Explicit dynamics end time/time step definition

[monipmf]

Hi everyone,

I'm new to explicit dynamics simulation and I'm having some trouble to establish the end time based on the mesh and material. I'm currently using Ansys.
Some information about the model:
[ul]
[li]two bodies: one fixed and the other with initial velocity =7 m/s[/li]
[li]shell bodies with quad mesh (element size 4 mm)[/li]
[li]materials: both made of structural steel (very simple model)[/li]
[li]flexible bodies[/li]
[/ul]


Anyone have had a similar problem of bodies penetrating each other during the collision? Any tips?

Thanks in advance

 

[FEA way]

Make sure that contact between the bodies is properly defined. Also check their masses.

 

[monipmf]

Hi FEA way,

thanks for your reply.
I checked the masses but having a short experience it's difficult to evaluate it. I understand that higher masses can give more stability to the model right?
In this case the obstacle weights 1.5kg and the shocking object 0.5 kg

Contact is frictionless between parts and body interaction automatic set up.
I also noticed that when I have very small end time it penetrates completely so probably wavelength has not time enough to capture the presence of the obstacle's mesh (please correct me if I'm wrong).
When I calculate it based on sound speed and element quad shell size the deltat is very small though.

Would you have any other suggestion for correcting this model (or any fellow in the forum)? In the meantime I'll keep going with theoretical material.

Thanks again!

The result shown below has also a problem of too large energy error

 

[FEA way]

Masses are important for contact stiffness evaluation. Wrong mass/inertia definitions may cause penetrations.