Welcome to the FEBio Forum. This forum serves the community of FEBio and FEBio Studio users and developers. Forum participants are encouraged to post questions, as well as answer posts from others. A broad level of participation is encouraged, to create a vibrant community that helps improve the quality and usefulness of these open-source/free software products. Moderators are here to assist with explaining novel features, addressing bug reports and reviewing feature requests, but the effectiveness of the forum depends critically on the participation of experienced users who can assist novices or share ideas and models that explore challenging problems. Please feel free to join in this effort. You can subscribe to forums by pressing the "Subscribe" button at the top of the forum. This will allow you to stay up to date on recent activity on the forum.
The FEBio software downloads and knowledgebase can be found here.
SeekingSuggestions regarding modeling cartilage with depth dependent fiber properties
SeekingSuggestions regarding modeling cartilage with depth dependent fiber properties
Hello,
I want to model a cartilage using the three layer (Superficial, middle, deep zone). What is the best approach to provide depth dependent fiber properties in a cartilage model? Thank you in advance.
The easiest approach is to partition the mesh into three layers and then assign a different material to each of the three parts. If you want more variability through the depth, you can assign equations to some of the material parameters (preliminary support for this is available in the beta release of FEBio Studio), or you can assign a mesh data section to the different parts (not supported yet in FEBioStudio, but available in FEBio3). If you let me know which approach you want to take, I'm happy to elaborate.
Cheers,
Steve
Department of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of Utah
Here is where the map is assigned to the material parameter. Also, note line 3377, which defines an output field for this parameter so you should be able to look at the map in PostView or FEBioStudio.
Code:
<var type="parameter['fem.material[0].E']=E"/>
Unfortunately, we don't have much support for this yet in FEBioStudio (although we will soon!) so for now you'll have to make the changes manually in the feb file. Let us know if you have any questions about this.
I'm also trying to model cartilage with different fiber orientations at different depths/layers. I divided my model into 3 layers and aim to specify a differently oriented fiber in each layer, (As per literature fibers oriented parallel to the surface in the Superficial layer, Random distribution in Middle layer, and fibers vertical to the surface in the Deep layer). Would you be able to advise me on what is the best fiber type to use in febio for this? I've been playing around with different fibers and was able to run the models using the 'fiber-exp-pow', '"spherical fiber distribution" and "spherical fiber distribution sbm" type. The 'fiber-exp-pow' seemed to me the easiest way to do it, but I could not figure out if there is a way to specify the density of these fibers within the tissue?
Would you be able to point me to some literature examples of using different type of fibers and what are their advantages?
Any help would be greatly appreciated,
Regards,
Kinga
Thank you very much for the example. However, I was trying to partition my mesh into three different layers using "select elements" tool in Mesh option. But when I tried to choose one specific layer, this tool was selecting elements from other layers too. So, I could not partition the mesh correctly. Do you know if there is any other direct way to partition the mesh? Thank you.
There is an option in FEBioStudio that allows you to either ignore or respect partition boundaries in selections. It is on (i.e. respect) by default, but perhaps for some reason it got turned off. Go to Tools\Options... and then in the Options dialog box, select Selection in the left pane, and then set the Respect Partitions option to Yes. Let me know if that worked.
Cheers,
Steve
Department of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of Utah
Thanks a lot for your reply. I can divide the mesh properly in three different layers in simpler geometry. But when I am using a curved geometry, somehow, I can't divide the geometry properly. If it is possible can I send you my mesh file? Thank you.
Can you tell me a bit how the paper "Hip chondrolabral mechanics during activities of daily living: Role of the labrum and interstitial fluid pressurization" established continuous fibril variation throughout the thickness using DataMap Plugin? Thank you in advance.
The datamap plugin allows you to interpolate material parameters between two surfaces. In FEBio2, this actually also required a special implementation of the material, however in FEBio3 the datamap plugin is integrated into the code and can be used with most materials. That said, I did find a bug in the code related to this in FEBio3, but if you reach out to me via email I can send you the fixed version. I've also attached an example that shows the use of the datamap feature.
I have been trying to implement Datamap plugin in my model for varying material properties. The file is not at all opening in febio. I guess there might be some kind of syntax/text error related to the plugin. It would be really appreciated if you can look into it. I am attaching the file here for your consideration.
Which version of FEBio are you using? I am trying to get this to work in FEBio3, but I'm running into issue. The first issue is unrelated to the datamap plugin, but you are missing a "scheme" property in the "continuous fiber distribution". The other issue is related to the fact the parameters you are trying to map have not been updated in FEBio3 and this would definitely not have worked in FEBio2. I'll try to find some time to get this problem to work in FEBio3 and I'll let you know if I get it working.
Cheers,
Steve
Department of Bioengineering, University of Utah
Scientific Computing and Imaging institute, University of Utah
I have tried both FEBio 2.9 and FEBio3. I could not get this file to work. Regarding the other issue, are you referring to the semi principal axis (spa) that have not been updated in FEBio3? If that so, is there any other platform, I can map these parameters? Thank you for your time.
Comment