Continuous Fiber Distribution for modeling cartilage

[Shamimur Akanda]

Hello,

I have a question regarding implementing fiber properties. According to FEBio user manual, I can use ellipsoidal fiber distribution using a solid mixture container. Again, there is another option for ellipsoidal fiber distribution under continuous fiber distribution. Here, it confuses me. If I want to model a cartilage with ellipsoidal fibers having properties and orientation varying throughout the thickness, how should I approach? Thank you in advance.

Regards,
Shamimur

[ateshian]

Hi Shamimur,

The two constitutive models are different and you can look up their exact form in the User's Manual. Which one you should use depends on which experimental cartilage data you want to be able to fit. There is no single constitutive model that works perfectly well with all cartilage experimental data. The ellipsoidal fiber distribution model was first introduced in this paper and fitted to experimental data in this paper. The continuous fiber distribution model was fitted to experimental data in this paper, but only assuming a spherical fiber distribution.

If you want properties that vary through the thickness, you would need to fit either of these models to depth-dependent experimental data. The last paper cited above does that for human patellofemoral joint cartilage, assuming a spherical distribution. If you want specific ellipsoidal parameters, you would need to fit data for cartilage tested along orthogonal directions. Experimental data do exist for these testing configurations, but as far as I know they have not been fitted to either of these ellipsoidal fiber distribution models.

Best,

Gerard

[Shamimur Akanda]

Hello Dr. Ateshian,

Thank you very much for your explanation.

Shamimur