XFEM manager and associated records

The XFEM manager record specifies the number of enrichment items and the simulation options common to all of them. It is created when nxfemman is 1; see Components size record.

The functions used for enrichment — Heaviside, absolute value, branch functions and so on — are not specified here, nor is the geometrical representation of an enrichment item, such as a polygon line or a circle: both are specified for each enrichment item separately.

Note

OOFEM currently supports XFEM simulations of cracks and material interfaces in 2D.

XFEM manager record

Record syntax

XfemManager numberofenrichmentitems (in) [numberofnucleationcriteria (in)] [numberofgppertri (in)] [numberoftrirefs (in)] [enrdofscalefac (rn)] [debugvtk (in)] [vtkexport (in)] [exportfields (ia)]

Parameters

numberofenrichmentitems (in)

Number of enrichment items, whose records follow.

[numberofnucleationcriteria (in)]

Number of nucleation criteria, whose records follow the enrichment items.

[numberofgppertri (in)]

Number of Gauss points in each subtriangle of a cut element. Default 12.

[numberoftrirefs (in)]

How many times a subtriangle is refined. Default 0.

[enrdofscalefac (rn)]

Scale factor applied to the enrichment DOFs, which can improve the conditioning of the system matrix. Default 1.0.

[debugvtk (in)]

1 writes additional debug VTK files; 0 is the default.

[vtkexport (in)]

A nonzero value turns on the XFEM VTK export. When it is on, exportfields becomes mandatory.

[exportfields (ia)]

Which XFEM fields to export. Mandatory when vtkexport is nonzero, and used by the vtkxmlxfem export module; see Export modules.

Enrichment item records

The specification of an enrichment item consists of several consecutive lines. See the test tests/regression/sm/xFemCrackValBranch.in for a complete example.

First line — the enrichment item

EntType num (in) [enrichmentfront (in)] [propagationlaw (in)]

[enrichmentfront (in)]

Number of an enrichment front. The front of the enrichment is treated separately: we may, for example, use branch functions at a crack tip and Heaviside enrichment along the rest of the crack. Optional.

[propagationlaw (in)]

Number of a rule for crack propagation. Optional.

Warning

Crack propagation is still highly experimental.

Second line — the enrichment function

EntType num (in)

Third line — the geometric description

EntType num (in) plus the attributes the chosen geometry needs. The number and type of those attributes vary with the geometry: a centre and a radius for a circle, a number of points for a polygon line, and so on.

Fourth line — the enrichment front

EntType num (in) plus its attributes. Present only if an enrichmentfront was specified on the first line.

Fifth line — the propagation law

EntType num (in) plus its attributes. Present only if a propagationlaw was specified on the first line.