Simulation time too long

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

Hi,

I'm doing a simulation but the remaining time is too large. I've opened 0001.out file and  I notice there is the same element processing.

What does it mean?

5237  0.1034E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5238  0.1034E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5239  0.1034E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5240  0.1034E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5241  0.1034E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5242  0.1035E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5243  0.1035E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5244  0.1035E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5245  0.1035E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5246  0.1035E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5247  0.1036E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5248  0.1036E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5249  0.1036E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5250  0.1036E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5251  0.1036E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5252  0.1037E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5253  0.1037E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5254  0.1037E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5255  0.1037E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5256  0.1037E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5257  0.1038E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5258  0.1038E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5259  0.1038E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5260  0.1038E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5261  0.1038E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5262  0.1039E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    
  5263  0.1039E-02  0.2000E-06 NODE   197479757   0.0%   0.000      0.7510E+06   0.000      0.7510E+06   1.241    

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2017

    Hi,

    From the engine out file we can trace what is causing for the time step drop.

    It can be an element, a node or an interface.

    •For an element, check the related material (especially its Young modulus and density in case of an elastic-plastic material; and its viscosity in case of a visco-elastic material). There must not be an error in the units system that this data is given in.

    Check the size of the element, since elemental length is proportional to time step.

    •For a node, check the characteristics of connected elements. If the node is on the master side or the slave side of an interface, this interface must be verified.

    •For an interface, the gap of the interface must be verified if some failure happens on the master or the slave side of the interface.

    Once this is cleared you can run the simulation without time step being dropped.

     

    Please watch this webinar which explains about time step control: http://www.altairuniversity.com/learning-library/considerations-about-time-step/

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2017

    Hi, thank you for your reply. I've modified a material that had wrong entry data. Now the simulation runs and gives results but it stops over half time of simulation with mass error.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2017

    Hi,

    Mass error happens when the imposed tie step value is much higher. In the engine out file check for the mass error. Best practice is to have less than 5% added mass (0.05).

     

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  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2017

    I've increased Time step because time simulation remains too long after the check on the materials

     

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited March 2017

    Hi,

    Increasing the time step value will add more mass into the model which will affect the accuracy of the results. As mentioned before the best practice is to have less than 5% added mass (0.05) in the model.

     

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