Optimization Process terminated due to Excessive mesh Distortion?

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

Hello Friends,

 

I am doing shape Optimization in which I got 5 Iteration, in which My Objective function is to minimize static Stress, Constraint- Mass, I have also defined Design Variable with Lower Bound and Upper Bound and Initial value= 0, and move Limit is Default.

 

I don't understand what should be the Problem?

Please Guide me.

 

Thank you

<?xml version="1.0" encoding="UTF-8"?>meshdistortion.PNG

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Answers

  • Punith
    Punith Altair Community Member
    edited February 2017

    Hi,

    it seems that there is a problem with your meshing. When the solver try to move the grid points, some does not move and this creates a distorted mesh.

     

    Regards,

    Punith Guptha

  • Punith
    Punith Altair Community Member
    edited February 2017

    Use the control card GRIDCON (Grid Control). For more info refer to attachment and help files.

    Regards

    PG

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

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Thank you for your reply... I will apply. Before that Just ask you one question.I checked solid element Jacobian from as you can see from Picture, and I found 12 elements which have some Problem may be. When I just unmask with attached elements then it's on the same area where I have apply shapes.

     

    Make sure I have also checked my Grids, which is exactly same. Let's see after applying your solution, what I will get.

     

    Thank you again.

     

    Jay

    <?xml version="1.0" encoding="UTF-8"?>jacobian.PNG

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Again I want to know that GRIDCON Control Card works only for free shape Optimization, and I am not using Free shape Design variable. I don't understand still should I take that control Card or not? As you can see from Picture I am using that Design variable.

    After This Kind of error I got new file with Extension _err.grid

     

     

    Make sure My Optimization process takes more than 18 hours so I want to ensure before applying any new Inputs.

     

    Thank you...

     

    <?xml version="1.0" encoding="UTF-8"?>Designvariable.PNG

  • Punith
    Punith Altair Community Member
    edited February 2017

    can you share .grid file?

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    you mean err.grid file? I can sendyou Print Screen of Difference between my actul Grid and err.Grid. As per the Company Policy I can't share files.

     

    <?xml version="1.0" encoding="UTF-8"?>gridcomparison1.PNG

    <?xml version="1.0" encoding="UTF-8"?>gridcomparison2.PNG

    <?xml version="1.0" encoding="UTF-8"?>gridcomparison3.PNG

    <?xml version="1.0" encoding="UTF-8"?>gridcomparison4.PNG

    <?xml version="1.0" encoding="UTF-8"?>errGridGuide.PNG

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Nayak,

     

    Can you add REMESH option in Opti Controls and try again?

     

    Go to Optimization>> OptiControls>> Activate REMESH

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Thanks Prakash,

     

    After activating REMESH; I got result. but my Simulation takes so much time around 60 hours, can you tell me what exactly Purpose of REMESH here, Is it everytime Change or calculate new matrx or?

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Hi Nayak,

     

    During optimization process, when model runs into element quality error, REMESH activates re-meshing process on the model to improve the element quality internally. After Remeshing is completed optimization run will continue based on the re meshed model.

  • Punith
    Punith Altair Community Member
    edited February 2017

    Hi prakash,

    to resolve this error (lets say I have one or two elements which fails in element quality), can I use a control card > PARAM > CHECKEL > NO?. Does this work as well?

     

    Regards,

    Punith Guptha 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2017

    Punith,

     

    If there is too much cell squish or tet collapse where a tetra element is sqeezed to shell CHECKEL>NO may not work 

  • Punith
    Punith Altair Community Member
    edited February 2017

    Hi Prakash,

    thank you for the Info.

     

    Regards.

    Punith Guptha

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