ERROR Percentage very high

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

Hi All,

 

Anyone facing this kind of situation before?

my percentage of error went up so high suddenly, but the simulation completed. 

 

image.png.5e77de976876fc7ddad4bc56b6137bc3.png

image.png.3d6e3135782d8c8683fe4e53e3c2d05e.png

 

Thanks.

 

Regards,

Kin Poh

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi Kin Poh,

    The energy error percentage is the parameter that checks the energy conservation during each numerical cycle and it is computed by RADIOSS as a percentage. An increasing Energy Error that reaches ±99% can indicate the simulation has diverged. There are times when a large Energy Error at the end of a simulation can be caused by only one part diverging, but the rest of the model is giving correct results. You can check those nodes, its connected components and review whether any weird behavior is there at the end of the simulation.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi George,

     

    I had troubleshoot it, I think problem is negative volume on it, any idea how to solve this?

    below is the node and the cushion (Solid) property and material

     

    image.png.124a041e8f965bd178c8709da8afcc5e.png

    image.png.0b891742557f7cea30d962acd60dcdc9.png

    image.png.d36d3d513ffb4d14acdbaa0309109143.png

     

    Thanks.

     

    Kin Poh

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi Kin Poh,

    For the solid property can you try running with Isolid=24. 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi george,

     

    Result still the same.

    Any other way?

     

    image.png.7dd335b151e8c0e4ce2b4bea4de298b0.png

     

    image.png.15a9b1580baa0c4f7ed64f0cc038a184.png

     

    Thanks.

     

    Kin Poh

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi Kin Poh,

    This is not an issue. High deformations happening for some elements in the model and those elements are switched to small strain option. Due to high deformations  their characteristic length goes to 0 which results in negative volume. And for large strain formulation the time step of an element also drops badly when the element is compressed. In such cases the solver automatically switches it to small strain. And I think because of that you are getting high energy in the last few cycles, and it seems okay, you can ignore.

    Ismstr = 11 has been developed for Law 70 (foam) and you can try with it. Generally more stable results can be obtained when Ismstr =1, so that from time=0 the elements will be switched to small strain.

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