Defining fibers

hi all,

i was wondering if there are any specific documantion/information i can find in order to analyze fibers in fenics?
any specific functions or something
till now i modeled a hyperelastic non linear, non homogenius rod and now my professor want to apply my code on fibers, he told me that he thinks that there are specific function for fibers

tried to search something online but didnt found anything specific. would be happy to hear is there is something like that or not


As far as I know, there is no built-in function in FEniCS to define fibers in a hyperelastic material model. You need to define it in your code based on your specific strain energy function.

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It is relatively straightforward to define anisotropic hyperelastic constitutive models accounting for fibers, you just need to decide on a specific model

can you advise on how to create a cylinder like model?
i tried to use cylinder = Circle(Point(0.2, 0.2), 0.05), but it has no length
and this one is not working for me even with mshr library
cylinder = Cylinder(Point(0, 0, -1), Point(0, 0, 1), 0.5, 0.5)
geometry = cylinder
maybe its not updated

i found this command, but the plot seems to be not smooth, is it something i should expect? does it depend on the resolution maybe?

this is what i used

radius = 0.01
height = 1.0
resolution = 64  # Number of divisions along the radius

cylinder = mshr.Cylinder(fe.Point(0, 0, 0), fe.Point(0, 0, height), radius, radius)
mesh = mshr.generate_mesh(cylinder, resolution)

this is what i get


once i changed the radius i got smoother , but still not very smooth, any way to fix that?

mshr has not been supported for a long time (many years). As far as I remember it used CGAL as the back end. Consider instead and the corresponding DOLFINx demos dolfinx/python/demo/ at main · FEniCS/dolfinx · GitHub. Particularly the case using high order geometry: dolfinx/python/demo/ at e64178c679d4186ed1c5ab3c2e48b4ff28feef6c · FEniCS/dolfinx · GitHub. Other high quality mesh generators are also available.

Speaking of fibers in a hyperelastic material model, you should have a continuum model defining the constitutive equations. For example, in collagen fibers in biological tissue, you need to define the orientation and concentration of the fibers. There might be other parameters in the model (e.g., the rate of uncrimping collagen fibers etc.).
You may want to have a look at this paper where one of these models has been implemented in FEniCS.

yes im actually working on collogen fibers, i will take a look on that, thanks

is there any reference on how to model those fibers in fenics? cause for some reason my university is not appearing there and i cant access the paper

Have a look at this small implementation

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