External mesh via .vtk file

[divyeshkmodi]

Hello,
I am trying to load an external mesh which I created since I wanted a tria-unstructured mesh (the mesh is coarse for testing purposes). It is a square matrix with a circular inclusion in it (as shown below).

I could load the mesh but I do not understand what region I should select.

import felupe as fem

matrix = fem.mesh.read("test.vtk", dim = 2 )[0]
mesh = fem.MeshContainer([matrix])

element = fem.Triangle()
quadrature = fem.TriangleQuadrature(1)
#quadrature.plot(plotter=element.plot(add_point_labels=False, show_points=False),weighted=True,).show()
mesh.plot().show()

region = fem.RegionTriangle(mesh)

It gives me the following error: n

 if len(mesh.cells.T) > 3:
AttributeError: 'function' object has no attribute 'T'

Is it because of the wrong selection of 'Region'?
Also do I need to specify element and quadrature in this case?

Thank you in advance

[adtzlr]

Hi @divyeshkmodi,

you have to create a region on a mesh of a mesh container, not on the mesh container directly. Do you need multiple materials (one for the matrix, one for the circle inside) for your simulation? If so, you must provide two separate vtk-files or split the meshes after importing the vtk-file. Please describe what you want to do and ideally provide the vtk-file(s). I'll try to help you!

import felupe as fem

mesh_container = fem.mesh.read("test.vtk", dim=2)  # read the vtk-file
mesh = mesh_container[0]  # take the first mesh of the mesh-container
region = fem.RegionTriangle(mesh)

A full example with two materials could look like this...

import felupe as fem

r = fem.Rectangle(n=(3, 3))
m = fem.MeshContainer([r.translate(1, 0), r.translate(-1, 0)], merge=True).stack()
m = fem.MeshContainer([m, m.translate(1, 1), m.translate(-1, 1)], merge=True).stack()
m = fem.MeshContainer([m, r.translate(1, 1), r.translate(-1, 1)], merge=True).stack()

container = fem.MeshContainer([r, m], merge=True)
ax = container.imshow(colors=[None, "white"])

mesh = container.stack()
region = fem.RegionQuad(mesh)
field = fem.FieldContainer([fem.FieldPlaneStrain(region, dim=2)])

regions = [
    fem.RegionQuad(container.meshes[0]),
    fem.RegionQuad(container.meshes[1]),
]
fields = [
    fem.FieldContainer([fem.FieldPlaneStrain(regions[0], dim=2)]),
    fem.FieldContainer([fem.FieldPlaneStrain(regions[1], dim=2)]),
]

boundaries, loadcase = fem.dof.uniaxial(field, clamped=True, sym=False)
umats = [
    fem.LinearElasticLargeStrain(E=2.1e5, nu=0.3),
    fem.NeoHooke(mu=1, bulk=2),
]
solids = [
    fem.SolidBody(umat=umats[0], field=fields[0]),
    fem.SolidBody(umat=umats[1], field=fields[1]),
]

move = fem.math.linsteps([0, 1], num=5)
ramp = {boundaries["move"]: move}
step = fem.Step(items=solids, ramp=ramp, boundaries=boundaries)

job = fem.Job(steps=[step])
job.evaluate(x0=field)

plotter = solids[0].plot(show_undeformed=False, style="wireframe")
solids[1].plot(
    "Principal Values of Cauchy Stress",
    component=0,
    label="Matrix - Cauchy Stress (Max. Principal)",
    plotter=plotter,
    show_undeformed=False
).show()

For RegionTriangle, you don't need to specify the element and quadrature scheme. It's a template with default element and quadrature scheme for triangles.

P.S.: Thank you for providing the error message. I enhanced it to be more descriptive in #939.