How to model a Failure condition with .txt

[frozenheartsaber]

Hello

Sorry to bother again. I hope to know if I can simulate a failure condition with the MATLAB version? I see (MoorDyn-F only) as shown in the documentation. And by the way, if I want to choose the attachment point as the failure position, aside from using generic numbered names like "Point 1" or "Point 2", is there a dedicated term for referring to this point?

Thank you

[RyanDavies19]

Hi @frozenheartsaber,

Unfortunately we haven't brought over the MD-F failures to MD-C yet, mostly because of different approaches to how the object states are stored internally. There is no dedicated term for referring to the failure points, your choice what to call it. The only requirement is that the indexing in the input files is sequential, i.e. the first failure you list has to have the ID failure 1 etc.

[sanguinariojoe]

@RyanDavies19 , if you give me a so far accurate description I can provide you with all the infrastructure to do so.

It is my understanding that you need to create 2 free points on the breaking node position, and 2 lines representing the orig line subparts. Then you want to add the 2 lines and points and remove the orig line from the time integrator (i.e. the states).

[RyanDavies19]

@sanguinariojoe, you pretty much have the general idea of it. Except that in MD-F failures are only possible at existing points, so rather than new lines being created (and deleted) just a single new point is added to the system. All the extra points are allocated during initialization, so in effect they are just 'activated' when a failure occurs. Failures can be tension or time triggered.

This keeps the code quite simple, but does mean you need to know the failure location beforehand. This is pretty doable in most cases, because system weak points are well known. Here is the OpenFAST implementation: OpenFAST/openfast#2214

There's a regression test in OpenFAST that can be used for comparison too.

[sanguinariojoe]

OK, next week I build all the infrastructure to do that!