Random time-varying concentrated loads?
Random time-varying concentrated loads?
(OP)
Hi,
Is there a way to impose random time-varying concentrated loads on a structure? Something similar to DLOAD user-subroutine maybe?
I want to load a structure with time-varying pressure forces and viscous forces.
Thanks.
Is there a way to impose random time-varying concentrated loads on a structure? Something similar to DLOAD user-subroutine maybe?
I want to load a structure with time-varying pressure forces and viscous forces.
Thanks.





RE: Random time-varying concentrated loads?
you can generate a random sequence of numbers between 0.0 and 1.0 (outside ABAQUS, previous to the analysis), according to whatever probabilistic distribution you want,
then put the random sequence in an *AMPLITUDE definition, and attach the *AMPLITUDE definition to a *CLOAD definition.
...and by the way I was thinking that pressure should be distributed, therefore DLOAD subroutine should be ok for such random force generating coding.
RE: Random time-varying concentrated loads?
So...? Any other hints?
RE: Random time-varying concentrated loads?
Thanks,
J
RE: Random time-varying concentrated loads?
RE: Random time-varying concentrated loads?
can you please share your UTRACLOAD subroutine? How do you pass the pressure magnitudes on? I guess you are doing some flutter analysis, but for static aeroelasticity, a DLOAD wouldnt be more appropriate?
Cheers
RE: Random time-varying concentrated loads?
I don't think you can find something interesting in my UTRACLOAD routine since it is case study dependent. But t oanswer your question, I am writing from FLUENT the resultant vector of the forementioned loads on each face element at the interface fluid/structure and I am loading them in ABAQUS with UTRACLOAD where you need to supply T_USER (vector direction) and ALPHA (vector's magnitude) for each element loaded with DLOAD (TRVECxNU).
Best regards,
RE: Random time-varying concentrated loads?
actually I was asking for the bits of your subroutine just to have a model for my problem. I've never used subroutines, so it's a bit confusing at the beginning. From what I understood, the DLOAD subroutine, as well as UTRACLOAD, is called for each integration point. That means I have to read in my subroutine the CP distribution previously interpolated at each of the integration point location and pass actually the magnitude of the CP at a particular integr point. Is that right? I'm doing the static aeroelastic study only. Have you done this before?
Cheers
RE: Random time-varying concentrated loads?