentation.

Best regards,

Thank you Jason,
That is what I want.

In addition, at present can OpenFAST realize distributed spring (for both force and moment) representing monopile embedded in soil? Is there any subroutine for users to program their own distributed spring on substructure? I know FASTv7 has subroutine called UserTwrLd.f90. Is there analogous subroutine in OpenFAST v3.2?

Regards,
Ran

Dear @Ran.Tu,

No, a distributed springs (DS) soil-structure interaction model has not yet been implemented in OpenFAST and there is no equivalent to UserTwrLd.f90 from FAST v7 in OpenFAST.

That said, linear coupled springs (CS) foundation model has been implemented in SubDyn (via SSIfile) and the pending release of the SoilDyn module has a “placeholder” for future implementation of P-Y curves (see the following PR for more information: SoilDyn -- soil dynamics module by andrew-platt · Pull Request #986 · OpenFAST/openfast · GitHub).

Best regards,