Additional Multiphasic Contacts

[mfarnham]

Hello,

I was wondering if it would be possible to implement a tied contact for use with multiphasic materials. If I'm not mistaken, the only contact that can be used with triphasic or multiphasic materials is the multiphasic-sliding contact, is this true?

On another note, when using a biphasic material with a mixed-solid, is this considered a multiphasic material? I'm getting an error at the contact line, so I assume the biphasic contact I am using is the problem here.

Thanks!

[ateshian]

Hi Margot,

I was wondering if it would be possible to implement a tied contact for use with multiphasic materials.

Yes, we can implement a tied multiphasic contact interface (similar to the tied biphasic contact interface). I'll let you know when this is ready.

If I'm not mistaken, the only contact that can be used with triphasic or multiphasic materials is the multiphasic-sliding contact, is this true?

In principle, all the contact interfaces currently available in FEBio can be used with triphasic and multiphasic materials. However, they will not enforce all the continuity requirements for these materials: Elastic contact interfaces will enforce continuity of normal displacement and normal traction; the biphasic contact will also enforce continuity of the effective fluid pressure and normal fluid flux; the multiphasic contact will also enforce continuity of the effective solute concentrations and normal solute fluxes. A biphasic contact interface automatically sets free-draining conditions (zero fluid pressure) on the portion of contact surfaces which are not in contact at each time step. A multiphasic contact interface does the same with solutes (sets ambient effective fluid pressure and effective solute concentrations outside the contact region).

when using a biphasic material with a mixed-solid, is this considered a multiphasic material?

No, if the material is declared in the input file as "biphasic", using a solid mixture for its solid constituent does not make it a multiphasic material for the purpose of a FEBio analysis.

Best,

Gerard

[mfarnham]

Dr. Ateshian,

Thank you so much for your response!

Best,
Margot

[ateshian]

Hi Margot,

I have implemented a tied-multiphasic contact interface. It will become available in the upcoming FEBio 2.6 release. It is similar to the "tied-biphasic" interface, it just requires the additional specification of a <concentration_penalty> tag.

Best,

Gerard

[mfarnham]

This is great, thank you so much!

Best,
Margot