Abaqus Explicit: issue with mass in import analysis

[andrea96]

Hello everyone,
I am having an issue with doing an import analysis between Explicit simulations.
The simulation stops after the first increment because the ratio of deformation speed to wave speed exceeds 1.0000 in at least one element in one of the imported instances.
It also shows that the % change mass is over 8.

I was thinking that this is due to a mass scaling problem definition? In the second simulation I set up the mass scaling with the same values of the previous one but it doesn't seem to be working.
If I use a smaller mass scaling (from 5E-07 to 1E-08) the simulation doesn't converge (after 24 hours).

Anyone has an idea of this issue or how to solve it?

Thank you!!

 

[FEA way]

This error (especially when occurring so early) is usually caused by wrong units or unrealistic input values so double-check all your settings. It shouldn't be caused by mass scaling itself unless it's ridiculously high. In your case, it's pretty low actually.

 

[andrea96]

Thank you for your reply.

When I run the first simulation with the same MS setting (5E-07), the simulation runs to convergence with ok results.
Then I set up the import simulation and use the same MS. Since material properties and geometries are the same, shouldn't it work the same?

Thanks.

 

[FEA way]

Can you share the files ? It's hard to say what's going on there. Maybe it's a matter of conditions applied to the imported part.