Different geometry but the same conditions

[Joanne Kwon]

Two boxes were created - one much bigger than the other.
I gave both the same conditions like modulus, permeability, load-curve etc.
However, they gave me two different results - one a viscoelastic curve ('a3' file) and the other a elastic curve ('t55' file).

I thought they should give me the same results since only the box dimensions were changed.

Any comments or suggestions for this behaviour?

Many thanks.

Regards
Joanne

[maas]

Hi Joanne,

I believe the problem might be related to your boundary conditions. You have no free-draining surfaces (zero pressure) set up in your problem. This means that the fluid should not be able to leave the biphasic material. However, the zero-flux boundary condition (which is the default when no zero pressure surfaces are defined) is a so called "natural" boundary condition and therefor not exactly enforced in an FE analysis. The visco-elastic response you observe might be simply a side-effect of this inaccuracy. I would recommend rerunning the problems with at least one free-draining surface defined.

Cheers,

Steve.