Why does OptiStruct result differ greatly from those of ANSYS?

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Answers

  • Q.Nguyen-Dai
    Q.Nguyen-Dai Altair Community Member
    edited May 2018

    If the same FE mesh, same material and the same BC, you have to get 'the same' results.

    So please check:

    • Mesh
    • MAT
    • BC
  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2018
    Altair Forum User said:

    If the same FE mesh, same material and the same BC, you have to get 'the same' results.

    So please check:

    • Mesh
    • MAT
    • BC

    Agree..

     

    Also, unit consistency, Did you scale the model by any chance?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2018
    Altair Forum User said:

    Did you validate the result?

     

    First, we need to investigate from which solver is the error is coming from.

     

    WIth just results values, it is difficult to come to a conclusion. 

    The results of ANSYS are correct. I am solving same model with optistruct to get same results.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2018
    Altair Forum User said:

    If the same FE mesh, same material and the same BC, you have to get 'the same' results.

    So please check:

    • Mesh
    • MAT
    • BC

    Material and BC are all fine. Somewhat mesh is different. Because ANSYS meshes the model automatically whereas in hypermesh I did it manually. But I think it wont make such a big difference.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2018
    Altair Forum User said:

    Agree..

     

    Also, unit consistency, Did you scale the model by any chance?

    Yes, I have cross verified the total mass of the model. Also checked units of Density, E and Poissons ratio. All are fine

     

  • Q.Nguyen-Dai
    Q.Nguyen-Dai Altair Community Member
    edited May 2018

    That's IMPOSSIBLE !!!

    I don't 'believe' to you until you show/share us two your models.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited May 2018

    @Rohit Ch

     

    I am sorry, with limited information, it is very difficult to judge. 

  • gopal_rathore
    gopal_rathore Altair Community Member
    edited May 2018
    Altair Forum User said:

    Sorry I cant share the result file as it is confidential. But i can share values of natural frequencies.

    in Optistuct first natural frequency is 13.87 Hz

    in ANSYS wb first natural frequency is 594 Hz

     

    So can u plz tell me what are the possibilities of wrong input data??

    The difference shown above is huge. Definitely modelling difference is expected in terms of fe steps. To conclude atleast share images of both cases showing constraint , system masses, frequency results etc.

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