How to avoid negative jacobians while morphing

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hello guys,

 

I want to morph a model but after moving my handles there are always some negative jacobians/folded elements. Also after a small movement (about 1-2mm) there are some folded elements (sometimes only 2 folded elements). The size of my model is around 150mm * 250mm and the element size in the moprhing region is around 0.5mm - 5mm.

Is there any options to avoid folded elements? Maybe meshing with smaller elements or bigger elements or try some various options in the 'morph' subpanel?

 

It would be great if anybody can help me!

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2017

    Hi,

    Please go through the tutorial HM-3690: Remeshing Domains After Morphing, which shows updating the mesh in regions that might have undergone excessive elemental deformation during morphing.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2017

    Ok, thanks!

    I had this thought already to remesh the critical regions. My objective is to do an optimization with the morphed mesh in HyperStudy.

    I don't know if I can reach my objective after remeshing but I will try.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2017

    I tried to remesh like in the tutorial HM-3690 but I got an error that the element angles exceed the tolerance.

    Has anybody an idea what to do now? Should I smooth the mesh before remeshing or are there any other options?

     

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

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2017

    Hi,

    I think this is because of improper movement of handles/nodes. You can try by choosing the fixed nodes and appropriate nodes to move so that the elements are not destroyed.

    Please go through Morphing in the Help Menu where all these options are explained.