In Subdyn Inputfile in section MEMBER OUTPUT LIST it is possible to define nodes whose forces etc. will be output. The table has the following structure:
MemberID NOutCnt NodeCnt
(-) (-) (-)
so I wrote
MemberID NOutCnt NodeCnt
(-) (-) (-)
1 1 2
because I only wanted to output M1N2FMxe etc. but the output I expected for node 2 was stored for M1N1FMxe.
Maybe I missunderstood the declaration in subdyn-Input?! Please help me!
Dear Ricardo,
Good timing! We will actually be releasing a major update to SubDyn, as well as FAST v8 with improved hydroelastic coupling making use of SubDyn, early next week. In this release, we are updating the SubDyn documentation a bit to provide more guidance to users. Please wait for this release early next week.
Best regards,
Dear Jason,
thank you for your reply!
Hi @Jason.Jonkman,
Are we considering the gravitational component (effect of gravity) in SubDyn Acceleration member outputs?
If not, is there any way to realize this?
Thank You
Dear @Tom.Jose,
No. The SubDyn acceleration outputs do not include the contribution of gravitational acceleration. If the structure is in equilibrium (no motion), the acceleration outputs will be reported as zero rather than -9.80665 m/s^2 in Z. This is true for other OpenFAST modules as well (including ElastoDyn and BeamDyn).
A feature enhancement request to add this capability to the OpenFAST structural modules (BeamDyn, ElastoDyn, SubDyn) is included in OpenFAST issues: Gravitational acceleration component in local blade sectional accelerations - Feature request · Issue #1603 · OpenFAST/openfast · GitHub. Moreover, the functionality has been added to ElastoDyn for the upcoming v4.0 release due out soon through the following pull request (PR): Add output channels of linear acceleration relative to g in ElastoDyn by luwang00 · Pull Request #1760 · OpenFAST/openfast · GitHub.
You can use this ElastoDyn-focused PR as inspiration/guidance for a SubDyn change if you wish to modify SubDyn directly. If you succeed, it would be great if you could submit a PR to benefit other OpenFAST users.
Best regards,
Dear @Jason.Jonkman,
Does SubDyn acceleration outputs include the contribution of gravitational acceleration in the latest release of OpenFAST v4 ?
Best regards,
Dear @Tom.Jose,
Not yet. I’ve reopened the associated issue on the OpenFAST GitHub site: Gravitational acceleration component in local blade sectional accelerations - Feature request · Issue #1603 · OpenFAST/openfast · GitHub.
Best regards,