Beam elements in FEBio?

[svizec]

It would be very beneficial for some applications to have an option to use beam elements. The beam profile could just be circular, as that would probably account for most applications (surfaces can already be used for rectangular profiles). Is this somewhere on the roadmap by any chance?

[SteveMaas1978]

A rudimentary beam formulation has been implemented in FEBio. It is based on the formulation by Simo and Vu-Quoc,
https://doi.org/10.1016/0045-7825(88)90073-4

Here is an example file that should work with the current develop version.
cantilever.zip

Please keep in mind that it is very likely that the implementation and the interface will change over next few weeks and months and we continue this development.
Let us know if you have any questions or find any issues.

[SteveMaas1978]

Make sure to install the development version. (The latest release version does not have this new feature yet.)

See here for instructions on how to get the latest development update.

[svizec]

Make sure to install the development version. (The latest release version does not have this new feature yet.)

See here for instructions on how to get the latest development update.

I realized that as soon as I replied to the original comment. It works as expected with the CLI solver and it completes the simulation, but the .feb file cannot be imported into FEBio Studio (Dev Version 2.4.0.a0387dfe2).

The results can be visualized in FEBio Studio. Sphere-capped tubes when selecting "Render beams as solids" look a bit strange IMHO when the beam elements do not form a loop (both free ends could be flat faces). I assume this is due to how beams are rendered as solids in VTK. This is just a minor detail I noticed when looking at the results.

Great work implementing the beam elements inside FEBio. I am looking forward to seeing how it develops further.

[SteveMaas1978]

Looks like I forgot to add support for reading quadratic beam elements in FEBio Studio. I have that fixed, and the file should load correctly in FBS. (For Windows, you can do a dev update now, for linux and mac tomorrow.)

The beam visualization in FBS is indeed rather crude at the moment. I hope to add options to define beam profiles and then render the beam using the proper profile. For now, I've changed the rendering so that the beam ends are flat.

Let me know if you find any other issues.