time step less or equal dtmin for solid element

Altair Forum User

Hi, we try to model an old scooter crash but we have some problem with the interface. For modelling the selfcontact interface of the front part we use interface type 7 (gapmin=0,9; fric=0,2; inacti=1).

We added in the master all the component  and the same for the slave. We try to run 50ms of analisys but at 23ms we have this error 'time step less or equal dtmin for solid element' after a lot of message 'rupture of sell element' and 'delete of shell element' and the analisys stop. 

we set eng_dt with dtmin=2e-7 and tscale=0,9. 

we think the problem was in interface but we can find it.

 

thanks

Altair Forum User

Hi @Baro

 

Gapmin activates impact when the relative distance between the contact parts is equal to the value. Can you run the model without any friction and set Inacti as 5 and check if that helps.

 

If not, can you share the .out file, please?

Altair Forum User

Hi, thanks for your answer. I try to use that options but it doesn't run. I try type 20 interface and it seems that it works. But now there's another problem because the % error jump  from 0.2 to 99 after 43000 cycle and it stop..

in the .out file i see this warning after 43000 cycle :  '*WARNING MINIMUM TIME STEP   0.9583E-09 IN INTERFACE          3' repeated many times

 

Altair Forum User

Hi @Baro

 

For interface time step is calculation is related to stiffness and thickness of master and slave. 

 

Please check the material parameters, unit consistency and also use Istiff= 3 which makes the interface stiffer and check if this helps.

 

If you still face the problem, please share the model file. 

Altair Forum User

Hi, i've the same error.

here the model file. thanks!

 

Altair Forum User

@Baro

 

Thank you for sharing the file. I will check and update you soon. 

Altair Forum User

Altair Forum User said:

@Baro

 

Thank you for sharing the file. I will check and update you soon. 

 

Thank you so much!

Altair Forum User

Hi Baro,

 

I have a suggestion, please try this and let us your findings:

 

Can you create self-contact for each component instead of creating a single self-contact for all components?

 

Altair Forum User

Hi, i tried to do a single self_contact for each component of the front of vehicle. But at 15ms it started to give me 'rupture of shell element' and at the end of the simulation it deleted all element of the model..

here the out file of the last analisys

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