User element

In this example, we will add support for an element that is currently not supported inside the package: The linear wedge element, C3D6, defined in wedge_element.inp

For this element, it can be defined as a specific Ferrite.Cell type

using Ferrite, FerriteMeshParser
LinearWedge = Ferrite.Cell{3,6,5}

Wedge (alias for Ferrite.Cell{3, 6, 5})

For this element to work with Ferrite, one must define a new reference shape e.g. Wedge and the appropriate interpolations for this shape. In doing so, one also chooses the node order. Following the standard Ferrite conventions, the node order should be the same as in Abaqus as shown above. To change this, it is possible to overload the function FerriteMeshParser.create_cell as follows

create_cell(::Type{LinearWedge}, node_numbers, ::FerriteMeshParser.AbaqusMeshFormat) = LinearWedge(ntuple(j->node_numbers[j], length(node_numbers)))

create_cell (generic function with 1 method)

This setup allows changing the node order for your specific element. It is also possible to use another type which is not a variant of Ferrite.Cell, but rather a subtype of Ferrite.AbstractCell. After these modifications, one can import the mesh by specifying that the Abaqus code C3D6 should be interpreted as a LinearWedge:

grid = get_ferrite_grid("wedge_element.inp"; user_elements=Dict("C3D6"=>LinearWedge));

Giving the following grid

println(typeof(grid))
println(unique(typeof.(getcells(grid))))    # The different cell types in the grid

Ferrite.Grid{3, Ferrite.Wedge, Float64}
DataType[Ferrite.Wedge]

Plain Program

Below follows a version of the program without any comments. The file is also available here: user_element.jl

using Ferrite, FerriteMeshParser
LinearWedge = Ferrite.Cell{3,6,5}

create_cell(::Type{LinearWedge}, node_numbers, ::FerriteMeshParser.AbaqusMeshFormat) = LinearWedge(ntuple(j->node_numbers[j], length(node_numbers)))

grid = get_ferrite_grid("wedge_element.inp"; user_elements=Dict("C3D6"=>LinearWedge));

println(typeof(grid))
println(unique(typeof.(getcells(grid))))    # The different cell types in the grid

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