Is there a reliable way to define a structural load over a FSI?

tubertottubertot Member
edited December 2020 in Structures

I'm using Ansys 2019 R3 Academic. In a Static Acoustics module, I am trying to define a pressure over the structural region (i.e. at the FSI) to simulate the effect of atmospheric pressure. I find that sometimes Mechanical allows me to define this pressure without issue, and sometimes it gives me an error stating "This structural load should be defined on bodies belonging to Physics Region which has structural definition set to Yes."

What I think is happening is sometimes Mechanical interprets the shared surface as belonging to the structural region and allows me to define a pressure over it, but sometimes it interprets it as acoustic region and produces this error. Is there a workaround or best practice that can help avoid this problem?

In the below images I have hidden the overlying acoustic region since they obscure the surface of interest.


  • Static acoustics is not for applying a pressure load to a structure - it is used for other applications.

    From the help manual and if we search for static acoustics, the main use is for prestress (but we do not apply the pressure on the acoustic domain, which are dummy elements they do not do anything, but on the structure directly):

    From manual: "You use the Static Acoustics analysis as a pre-stress environment for future downstream Modal Acoustics or Harmonic Acoustics analyses."

    Thank you


  • Thank you Erik, for your response. I am using the Static Acoustics analysis as a pre-stress environment for a Harmonic Acoustics analysis. Part of my intended pre-stress is applying the atmospheric pressure over my structure, since I expect this to cause a membrane deflection (it is a membrane suspended over a vacuum cavity). I am applying the pressure directly to the structure but (presumably) because the surface is shared between structural and acoustic domains it sometimes does not allow me to define it.

    Hope that clarifies.

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