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Simulation time too long

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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Altair Forum User

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

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

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).

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

Altair Forum User

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

Altair Forum User

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.