finer mesh + periodic boundary conditions + excessive distortion

[brunda]

Hello guys,

I have a strange problem at hand.

I have a square plate with periodic boundary conditions.

I have tested the plate in ABAQUS Standard with coarse and fine mesh and it works just as expected.

However, in ABAQUS Explicit, the finer mesh model throws the error "ratio of deformation speed
to wave speed is 0.32563 at increment 4."

The coarser mesh works just fine in ABAQUS explicit.

I am unable to find the bug?

I want to eventually incorporate an element deletion criterion and hence I have to get this fine-mesh plate working in ABAQUS explicit.

Any inputs will be helpful.

Thanks
Brunda

[bburks]

Brunda,

You need to reduce the stable time increment in your fine mesh analysis; the analysis error's out because you are not satisfying the CFL stability criteria. As an alternative, you can add mass scaling to small elements, or materials with high stiffness:damping ratios. However, if you use mass scaling, monitor energy during the analysis, and always benchmark against a solution in which no mass scaling was used.

Best,
Brian

Brian Burks, PhD
Materials Research Engineer
National Institute of Standards and Technology (NIST)