[Bug?] Meshing changes input Geometry

Merula_20758
Merula_20758 Altair Community Member
edited November 2020 in Community Q&A

Hey guys,

 

maybe I am unaware of a setting which causes this, but at least to me, this is strange. I have a modified version of the CClip Tutorial and when I mesh it, the geometry changes and neither the geometry nor the mesh has a node where it should be.

.gif and .hm attached.

 

Thanks in advance,

Merula

<?xml version="1.0" encoding="UTF-8"?>MeshChangesGeom.gif

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Answers

  • tinh
    tinh Altair Community Member
    edited June 2017

    Hi,

    Try enter panel option (press O)

    >graphic

    Change geom refinement level to higher number

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited June 2017

    Element nodes are not coming in the expected location because of unavailability of fixed point. Just add fixed point & you would get elements node at desired location.

    <?xml version="1.0" encoding="UTF-8"?>Fixed point.JPG

    <?xml version="1.0" encoding="UTF-8"?>Mesh with wireframe.JPG

  • Merula_20758
    Merula_20758 Altair Community Member
    edited June 2017

    Thanks for your replies.

    The problem I saw in this was not that the mesh is not at the desired location but that meshing changes the geometry which it should never do from my understanding.

    If it is just a visualization issue as tinh suggested, turning up the refinment layer should result in the same visualization as before the mesh, which it doesn't.

     

    So my question is: Has the geometry changed (before / after the mesh), and if yes, why and if thats a bug or completely normal behaviour.

     

    Thanks for your help!

  • Rahul Rajan_21763
    Rahul Rajan_21763 New Altair Community Member
    edited June 2017

    This is not a bug, but normal behaviour because of geometry.While meshing Hypermesh does not change geometry after mesh.BTW where you modelled this CAD?

  • tinh
    tinh Altair Community Member
    edited June 2017

    Yes, it could be due to cad defect, sometimes fix points are not stick to surf

    so they will not anchor node, and final mesh boundary => is real cad boundary

    sometimes I change geom refinement to higher level and can see that.

    but in your case, cannot.

    Try export surface to STP/IGS then import it again

    My hm14 cannot open your file but, I create such surface by hypermesh and can mesh it without problem

  • Q.Nguyen-Dai
    Q.Nguyen-Dai Altair Community Member
    edited June 2017

    @Merula: Your geometry does not have 'fixed point' at this place.

    Do do as suggestion of @Rahul R.

    I confirm No bug of software about this issue.

     

  • Merula_20758
    Merula_20758 Altair Community Member
    edited November 2020

     

    Altair Forum User said:

    This is not a bug, but normal behaviour because of geometry.While meshing Hypermesh does not change geometry after mesh.BTW where you modelled this CAD?

     

    The geometry has been modeled in 3d via Opencascade, the middlesurface has been extracted, so the surface comes from hypermesh geometry operation.

    If the meshing does not change the geometry, why can you see the visualization change when I press 'Return' after the mesh.

     

    @tinh The mesh as the real boundary of the geometry would be ok for this case as the point gets nearly touched by the mesh line. I can see why HM would adapt the mesh there.

     

    .Step File attached.

    Thanks again for your kind replies

     

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