CrackMeshCut3DUserObject

Creates a UserObject for a mesh cutter in 3D problems

Overview

This class: (1) reads in a mesh describing the crack surface, (2) uses the mesh to do initial cutting of 3D elements, and (3) grows the mesh incrementally based on prescribed growth functions. The code is interfaced with domain integral methods to allow nonplanar crack growth based on empirical propagation direction and speed laws.

For crack-growth problems, "size_control" sets the target spacing used when advancing and refining the cutter front, while"min_elem_area" prevents the growth algorithm from adding very small or nearly degenerate triangles to the cutter mesh. The number of growth advances performed in one update is controlled by "n_step_growth".

Surface-Cutting Segment, Active and Inactive Nodes

When a crack reaches a free surface of the body, only part of the cutter-mesh boundary lies inside the FEM volume. The cutter boundary is therefore partitioned into one or more active boundary segments, each consisting of a contiguous list of nodes bracketed by inactive endpoints:


inactive_start — active_1 — active_2 — ... — active_N — inactive_end

Classification is done on every growth step by testing whether each cutter-boundary node lies inside the FEM body:

A boundary node is active** if it lies inside the body.
A boundary node is inactive** if it lies outside the body.

The crack front used by DomainIntegralAction and the propagation laws is composed only of active nodes. The inactive endpoints act as anchors for the active segment and define where the crack front meets the free surface.

Motion of the Inactive Node

Each active node advances in the direction and by the increment determined by the growth law (function-prescribed or hoop-stress-based). The inactive endpoints are not driven by their own growth law; instead they inherit growth direction and increment from the active neighbor they are connected to. So the candidate position for an inactive endpoint is


candidate = previous_inactive_position + active_direction * active_growth_length

Keeping the inactive node above the free surface

After computing the candidate, the algorithm checks whether it still lies outside the body:

Candidate outside the body. The inactive node has moved into free space and no correction is required; the candidate is used as the new position.
Candidate inside the body. Growth would push the inactive node into the FEM volume (typical when the free surface curves toward the cutter or when the cutter enters a concave corner). The candidate is snapped to the closest point on the body's exterior surface and then nudged outward by 0.1 * size_control so the result lies reliably above the free surface for the next step's classification.

For every face on the body's exterior, the algorithm computes the point on that face closest to the candidate. This is the perpendicular projection of the candidate onto the face's plane when that projection lies within the face's polygon; otherwise it is the nearest point on one of the polygon's edges. The face whose closest point is nearest to the candidate is selected, and that point becomes the snap location. The same rule covers two important cases without special handling:

Curved free surfaces. Because the curved surface is tiled by many small flat polygons, the candidate naturally snaps to the polygon of the tiling that is closest to it; the snap point varies smoothly across the curvature.
Concave corners. When the candidate is just past a corner edge shared between two adjacent faces, the edge-fallback gives the same point on that shared edge for both faces. The outward nudge then pushes the inactive node into the empty space outside the corner rather than burying it back inside either face.

Minimum-displacement reuse

After the projection step, the inactive endpoint's actual displacement from its previous position to the new position is compared against half of the active neighbor's growth length. If


||new_position - previous_inactive_position|| < 0.5 * active_growth_length

the inactive node is left at its current location and the existing node is reused for the new crack-front element. This avoids producing degenerate sliver triangles when projection clips the inactive motion almost back to where it started (for example, when an inactive endpoint is pressed against a wall and growth would only push it deeper). When this rule fires, the connection between the old front and the new front shares a node at that endpoint, and the zero-area sliver triangle that would otherwise be generated is dropped by the existing minimum-area filter.

note

The closest-point projection only considers surfaces tagged into a sideset. A free surface that exists geometrically but is not assigned to any sideset will be invisible to this projection, and an inactive endpoint pushed into the body through such an untagged surface will not be corrected. When meshing for crack-growth simulations, every exterior face that the cutter can interact with should be assigned to a sideset.

note

This active/inactive logic governs only the cutter-mesh growth algorithm — that is, how the cutter advances and where its free-surface endpoints are placed each step. The XFEM cutting itself is unaffected: every FEM element intersected by the cutter mesh is cut normally regardless of whether the intersection happens near an active interior, an inactive endpoint, or a reused node.

Example Input Syntax

This example shows the Mesh block in Listing 1 needed for creating the cutter mesh along with the CrackMeshCut3DUserObject block in Listing 2. The mesh block in Listing 1 defines two separate meshes. The cutter mesh is created in the read_in_cutter_mesh block and must have "save_with_name" set in order to specify this mesh in CrackMeshCut3DUserObject shown in Listing 2 using "mesh_generator_name". The mesh used by the FEM simulation is specifed in the FEM_mesh block in this example and "final_generator"=FEM_mesh must be set because only the FEM_mesh will be used for the finite-element solution and the mesh created by read_in_cutter_mesh will be ignored by the solution.

Listing 1: Setting up the mesh block contain simulation and cutter meshes.

[Mesh<<<{"href": "../../syntax/Mesh/index.html"}>>>]
  [read_in_cutter_mesh]
    type = FileMeshGenerator<<<{"description": "Read a mesh from a file.", "href": "../meshgenerators/FileMeshGenerator.html"}>>>
    file<<<{"description": "The filename to read."}>>> = mesh_edge_crack.xda
    save_with_name<<<{"description": "Keep the mesh from this mesh generator in memory with the name specified"}>>> = mesh_cutter
  []
  [FEM_mesh]
    type = GeneratedMeshGenerator<<<{"description": "Create a line, square, or cube mesh with uniformly spaced or biased elements.", "href": "../meshgenerators/GeneratedMeshGenerator.html"}>>>
    dim<<<{"description": "The dimension of the mesh to be generated"}>>> = 3
    nx<<<{"description": "Number of elements in the X direction"}>>> = 5
    ny<<<{"description": "Number of elements in the Y direction"}>>> = 5
    nz<<<{"description": "Number of elements in the Z direction"}>>> = 2
    xmin<<<{"description": "Lower X Coordinate of the generated mesh"}>>> = 0.0
    xmax<<<{"description": "Upper X Coordinate of the generated mesh"}>>> = 1.0
    ymin<<<{"description": "Lower Y Coordinate of the generated mesh"}>>> = 0.0
    ymax<<<{"description": "Upper Y Coordinate of the generated mesh"}>>> = 1.0
    zmin<<<{"description": "Lower Z Coordinate of the generated mesh"}>>> = 0.0
    zmax<<<{"description": "Upper Z Coordinate of the generated mesh"}>>> = 0.2
    elem_type<<<{"description": "The type of element from libMesh to generate (default: linear element for requested dimension)"}>>> = HEX8
  []
  final_generator = FEM_mesh
[]

Listing 2: CrackMeshCut3DUserObject that uses the cutter mesh created in Listing 2.

[UserObjects<<<{"href": "../../syntax/UserObjects/index.html"}>>>]
  [cut_mesh]
    type = CrackMeshCut3DUserObject<<<{"description": "Creates a UserObject for a mesh cutter in 3D problems", "href": "CrackMeshCut3DUserObject.html"}>>>
    mesh_generator_name<<<{"description": "Mesh generator for the XFEM geometric cutter."}>>> = mesh_cutter
    growth_dir_method<<<{"description": "choose from FUNCTION, MAX_HOOP_STRESS"}>>> = MAX_HOOP_STRESS
    size_control<<<{"description": "Criterion for refining elements while growing the crack"}>>> = 1
    n_step_growth<<<{"description": "Number of steps for crack growth"}>>> = 1
    growth_rate<<<{"description": "Function defining crack growth rate"}>>> = growth_func_v
  []
[]

Input Parameters

blockThe list of blocks (ids or names) that this object will be applied
C++ Type:std::vector<SubdomainName>
Controllable:No
Description:The list of blocks (ids or names) that this object will be applied
growth_dir_methodFUNCTIONchoose from FUNCTION, MAX_HOOP_STRESS
Default:FUNCTION
C++ Type:MooseEnum
Options:MAX_HOOP_STRESS, FUNCTION
Controllable:No
Description:choose from FUNCTION, MAX_HOOP_STRESS
growth_direction_xFunction defining x-component of crack growth direction
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function defining x-component of crack growth direction
growth_direction_yFunction defining y-component of crack growth direction
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function defining y-component of crack growth direction
growth_direction_zFunction defining z-component of crack growth direction
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function defining z-component of crack growth direction
growth_increment_methodFUNCTIONchoose from FUNCTION, REPORTER
Default:FUNCTION
C++ Type:MooseEnum
Options:REPORTER, FUNCTION
Controllable:No
Description:choose from FUNCTION, REPORTER
growth_rateFunction defining crack growth rate
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function defining crack growth rate
growth_reporterThe name of the Reporter that computes the growth increment
C++ Type:ReporterName
Controllable:No
Description:The name of the Reporter that computes the growth increment
heal_alwaysFalseHeal previous cuts at every time step
Default:False
C++ Type:bool
Controllable:No
Description:Heal previous cuts at every time step
ki_vectorpostprocessorII_KI_1Name of the VectorPostprocessor that computes K_I
Default:II_KI_1
C++ Type:VectorPostprocessorName
Unit:(no unit assumed)
Controllable:No
Description:Name of the VectorPostprocessor that computes K_I
kii_vectorpostprocessorII_KII_1The name of the vectorpostprocessor that contains KII
Default:II_KII_1
C++ Type:VectorPostprocessorName
Unit:(no unit assumed)
Controllable:No
Description:The name of the vectorpostprocessor that contains KII
mesh_generator_nameMesh generator for the XFEM geometric cutter.
C++ Type:std::string
Controllable:No
Description:Mesh generator for the XFEM geometric cutter.
min_elem_area1e-06Growth elements smaller than min_elem_area will not be added.
Default:1e-06
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Growth elements smaller than min_elem_area will not be added.
n_step_growth0Number of steps for crack growth
Default:0
C++ Type:unsigned int
Controllable:No
Description:Number of steps for crack growth
size_control0Criterion for refining elements while growing the crack
Default:0
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Criterion for refining elements while growing the crack

Optional Parameters

allow_duplicate_execution_on_initialFalseIn the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
Default:False
C++ Type:bool
Controllable:No
Description:In the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
execute_onXFEM_MARKThe list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
Default:XFEM_MARK
C++ Type:ExecFlagEnum
Options:XFEM_MARK, FORWARD, ADJOINT, HOMOGENEOUS_FORWARD, ADJOINT_TIMESTEP_BEGIN, ADJOINT_TIMESTEP_END, NONE, INITIAL, LINEAR, LINEAR_CONVERGENCE, NONLINEAR, NONLINEAR_CONVERGENCE, POSTCHECK, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, MULTIAPP_FIXED_POINT_CONVERGENCE, FINAL, CUSTOM, TRANSFER
Controllable:No
Description:The list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
execution_order_group1Execution order groups are executed in increasing order (e.g., the lowest number is executed first). Note that negative group numbers may be used to execute groups before the default (0) group. Please refer to the user object documentation for ordering of user object execution within a group.
Default:1
C++ Type:int
Controllable:No
Description:Execution order groups are executed in increasing order (e.g., the lowest number is executed first). Note that negative group numbers may be used to execute groups before the default (0) group. Please refer to the user object documentation for ordering of user object execution within a group.
force_postauxFalseForces the UserObject to be executed in POSTAUX
Default:False
C++ Type:bool
Controllable:No
Description:Forces the UserObject to be executed in POSTAUX
force_preauxFalseForces the UserObject to be executed in PREAUX
Default:False
C++ Type:bool
Controllable:No
Description:Forces the UserObject to be executed in PREAUX
force_preicFalseForces the UserObject to be executed in PREIC during initial setup
Default:False
C++ Type:bool
Controllable:No
Description:Forces the UserObject to be executed in PREIC during initial setup

Execution Scheduling Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Controllable:Yes
Description:Set the enabled status of the MooseObject.
implicitTrueDetermines whether this object is calculated using an implicit or explicit form
Default:True
C++ Type:bool
Controllable:No
Description:Determines whether this object is calculated using an implicit or explicit form
seed0The seed for the master random number generator
Default:0
C++ Type:unsigned int
Controllable:No
Description:The seed for the master random number generator
use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.
Default:False
C++ Type:bool
Controllable:No
Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

Advanced Parameters

prop_getter_suffixAn optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
C++ Type:MaterialPropertyName
Unit:(no unit assumed)
Controllable:No
Description:An optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
use_interpolated_stateFalseFor the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.
Default:False
C++ Type:bool
Controllable:No
Description:For the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.

Material Property Retrieval Parameters

Input Files

(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_mhs.i)
(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_fatigue.i)
(modules/xfem/test/tests/solid_mechanics_basic/face_crack_3d_xfem_function.i)
(modules/xfem/test/tests/solid_mechanics_basic/face_crack_3d_xfem_scc.i)
(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_scc_crit.i)
(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_scc.i)
(modules/xfem/test/tests/solid_mechanics_basic/face_crack_3d_xfem_radialFunc.i)
(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_propagation.i)
(modules/xfem/test/tests/solid_mechanics_basic/face_crack_3d_xfem_hoopStress.i)
(modules/xfem/test/tests/solid_mechanics_basic/double_cantilever_crack.i)

(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_domain.i)

[GlobalParams]
  displacements = 'disp_x disp_y disp_z'
  volumetric_locking_correction = true
[]

[XFEM]
  geometric_cut_userobjects = 'cut_mesh'
  qrule = volfrac
  output_cut_plane = true
[]

[Mesh]
  [read_in_cutter_mesh]
    type = FileMeshGenerator
    file = mesh_edge_crack.xda
    save_with_name = mesh_cutter
  []
  [FEM_mesh]
    type = GeneratedMeshGenerator
    dim = 3
    nx = 5
    ny = 5
    nz = 2
    xmin = 0.0
    xmax = 1.0
    ymin = 0.0
    ymax = 1.0
    zmin = 0.0
    zmax = 0.2
    elem_type = HEX8
  []
  final_generator = FEM_mesh
[]

[Physics/SolidMechanics/QuasiStatic]
  [all]
    strain = FINITE
    add_variables = true
    generate_output = 'stress_xx stress_yy stress_zz vonmises_stress'
  []
[]

[BCs]
  [top_x]
    type = FunctionNeumannBC
    boundary = top
    variable = disp_x
    function = top_trac_x
  []
  [top_y]
    type = FunctionNeumannBC
    boundary = top
    variable = disp_y
    function = top_trac_y
  []
  [bottom_x]
    type = DirichletBC
    boundary = bottom
    variable = disp_x
    value = 0.0
  []
  [bottom_y]
    type = DirichletBC
    boundary = bottom
    variable = disp_y
    value = 0.0
  []
  [bottom_z]
    type = DirichletBC
    boundary = bottom
    variable = disp_z
    value = 0.0
  []
[]

[Materials]
  [elasticity_tensor]
    type = ComputeIsotropicElasticityTensor
    youngs_modulus = 207000
    poissons_ratio = 0.3
    block = 0
  []
  [stress]
    type = ComputeFiniteStrainElasticStress
    block = 0
  []
[]

[Executioner]
  type = Transient

  solve_type = 'PJFNK'
  petsc_options_iname = '-ksp_gmres_restart -pc_type -pc_hypre_type -pc_hypre_boomeramg_max_iter'
  petsc_options_value = '201                hypre    boomeramg      8'

  line_search = 'none'

  [Predictor]
    type = SimplePredictor
    scale = 1.0
  []

  # controls for linear iterations
  l_max_its = 100
  l_tol = 1e-2

  # controls for nonlinear iterations
  nl_max_its = 15
  nl_rel_tol = 1e-12
  nl_abs_tol = 1e-10

  # time control
  start_time = 0.0
  dt = 1.0
  end_time = 4.0
  max_xfem_update = 1
[]

[Outputs]
  execute_on = 'timestep_end'
  exodus = true
[]

(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_mhs.i)

[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = mesh_cutter
    growth_dir_method = MAX_HOOP_STRESS
    size_control = 1
    n_step_growth = 1
    growth_rate = growth_func_v
  []
[]

[DomainIntegral]
  integrals = 'Jintegral InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y disp_z'
  crack_front_points_provider = cut_mesh
  number_points_from_provider = 4
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.15'
  radius_outer = '0.45'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  block = 0
  incremental = true
[]

# function for CrackMeshCut3DUserObject crack
[Functions]
  [growth_func_v]
    type = ParsedFunction
    expression = 0.15
  []
[]

#function for BC on top surface
[Functions]
  [top_trac_x]
    type = ConstantFunction
    value = 100
  []
  [top_trac_y]
    type = ConstantFunction
    value = 100
  []
[]

[Outputs]
  file_base = edge_crack_3d_mhs_out
  [xfemcutter]
    type = XFEMCutMeshOutput
    xfem_cutter_uo = cut_mesh
  []
[]

(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_mhs.i)

[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = mesh_cutter
    growth_dir_method = MAX_HOOP_STRESS
    size_control = 1
    n_step_growth = 1
    growth_rate = growth_func_v
  []
[]

[DomainIntegral]
  integrals = 'Jintegral InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y disp_z'
  crack_front_points_provider = cut_mesh
  number_points_from_provider = 4
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.15'
  radius_outer = '0.45'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  block = 0
  incremental = true
[]

# function for CrackMeshCut3DUserObject crack
[Functions]
  [growth_func_v]
    type = ParsedFunction
    expression = 0.15
  []
[]

#function for BC on top surface
[Functions]
  [top_trac_x]
    type = ConstantFunction
    value = 100
  []
  [top_trac_y]
    type = ConstantFunction
    value = 100
  []
[]

[Outputs]
  file_base = edge_crack_3d_mhs_out
  [xfemcutter]
    type = XFEMCutMeshOutput
    xfem_cutter_uo = cut_mesh
  []
[]

(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_fatigue.i)

[Reporters]
  [fatigue]
    type = ParisLaw
    growth_increment_name = "growth_increment"
    cycles_to_max_growth_increment_name = "fatigue"
    crackMeshCut3DUserObject_name = cut_mesh
    max_growth_increment = 0.1001
    paris_law_c = 1e-13
    paris_law_m = 2.5
  []
[]

[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = mesh_cutter
    growth_dir_method = FUNCTION
    size_control = 1
    n_step_growth = 1
    growth_increment_method = REPORTER
    growth_direction_x = growth_func_x
    growth_direction_y = growth_func_y
    growth_direction_z = growth_func_z
    growth_reporter = "fatigue/growth_increment"
  []
[]

[DomainIntegral]
  integrals = 'Jintegral InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y disp_z'
  crack_front_points_provider = cut_mesh
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.15'
  radius_outer = '0.45'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  block = 0
  incremental = true
[]

# function for CrackMeshCut3DUserObject crack
[Functions]
  [growth_func_x]
    type = ParsedFunction
    expression = 1
  []
  [growth_func_y]
    type = ParsedFunction
    expression = 0
  []
  [growth_func_z]
    type = ParsedFunction
    expression = 0
  []
[]

#functino for BC on top surface
[Functions]
  [top_trac_y]
    type = ConstantFunction
    value = 10
  []
  [top_trac_x]
    type = ConstantFunction
    value = 0
  []
[]

[Outputs]
  file_base = edge_crack_3d_fatigue_out
[]

(modules/xfem/test/tests/solid_mechanics_basic/face_crack_3d_xfem_function.i)


[XFEM]
  geometric_cut_userobjects = 'cut_mesh'
  qrule = volfrac
  output_cut_plane = true
[]

[Functions]
  [growth_func_x]
    type = ParsedFunction
    expression = '0.2*(x-${offset})/abs(${rad})'
  []
  [growth_func_y]
    type = ParsedFunction
    expression = 0.0
  []
  [growth_func_z]
    type = ParsedFunction
    expression = 'if(t<3,0,0.1)'
  []
  [growth_func_v]
    type = ParsedFunction
    expression = 'if(t<3,0.02,0.015)'
  []
[]

[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = mesh_cutter
    growth_dir_method = FUNCTION
    growth_direction_x = growth_func_x
    growth_direction_y = growth_func_y
    growth_direction_z = growth_func_z
    size_control = .05
    n_step_growth = 1
    growth_rate = growth_func_v
  []
[]

[Outputs]
  file_base = face_crack_function_off_${offset}_spin_${spin}
  [xfemcutter]
    type = XFEMCutMeshOutput
    xfem_cutter_uo = cut_mesh
  []
  execute_on=final
[]

(modules/xfem/test/tests/solid_mechanics_basic/face_crack_3d_xfem_scc.i)


[XFEM]
  geometric_cut_userobjects = 'cut_mesh'
  qrule = volfrac
  output_cut_plane = false
[]

[Reporters]
  [scc_crack_growth]
    type = StressCorrosionCrackingExponential
    growth_increment_name = "crack_growth"
    time_to_max_growth_increment_name = "max_growth_timestep"
    crackMeshCut3DUserObject_name = cut_mesh
    max_growth_increment = 0.02
    k_low = 10
    k_high = 20
    growth_rate_mid_multiplier = 0.00075
    growth_rate_mid_exp_factor = 1
  []
[]

[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = mesh_cutter
    growth_dir_method = MAX_HOOP_STRESS
    size_control = .05
    n_step_growth = 1
    growth_increment_method = REPORTER
    growth_reporter = "scc_crack_growth/crack_growth"
  []
[]

[DomainIntegral]
  integrals = 'Jintegral InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y disp_z'
  crack_front_points_provider = cut_mesh
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.025'
  radius_outer = '0.1'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  incremental = false
[]

[Outputs]
  file_base = face_crack_scc_off_${offset}_spin_${spin}
  [xfemcutter]
    type = XFEMCutMeshOutput
    xfem_cutter_uo = cut_mesh
  []
  execute_on=final
[]

(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_scc_crit.i)

# This takes 1 step of max_growth_increment and back computes a time of 11s which
# is the amount of time edge_crack_3d_scc.i takes to grow a crack of similar length.

[Reporters]
  [scc_crack_growth]
    type = StressCorrosionCrackingExponential
    growth_increment_name = "crack_growth"
    time_to_max_growth_increment_name = "max_growth_timestep"
    crackMeshCut3DUserObject_name = cut_mesh
    max_growth_increment = 0.1
    k_low = 10
    k_high = 20
    growth_rate_mid_multiplier = 0.00075
    growth_rate_mid_exp_factor = 1
  []
[]
[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = mesh_cutter
    growth_dir_method = MAX_HOOP_STRESS
    size_control = 1
    n_step_growth = 1
    growth_increment_method = REPORTER
    growth_reporter = "scc_crack_growth/crack_growth"
  []
[]

[DomainIntegral]
  integrals = 'Jintegral InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y disp_z'
  crack_front_points_provider = cut_mesh
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.15'
  radius_outer = '0.45'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  block = 0
  incremental = true
[]

#function for BC on top surface
[Functions]
  [top_trac_y]
    type = ConstantFunction
    value = 10
  []
  [top_trac_x]
    type = ConstantFunction
    value = 0
  []
[]

[Outputs]
  file_base = edge_crack_3d_scc_crit_out
  execute_on = 'FINAL'
  [json_out]
    type = JSON
    execute_system_information_on = none
  []
[]

(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_scc.i)


# This takes 11 constant time steps and produces a crack size of the
# same length as edge_crack_3d_scc_crit after 1 step.
[Postprocessors]
  [dt]
    type = TimestepSize
  []
[]
[Reporters]
  [scc_crack_growth]
    type = ParsedVectorReporter
    name = crack_growth
    vector_reporter_names = 'II_KI_1/II_KI_1'
    vector_reporter_symbols = 'ki'
    scalar_reporter_names = 'dt/value'
    scalar_reporter_symbols = 'dt'
    constant_names = 'constant1 constant2'
    constant_expressions = '10 20'
    expression = 'if(ki<10,0.0075*dt,if(ki>20,0.015*dt,(0.00075*ki)*dt ))'
    execute_on = 'XFEM_MARK TIMESTEP_END'
  []
[]
[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = mesh_cutter
    growth_dir_method = MAX_HOOP_STRESS
    size_control = 1
    n_step_growth = 1
    growth_increment_method = REPORTER
    growth_reporter = "scc_crack_growth/crack_growth"
  []
[]

[DomainIntegral]
  integrals = 'Jintegral InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y disp_z'
  crack_front_points_provider = cut_mesh
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.15'
  radius_outer = '0.45'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  block = 0
  incremental = true
[]

#functino for BC on top surface
[Functions]
  [top_trac_y]
    type = ConstantFunction
    value = 10
  []
  [top_trac_x]
    type = ConstantFunction
    value = 0
  []
[]

[Outputs]
  file_base = edge_crack_3d_scc_out
  execute_on = 'FINAL'
  [csv_out]
    type = CSV
  []
[]

(modules/xfem/test/tests/solid_mechanics_basic/face_crack_3d_xfem_radialFunc.i)


[XFEM]
  geometric_cut_userobjects = 'cut_mesh'
  qrule = volfrac
  output_cut_plane = false
[]

[Functions]
  [growth_func_x]
    type = ParsedFunction
    expression = '(x-${offset})/sqrt((x-${offset})^2 + z^2)'
  []
  [growth_func_y]
    type = ParsedFunction
    expression = 0.0
  []
  [growth_func_z]
    type = ParsedFunction
    expression = 'z/sqrt((x-${offset})^2 + z^2)'
  []
  [growth_func_v]
    type = ParsedFunction
    expression = '.02'
  []
[]

[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = mesh_cutter
    growth_dir_method = FUNCTION
    growth_direction_x = growth_func_x
    growth_direction_y = growth_func_y
    growth_direction_z = growth_func_z
    size_control = .05
    n_step_growth = 1
    growth_rate = growth_func_v
  []
[]

[Outputs]
  file_base=${fname}_offset_${offset}_spin_${spin}
  [xfemcutter]
    type = XFEMCutMeshOutput
    xfem_cutter_uo = cut_mesh
  []
  execute_on=final
[]

(modules/xfem/test/tests/solid_mechanics_basic/edge_crack_3d_propagation.i)

[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_file = mesh_edge_crack.xda
    growth_dir_method = FUNCTION
    size_control = 0.1
    n_step_growth = 1
    growth_direction_x = growth_func_x
    growth_direction_y = growth_func_y
    growth_direction_z = growth_func_z
    growth_rate = growth_func_v
  []
[]

# function for CrackMeshCut3DUserObject crack
[Functions]
  [growth_func_x]
    type = ParsedFunction
    expression = 1
  []
  [growth_func_y]
    type = ParsedFunction
    expression = 0
  []
  [growth_func_z]
    type = ParsedFunction
    expression = 0
  []
  [growth_func_v]
    type = ParsedFunction
    expression = 0.15
  []
[]

#functino for BC on top surface
[Functions]
  [top_trac_y]
    type = ConstantFunction
    value = 10
  []
  [top_trac_x]
    type = ConstantFunction
    value = 0
  []
[]

[Outputs]
  file_base = edge_crack_3d_propagation_out
[]

(modules/xfem/test/tests/solid_mechanics_basic/face_crack_3d_xfem_hoopStress.i)


[XFEM]
  geometric_cut_userobjects = 'cut_mesh'
  qrule = volfrac
  output_cut_plane = false
[]

[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = mesh_cutter
    growth_dir_method = MAX_HOOP_STRESS
    size_control = .05
    n_step_growth = 1
    growth_rate = 0.02
  []
[]

[DomainIntegral]
  integrals = 'Jintegral InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y disp_z'
  crack_front_points_provider = cut_mesh
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.025'
  radius_outer = '0.1'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  incremental = false
[]

[Outputs]
  file_base = face_crack_hoopStress_off_${offset}_spin_${spin}
  [xfemcutter]
    type = XFEMCutMeshOutput
    xfem_cutter_uo = cut_mesh
  []
  execute_on=FINAL
[]

(modules/xfem/test/tests/solid_mechanics_basic/double_cantilever_crack.i)

# 3D Double Cantiler beam example.
# Figure 9 in: Belytschko and Black (1999)
# https://doi.org/10.1002/(SICI)1097-0207(19990620)45:5<601::AID-NME598>3.0.CO;2-S

# to reproduce literature results the mesh must be refined, in addition to using smaller fracture domain integral radii and smaller crack growth increments
# search comments for "to reproduce literature use"

L = 11.8
H = 3.94
W = 4
poissons = 0.3
youngs = 3e7
a = 3.94
da = 0.3
dtheta = 5.71 # 1.43, 2.86, 5.71

[GlobalParams]
  displacements = 'disp_x disp_y disp_z'
  volumetric_locking_correction = true
[]

[XFEM]
  geometric_cut_userobjects = 'cut_mesh'
  qrule = volfrac
  output_cut_plane = true
[]

[Mesh]
  [cut_profile]
    type = PolyLineMeshGenerator
    loop = false
    points = '-0.01 0 -2.01
              ${a} 0 -2.01
              ${fparse a+da*cos(dtheta*pi/180)} ${fparse da*sin(dtheta*pi/180)} -2.01'
  []
  [cut_surfaace]
    type = AdvancedExtruderGenerator
    input = cut_profile
    direction = '0 0 1'
    heights = '4.02'
    num_layers = '3'
    biases = '1'
  []
  [tri]
    type = ElementsToSimplicesConverter
    input = cut_surfaace
    save_with_name = cut_mesh
  []

  [gen]
    type = GeneratedMeshGenerator
    dim = 3
    nx = 30 # to reproduce literature use 240
    ny = 11 # to reproduce literature use 81
    nz = 4 # to reproduce literature use 10
    xmin = 0
    xmax = ${L}
    ymin = '-${fparse H/2}'
    ymax = '${fparse H/2}'
    zmin = '-${fparse W/2}'
    zmax = '${fparse W/2}'
    elem_type = HEX8
  []
  [bottom_left_elem]
    type = ParsedGenerateSideset
    input = gen
    combinatorial_geometry = 'x < 0.21'
    normal = '0 -1 0'
    include_only_external_sides=true
    new_sideset_name = bottom_left_elem
  []
  [top_left_elem]
    type = ParsedGenerateSideset
    input = bottom_left_elem
    combinatorial_geometry = 'x < 0.21'
    normal = '0 1 0'
    include_only_external_sides=true
    new_sideset_name = top_left_elem
  []
  final_generator = 'top_left_elem'
[]

[Functions]
  [growth_func_v]
    type = ParsedFunction
    expression = 0.21 # to reproduce literature use 0.0125
  []
[]
[UserObjects]
  [cut_mesh]
    type = CrackMeshCut3DUserObject
    mesh_generator_name = 'cut_mesh'
    growth_dir_method = MAX_HOOP_STRESS
    size_control = 1
    n_step_growth = 1
    growth_rate = growth_func_v
  []
[]

[DomainIntegral]
  integrals = 'Jintegral InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y disp_z'
  crack_front_points_provider = cut_mesh
  crack_direction_method = CurvedCrackFront
  radius_inner = 0.42 # to reproduce literature use 0.1
  radius_outer = 1.0 # to reproduce literature use 0.3
  poissons_ratio = ${poissons}
  youngs_modulus = ${youngs}
  incremental = false
[]

[Physics/SolidMechanics/QuasiStatic]
  [all]
    strain = SMALL
    incremental = false
    generate_output = 'stress_xx stress_yy stress_zz vonmises_stress max_principal_stress'
    add_variables = true
  []
[]

[BCs]
  [right_x]
    type = DirichletBC
    boundary = 'right'
    variable = disp_x
    value = 0
  []
  [right_y]
    type = DirichletBC
    boundary = 'right'
    variable = disp_y
    value = 0
  []
  [right_z]
    type = DirichletBC
    boundary = 'right'
    variable = disp_z
    value = 0
  []
  [planar_z]
    type = DirichletBC
    boundary = 'front back'
    variable = disp_z
    value = 0
  []
  [bottom_left_elem_y]
    type = NeumannBC
    boundary = 'bottom_left_elem'
    variable = disp_y
    value = -1000
  []
  [top_left_elem_y]
    type = NeumannBC
    boundary = 'top_left_elem'
    variable = disp_y
    value = 1000
  []
[]

[Materials]
  [elasticity_tensor]
    type = ComputeIsotropicElasticityTensor
    youngs_modulus = ${youngs}
    poissons_ratio = ${poissons}
  []
  [stress]
    type = ComputeLinearElasticStress
  []
[]

[Executioner]
  type = Transient
  solve_type = 'NEWTON'
  petsc_options_iname = '-pc_type -pc_hypre_type -ksp_gmres_restart'
  petsc_options_value = 'hypre boomeramg 31'
  # petsc_options_iname = '-pc_type -pc_factor_mat_solver_package -pc_factor_shift_type -pc_factor_shift_amount'
  # petsc_options_value = ' lu       superlu_dist                 NONZERO               1e-20'
  line_search = 'none'
  nl_abs_tol = 1e-7
  dt = 1.0
  end_time = 8 # to reproduce literature use 100
  max_xfem_update = 1
[]

[Outputs]
  csv = true
  execute_on=final
[]

Overview
Surface - Cutting Segment , Active and Inactive Nodes
Motion of the Inactive Node
Example Input Syntax
Input Parameters
Input Files