XFEM elements

XFEM elements

XFEM elements allow simulations where the unknown fields are enriched through the partition of unity concept. Two elements are currently available for 2D XFEM simulations: TrPlaneStress2dXFEM (subclass of TrPlaneStress2d) and PlaneStress2dXfem (subclass of PlaneStress2d).

TrPlaneStress2dXFEM element

Table 47 TrPlaneStress2dXFEM element summary

Keyword	TrPlaneStress2dXFEM
Description	Two dimensional 3-node triangular XFEM element
Specific parameters	[czmaterial (in)] [nipcz (in)][useplanestrain (in)]
Parameters	czmaterial: Interface material for the cohesive zone. (If no material is specified, traction free crack surfaces are assumed.) nipcz: Number of integration points used on each segment of the cohesive zone. useplanestrain: If plane strain or plane stress should be assumed. 0 implies plane stress and 1 implies plane strain.
Unknowns	Two continuous (standard) DOFs (u-displacement, v-displacement) and a variable number of enriched DOFs (can be continuous or discontinuous).
Approximation
Integration	Elements cut by an XFEM interface are divided into subtriangles.
Features
CS properties
Loads
Nlgeo
Status
Tests/Examples	sm/xFemCrackVal.in

PlaneStress2dXfem element

Table 48 PlaneStress2dXfem element summary

Keyword	PlaneStress2dXfem
Description	Two dimensional 4-node quad XFEM element
Specific parameters	[czmaterial (in)] [nipcz (in)][useplanestrain (in)]
Parameters	czmaterial: Interface material for the cohesive zone. (If no material is specified, traction free crack surfaces are assumed.) nipcz: Number of integration points used on each segment of the cohesive zone. useplanestrain: If plane strain or plane stress should be assumed. 0 implies plane stress and 1 implies plane strain.
Unknowns	Two continuous (standard) DOFs (u-displacement, v-displacement) and a variable number of enriched DOFs (can be continuous or discontinuous).
Approximation
Integration	Elements cut by an XFEM interface are divided into subtriangles.
Features
CS properties
Loads
Nlgeo
Status
Tests/Examples	sm/plasticRemap1.in, sm/xfemCohesiveZone1.in, sm/xfemMultipleCracks1.in, sm/xFemCrackValBranchCZ.in, sm/xFemIntersectingCracks.in, sm/xfemCrackPropMatForce.in, sm/xFemCrackValBranch.in