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Files

A mesh of arbitrary geometry is read from file with meshio, in any format it supports, and results are written back the same way:

from torchfem.io import export_mesh, import_mesh

model = import_mesh("plate.vtu", material)
u, f, sigma, epsilon, state = model.solve()
export_mesh(model, "result.vtu", nodal_data={"u": u})

torchfem.io.import_mesh(filename, material, thickness=1.0) 

import_mesh(filename: PathLike, material: MechanicsMaterial | Laminate, thickness: float = 1.0) -> Mechanics

import_mesh(filename: PathLike, material: HeatMaterial, thickness: float = 1.0) -> Heat

Imports a mesh file and returns the matching model type.

The model type follows from the geometry and the element type: a mesh whose nodes all lie in the z=0 plane becomes a Planar model, a non-planar triangle mesh a Shell, and a tetrahedral or hexahedral mesh a Solid. Use import_shell(...) to require a shell.

A HeatMaterial gives the heat model of that geometry, and a Laminate section needs a surface mesh, as only a Shell takes one.

Parameters:

  • filename (PathLike) –

    Path to a mesh file in any format meshio can read.

  • material (Material | Laminate) –

    Material or section assigned to the model.

  • thickness (float, default: 1.0 ) –

    Thickness of a planar or shell model. Unused for a solid.

Returns:

  • FEM ( FEM ) –

    A model of the type described above.

Raises:

  • Exception –

    If the file holds more than one element type, or if its element type has no corresponding model.

The model type follows from the geometry and the element type:

Mesh Model
Any element type, all nodes at z = 0 Planar
Triangles or quadrilaterals that leave the z = 0 plane Shell
Tetrahedra or hexahedra Solid

torchfem.io.import_shell(filename, material, thickness=1.0, offset=0.0) 

import_shell(filename: PathLike, material: MechanicsMaterial | Laminate, thickness: float = 1.0, offset: float = 0.0) -> Shell

import_shell(filename: PathLike, material: HeatMaterial, thickness: float = 1.0, offset: float = 0.0) -> ShellHeat

Import a triangle or quadrilateral mesh as a shell model, flat or not.

A HeatMaterial gives a ShellHeat, anything else a Shell. import_mesh(...) reads a flat surface mesh as Planar instead. offset places the reference surface within the section, as a fraction of thickness from the mid-plane along the element normal, so +0.5 puts it on the top face and the section hangs below the mesh.

Raises:

  • TypeError –

    If the mesh is not a surface mesh.

A flat surface mesh reads as Planar in the table above, so import_shell(...) is how a flat shell is requested explicitly.

torchfem.io.export_mesh(mesh, filename, nodal_data=None, elem_data=None, compress=True)

Writes a model and optional result fields to a mesh file.

The file format is inferred from the suffix of filename by meshio. All tensors are detached and moved to the CPU before writing.

Parameters:

  • mesh (FEM) –

    Model providing the nodes and elements to write.

  • filename (str | PathLike) –

    Output path. Its suffix selects the format.

  • nodal_data (dict[str, Tensor], default: None ) –

    Point data to attach, keyed by name. Shape: (n_nod, ...) per entry.

  • elem_data (dict[str, list[Tensor]], default: None ) –

    Cell data to attach, keyed by name. Each value is a list with one tensor per cell block, so a single-block model takes a one-element list, e.g. {"rho": [rho]}. Shape: (n_elem, ...) per tensor.

  • compress (bool, default: True ) –

    Compress the payload. Applies to .vtu (zlib) and .xdmf/.xmf (gzip) only, and is ignored for other formats.

torchfem.data.get_data(file)

Resolves the path to an example mesh bundled with torch-fem.

The meshes live in torchfem/data and are meant to be passed straight to import_mesh(...), e.g. import_mesh(get_data("plate_hole.vtk"), material).

Parameters:

  • file (str) –

    File name of the bundled mesh, including its suffix.

Returns:

  • Path ( Path ) –

    Absolute path to the file inside the installed package. The path is returned without checking that the file exists.

The bundled meshes are the ones the Examples import.