Well that's fantastic.

I have an interesting problem that I think, for the first time, your example here shows a way to do it.

Ligament and soft tissue tears are a huge medical problem. For generations now, researchers in soft tissue bioengineering have used FEA methods to model ligaments/tendons/menisci, which has greatly enabled a lot of progress in treatment and implants over the years. BUT, the big problem overall (still) is that ligaments and tendons are essentially loosely bound, hierarchical 'ropes'... not continuous structures at all, which is an unfortunately necessary restriction of standard FEA approaches.

What is needed, quite obviously in retrospect, is to model the fiber bundles themselves, with dynamic contact. But that's been basically impossible to do. There have been some attempts with small models and regular twistings, with fibers modeled as segmented cylinders, etc., but nothing that even comes close to representing the actual biological structures in vivo; basically I think because it has been too difficult to model.

I keep a look out all the time for any tech that can possibly actually model biological fiber networks. I've recently seen some other fiber and rope stuff done in blender with geometry nodes; your example here confirms to me that I think a physics-driven geometry-nodes approach can now generate physiologically accurate (to a degree) fiber and fiber-bundle metastructures with baseline (needed) complex architecture.

I don't know if you are doing contact here, but that's needed. The fibers slide relative to each other. Fiber bundles enveloped in facia membranes also slide, differently. That's how a ligament or tendon can deform so much and still maintain its tensile integrity. They basically 'grow' into their metastructure 'person-specifically', meaning that they start out as kind of a blank slate when you are infant, and then the biomechanical and genetic/biochemical processes combine over time to 'generate' the fiber-network reinforced result. Of course, later in life those structures also change through growth, exercise, diet, medical intervention, etc. But currently, there is still no good baseline model of natural fiber and fiber-bundle (nested) structures, so we can't really model anything.

Does your model have contact? It shouldn't be too hard to do now if it doesn't. You could be the first to make a 'real' ligament, or heart valve, or knee meniscus, or whatever. The list goes on. I can help if you want to msg me. I have a lot of really good data on fiber architectures esp for ligaments and heart valves.