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TYPE 7 interface with Igap 2 and Inacti 6

Hi,

I am experimenting my simulation run having type :7 interface from constant gap to I Gap 2 option along with Inacti 6.

Case 1: Using constant gap, user defined gap min value, this works fine considering the mesh distances etc. No initial penetration in model on checking through hypercrash

Case 2: Igap : 2, Inacti :6 There are several initial penetrations in model as expected. Warning messages of recommended gap and reduce initial gap. I want to know how take care of these ?

Can this be ignored as I have already provided Inacti : 6

Do I need to make initial penetrations as zero on running in hypercrash with Igap :2 and Inacti 6 settings. Also is hypercrash while checking penetration , is considering Inacti 6?

Kindly let me know,

Thank you.

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Radioss

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Altair Forum User

Hi Gopal,

You can ignore those warnings as you have provided Inacti=6.

Inacti is not considered while checking for penetrations, as this option is to take care of the initial penetrations during the run. It is always advisable to remove the penetrations in the model as it may lead to high energy error and finally run termination.

gopal_rathore

Hi,

Previously I have been using constant gap option , this results in no initial penetrations. But it takes time to assign the gap min values in a big model like car body. However this Igap 2 provides much more faster contact assignment but will come with penetrations as the gap between components is also varying.

Also one thing i have noticed is INACTI 6 starts acting during starter read itself, as the no. of penetrations shown in hypercrash are way highere than that coming after starter read. Is this correct?

Also the solver says, reduce initial gap, does this mean to physically make the gap between master and slave lesser.

For removing the penetrations in this case, do I need to go for earlier techniques of adjusting mesh etc. or any other thing can be used to remove penetration.

RAMGANESH

Dear Gopal,

Due to initial penetrations in model ,it leads to increase in energy error and solving time. Its better to clear the initial penetration in the model before run.

How you defined your interface ? To complete model or to some elements?

Thanks

RAM

RAMGANESH

It may help you.....

Altair Forum User

Hi Gopal,

I think this difference is because of the criteria selected for checking contact interfaces.Please go through the Help Menu for Intersections / Penetrations Criteria in HyperCrash.

This message is especially important in case of a self-impacting interface. For a self impacting interface, if the gap is too high compared to element size, there is a possibility of an initial penetration on the structure on itself. Please check the image below.

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