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Hollow sections don't simulate?

Richard_InvRichard_Inv Member Posts: 35 PRO
edited August 26 in Simulation

So I have a simple rectangular frame, attached to two fixed pins.

It simulates fine when the frame is solid, takes about 1 minute
But when I make the frame hollow (about 2mm thick), it just will not simulate. Just spins the loading wheel

Setup pictured below, if anyone has any ideas?

image.png
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Comments

  • S1monS1mon Member Posts: 3,488 PRO

    From other threads, the issue is likely that Onshape simulation doesn't (yet) have a shell element.

    https://forum.onshape.com/discussion/comment/119867/#Comment_119867

    Simon Gatrall | Staff Mechanical Engineer | Carbon, Inc.

  • glen_dewsburyglen_dewsbury Member Posts: 1,134 PRO
    edited August 26

    This seams to work OK. Maybe the extra fixed locations are giving trouble.

    https://cad.onshape.com/documents/7cd9097db9a39677f054b262/w/956877d55e01351d69173503/e/990d30f4c89a064240efd9b5

    image.png
  • S1monS1mon Member Posts: 3,488 PRO

    @glen_dewsbury How thin is the tubing wall? From what I understand it's an aspect ratio issue which can trigger the simulation status to never resolve.

    Simon Gatrall | Staff Mechanical Engineer | Carbon, Inc.

  • glen_dewsburyglen_dewsbury Member Posts: 1,134 PRO

    S1mon. How far does the aspect ratio need to change before this won't work?

    The original frame was 0.375 x 0.375 x 0.0625.

    Increased to 1.25 x 2.5 x 0.125 and still works.

    image.png
  • S1monS1mon Member Posts: 3,488 PRO

    @glen_dewsbury I really don't know. I tried to simulate a load on a sheet metal shelf part and was told by @GregBrown it wouldn't work because there wasn't a shell element in simulation.

    Simon Gatrall | Staff Mechanical Engineer | Carbon, Inc.

  • glen_dewsburyglen_dewsbury Member Posts: 1,134 PRO

    !! No sheet metal??

  • eric_pestyeric_pesty Member Posts: 2,307 PRO

    It sort of works but it makes 3D meshes of thin parts so it's very inefficient. The thinner the part relative to the overall size the worst it gets…

    I've had reasonable success with parts up to 30x20 made out of 0.1" thick material but even that runs very slowly…

  • glen_dewsburyglen_dewsbury Member Posts: 1,134 PRO

    Tried this with a sheet metal. It worked notably faster as 0.5 thick compared to 0.06 thick.

    https://cad.onshape.com/documents/7cd9097db9a39677f054b262/w/956877d55e01351d69173503/e/aec6f04eb8be80881c9fed77

    image.png
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