MeshCut2DRankTwoTensorNucleation

Nucleate a crack in MeshCut2D UO based on a scalar extracted from a RankTwoTensor

Overview

The XFEM nucleation UserObject MeshCut2DRankTwoTensorNucleation defines new cracks that are added to the cutter mesh used by MeshCut2DFractureUserObject when a user-defined nucleation criterion is met. The nucleation criterion is based on the "scalar_type" extracted from a RankTwoTensor specified by "tensor" (used to store stresses and strains in SolidMechanics), such as a principal stress or a component of stress.

If the scalar exceeds a threshold specified by "nucleation_threshold", a line segment with a length specified by "nucleation_length" will be inserted into the MeshCut2DFractureUserObject cutter mesh. Cracks will nucleate on the domain interior or boundary. Crack nucleation can be limited to elements on boundaries specified by "initiate_on_boundary". Once the nucleation criterion is reached, a line segment of the specified length is inserted into the cutter mesh, centered on the element centroid it nucleates from. The direction of the nucleated crack is normal to the direction returned by the RankTwoTensor scalar. For example, MaxInPlanePrincipal returns the direction of the maximum in-plane principal component and the crack direction is normal to this. It is an error for "nucleation_length" to be smaller than the length of the element the crack nucleates in, unless the user sets nucleate_across_full_element=true. A crack will only be nucleated if it is at least a distance specified by "nucleation_radius" away from existing or nucleated cracks. If multiple cracks nucleate in the same xfem update and are within the specified nucleation_radius, the crack nucleated from the element with the lowest id will be retained and no other cracks within the nucleation_radius will be nucleated. The nucleation_radius is a good way to limit the number of cracks that nucleate within a region, which can help limit problems related to excessive numbers of XFEM cuts in a single element.

MeshCut2DRankTwoTensorNucleation copies several features available in the XFEMRankTwoTensorMarkerUserObject. These include the nucleation threshold being provided as a coupled variable and the computation of the maximum value of the scalar quantity used for nucleation. By providing the nucleation threshold as a coupled variable, it can be specified as either a constant or variable value. Coupled variable input is useful for introducing randomness in the strength by using an AuxVariable that has been initialized with a random initial condition. For example, the Volume Weighted Weibull initial condition is well-suited for this purpose. The determination of crack nucleation is based on the average value of the scalar quantity over all the quadrature points in an element.

Example Input File Syntax

[UserObjects<<<{"href": "../../syntax/UserObjects/index.html"}>>>]
  [nucleate]
    type = MeshCut2DRankTwoTensorNucleation<<<{"description": "Nucleate a crack in MeshCut2D UO based on a scalar extracted from a RankTwoTensor", "href": "MeshCut2DRankTwoTensorNucleation.html"}>>>
    tensor<<<{"description": "The material tensor name."}>>> = stress
    scalar_type<<<{"description": "Scalar quantity to be computed from tensor and used as a failure criterion"}>>> = MaxPrincipal
    nucleation_threshold<<<{"description": "Threshold for the scalar quantity of the RankTwoTensor to nucleate new cracks"}>>> = 180
    initiate_on_boundary<<<{"description": "Cracks can only initiate on elements adjacent to specified boundaries."}>>> = 'left'
    nucleation_radius<<<{"description": "Cracks will only nucleate if they are outside the nucleation_radius of an existing crack."}>>> = .21
    edge_extension_factor<<<{"description": "Factor by which the length of cracks that have been adjusted to coincide with element edges are increased to avoid missing an intersection with the edge due to numerical tolerance issues."}>>> = 2e-5
    nucleation_length<<<{"description": "Size of crack to nucleate.  Must be larger than the length of the element in which the crack is nucleated, unless 'nucleate_across_full_element' is set to 'true'."}>>> = 0.11
  []
[]

Input Parameters

nucleation_thresholdThreshold for the scalar quantity of the RankTwoTensor to nucleate new cracks
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:Threshold for the scalar quantity of the RankTwoTensor to nucleate new cracks
tensorThe material tensor name.
C++ Type:std::string
Controllable:No
Description:The material tensor name.

Required 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
edge_extension_factor1e-05Factor by which the length of cracks that have been adjusted to coincide with element edges are increased to avoid missing an intersection with the edge due to numerical tolerance issues.
Default:1e-05
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Factor by which the length of cracks that have been adjusted to coincide with element edges are increased to avoid missing an intersection with the edge due to numerical tolerance issues.
initiate_on_boundaryCracks can only initiate on elements adjacent to specified boundaries.
C++ Type:std::vector<BoundaryName>
Controllable:No
Description:Cracks can only initiate on elements adjacent to specified boundaries.
nucleate_across_full_elementFalseControls the behavior of nucleating cracks if 'nucleation_length' is smaller than the length required to travserse an element with a nucleating crack. If this is set to 'false', that condition will result in an error, but if set to 'true', a crack with the length needed to traverse the element will be inserted.
Default:False
C++ Type:bool
Controllable:No
Description:Controls the behavior of nucleating cracks if 'nucleation_length' is smaller than the length required to travserse an element with a nucleating crack. If this is set to 'false', that condition will result in an error, but if set to 'true', a crack with the length needed to traverse the element will be inserted.
nucleation_lengthSize of crack to nucleate. Must be larger than the length of the element in which the crack is nucleated, unless 'nucleate_across_full_element' is set to 'true'.
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Size of crack to nucleate. Must be larger than the length of the element in which the crack is nucleated, unless 'nucleate_across_full_element' is set to 'true'.
nucleation_radius0Cracks will only nucleate if they are outside the nucleation_radius of an existing crack.
Default:0
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Cracks will only nucleate if they are outside the nucleation_radius of an existing crack.
point10 0 0Start point for axis used to calculate some cylindrical material tensor quantities
Default:0 0 0
C++ Type:libMesh::Point
Controllable:No
Description:Start point for axis used to calculate some cylindrical material tensor quantities
point20 1 0End point for axis used to calculate some cylindrical material tensor quantities
Default:0 1 0
C++ Type:libMesh::Point
Controllable:No
Description:End point for axis used to calculate some cylindrical material tensor quantities
scalar_typeScalar quantity to be computed from tensor and used as a failure criterion
C++ Type:MooseEnum
Options:VonMisesStress, EffectiveStrain, Hydrostatic, L2norm, MaxPrincipal, MidPrincipal, MinPrincipal, VolumetricStrain, FirstInvariant, SecondInvariant, ThirdInvariant, AxialStress, HoopStress, RadialStress, TriaxialityStress, Direction, MaxShear, StressIntensity
Controllable:No
Description:Scalar quantity to be computed from tensor and used as a failure criterion

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
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_group-1Nucleation UO needs to be completely executed before GeometricCutUserObject.
Default:-1
C++ Type:int
Controllable:No
Description:Nucleation UO needs to be completely executed before GeometricCutUserObject.
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/nucleation_uo/nucleate_bulkCrack.i)
(modules/xfem/test/tests/nucleation_uo/nucleate_AllEdgeCracks.i)
(modules/xfem/test/tests/nucleation_uo/nucleate_edge_bulk_crack_2d.i)

(modules/xfem/test/tests/nucleation_uo/nucleate_AllEdgeCracks.i)

[GlobalParams]
  displacements = 'disp_x disp_y'
[]

[XFEM]
  geometric_cut_userobjects = 'cut_mesh2'
  qrule = volfrac
  output_cut_plane = true
[]

[Mesh]
[gen]
  type = GeneratedMeshGenerator
  dim = 2
  nx = 10
  ny = 20
  xmin = 0
  xmax = 1.0
  ymin = 0.0
  ymax = 2.0
  elem_type = QUAD4
[]
[top_left]
  type = BoundingBoxNodeSetGenerator
  new_boundary = pull_top_left
  bottom_left = '-0.01 1.99 0'
  top_right = '0.11 2.01 0'
  input = gen
[]
[]

[DomainIntegral]
  integrals = 'InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y'
  crack_front_points_provider = cut_mesh2
  2d=true
  number_points_from_provider = 0
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.15'
  radius_outer = '0.45'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  block = 0
  incremental = true
[]

[UserObjects]
  [nucleate]
    type = MeshCut2DRankTwoTensorNucleation
    tensor = stress
    scalar_type = MaxPrincipal
    nucleation_threshold = 180
    initiate_on_boundary = 'left'
    nucleation_radius = .21
    edge_extension_factor = 2e-5
    nucleation_length = 0.11
  []
  [cut_mesh2]
    type = MeshCut2DFractureUserObject
    mesh_file = make_edge_crack_in.e
    k_critical=500000 #Large so that cracks will not grow
    growth_increment = 0.11
    nucleate_uo = nucleate
  []
[]

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

[Functions]
  [bc_pull_top]
    type = ParsedFunction
    expression = 0.0005*t
  []
[]

[BCs]
  [top_edges]
      type = FunctionDirichletBC
      boundary = 'pull_top_left'
      variable = disp_y
      function = bc_pull_top
  []
  [bottom_x]
    type = DirichletBC
    boundary = bottom
    variable = disp_x
    value = 0.0
  []
  [bottom_y]
    type = DirichletBC
    boundary = bottom
    variable = disp_y
    value = 0.0
  []
[]

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

[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
  [../]

  l_max_its = 100
  l_tol = 1e-2

  nl_max_its = 15
  nl_rel_tol = 1e-8
  nl_abs_tol = 1e-9

  start_time = 0.0
  dt = 1.0
  end_time = 5
  max_xfem_update = 100
[]

[Outputs]
  csv=true
  execute_on = TIMESTEP_END
[]

(modules/xfem/test/tests/nucleation_uo/nucleate_bulkCrack.i)

[GlobalParams]
  displacements = 'disp_x disp_y'
[]

[XFEM]
  geometric_cut_userobjects = 'cut_mesh2'
  qrule = volfrac
  output_cut_plane = true
[]

[Mesh]
[gen]
  type = GeneratedMeshGenerator
  dim = 2
  nx = 10
  ny = 20
  xmin = 0
  xmax = 1.0
  ymin = 0.0
  ymax = 2.0
  elem_type = QUAD4
[]

[]

[DomainIntegral]
  integrals = 'InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y'
  crack_front_points_provider = cut_mesh2
  2d=true
  number_points_from_provider = 0
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.15'
  radius_outer = '0.45'
  poissons_ratio = 0.0
  youngs_modulus = 207000
  block = 0
  incremental = true
[]

[AuxVariables]
[strength]
  order = CONSTANT
  family = MONOMIAL
[]
[]

[ICs]
[strength]
  type = VolumeWeightedWeibull
  variable = strength
  reference_volume = 1e-2
  weibull_modulus = 1
  median = 5000
[]
[]

[UserObjects]
  [nucleate]
    type = MeshCut2DRankTwoTensorNucleation
    tensor = stress
    scalar_type = MaxPrincipal
    nucleation_threshold = strength
    nucleation_radius = .21
    edge_extension_factor = .1
  []
  [cut_mesh2]
    type = MeshCut2DFractureUserObject
    mesh_file = make_edge_crack_in.e
    k_critical=500000 #Large so that cracks will not grow
    growth_increment = 0.11
    nucleate_uo = nucleate
  []
[]

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

[Functions]
  [bc_pull_top]
    type = ParsedFunction
    expression = 0.0005*t
  []
[]

[BCs]
  [top_edges]
      type = FunctionDirichletBC
      boundary = 'top'
      variable = disp_y
      function = bc_pull_top
  []
  [bottom_x]
    type = DirichletBC
    boundary = bottom
    variable = disp_x
    value = 0.0
  []
  [bottom_y]
    type = DirichletBC
    boundary = bottom
    variable = disp_y
    value = 0.0
  []
[]

[Materials]
  [elasticity_tensor]
    type = ComputeIsotropicElasticityTensor
    youngs_modulus = 207000
    poissons_ratio = 0.0
  []
  [stress]
    type = ComputeFiniteStrainElasticStress
  []
[]

[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
  [../]

  l_max_its = 100
  l_tol = 1e-2

  nl_max_its = 15
  nl_rel_tol = 1e-8
  nl_abs_tol = 1e-9

  start_time = 0.0
  dt = 1.0
  end_time = 5
  max_xfem_update = 1
[]

[Outputs]
  csv=true
  execute_on = final
  # exodus=true
  # [xfemcutter]
  #   type=XFEMCutMeshOutput
  #   xfem_cutter_uo=cut_mesh2
  # []
[]

(modules/xfem/test/tests/nucleation_uo/nucleate_AllEdgeCracks.i)

[GlobalParams]
  displacements = 'disp_x disp_y'
[]

[XFEM]
  geometric_cut_userobjects = 'cut_mesh2'
  qrule = volfrac
  output_cut_plane = true
[]

[Mesh]
[gen]
  type = GeneratedMeshGenerator
  dim = 2
  nx = 10
  ny = 20
  xmin = 0
  xmax = 1.0
  ymin = 0.0
  ymax = 2.0
  elem_type = QUAD4
[]
[top_left]
  type = BoundingBoxNodeSetGenerator
  new_boundary = pull_top_left
  bottom_left = '-0.01 1.99 0'
  top_right = '0.11 2.01 0'
  input = gen
[]
[]

[DomainIntegral]
  integrals = 'InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y'
  crack_front_points_provider = cut_mesh2
  2d=true
  number_points_from_provider = 0
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.15'
  radius_outer = '0.45'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  block = 0
  incremental = true
[]

[UserObjects]
  [nucleate]
    type = MeshCut2DRankTwoTensorNucleation
    tensor = stress
    scalar_type = MaxPrincipal
    nucleation_threshold = 180
    initiate_on_boundary = 'left'
    nucleation_radius = .21
    edge_extension_factor = 2e-5
    nucleation_length = 0.11
  []
  [cut_mesh2]
    type = MeshCut2DFractureUserObject
    mesh_file = make_edge_crack_in.e
    k_critical=500000 #Large so that cracks will not grow
    growth_increment = 0.11
    nucleate_uo = nucleate
  []
[]

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

[Functions]
  [bc_pull_top]
    type = ParsedFunction
    expression = 0.0005*t
  []
[]

[BCs]
  [top_edges]
      type = FunctionDirichletBC
      boundary = 'pull_top_left'
      variable = disp_y
      function = bc_pull_top
  []
  [bottom_x]
    type = DirichletBC
    boundary = bottom
    variable = disp_x
    value = 0.0
  []
  [bottom_y]
    type = DirichletBC
    boundary = bottom
    variable = disp_y
    value = 0.0
  []
[]

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

[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
  [../]

  l_max_its = 100
  l_tol = 1e-2

  nl_max_its = 15
  nl_rel_tol = 1e-8
  nl_abs_tol = 1e-9

  start_time = 0.0
  dt = 1.0
  end_time = 5
  max_xfem_update = 100
[]

[Outputs]
  csv=true
  execute_on = TIMESTEP_END
[]

(modules/xfem/test/tests/nucleation_uo/nucleate_edge_bulk_crack_2d.i)

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

[XFEM]
  geometric_cut_userobjects = 'cut_mesh2'
  qrule = volfrac
  output_cut_plane = true
[]

[Mesh]
  [gen]
    type = GeneratedMeshGenerator
    dim = 2
    nx = 60
    ny = 10
    xmin = -3
    xmax = 3
    ymin = 0.0
    ymax = 1.0
    elem_type = QUAD4
  []
  [top_left]
    type = BoundingBoxNodeSetGenerator
    new_boundary = pull_top_left
    bottom_left = '-3.01 0.99 0'
    top_right = '-2.99 1.01 0'
    input = gen
  []
  [top_mid_left]
    type = BoundingBoxNodeSetGenerator
    new_boundary = pull_mid_left
    bottom_left = '-1.01 0.99 0'
    top_right = '-0.99 1.01 0'
    input = top_left
  []
  [top_mid_right]
    type = BoundingBoxNodeSetGenerator
    new_boundary = pull_mid_right
    bottom_left = '0.99 0.99 0'
    top_right = '1.01 1.01 0'
    input = top_mid_left
  []
  [top_right]
    type = BoundingBoxNodeSetGenerator
    new_boundary = pull_top_right
    bottom_left = '2.99 0.99 0'
    top_right = '3.01 1.01 0'
    input = top_mid_right
  []

  [top_mid_left_ss]
    type = SideSetsFromBoundingBoxGenerator
    input = top_right
    bottom_left = '-2.21 0.89 0'
    top_right = '-1.79 1.01 0'
    boundary_new = top_mid_left_ss
    boundaries_old = top
  []
  [top_mid_ss]
    type = SideSetsFromBoundingBoxGenerator
    input = top_mid_left_ss
    bottom_left = '-0.21 0.89 0'
    top_right = '0.21 1.01 0'
    boundary_new = top_mid_ss
    boundaries_old = top
  []
  [top_mid_right_ss]
    type = SideSetsFromBoundingBoxGenerator
    input = top_mid_ss
    bottom_left = '1.79 0.89 0'
    top_right = '2.21 1.01 0'
    boundary_new = top_mid_right_ss
    boundaries_old = top
  []

  [nucleation_strip]
    # strip in middle of domain where cracks can nucleate
    type = ParsedSubdomainMeshGenerator
    input = top_mid_right_ss
    combinatorial_geometry = 'y > 0.39 & y < 0.51'
    block_id = 10
  []
[]

[DomainIntegral]
  integrals = 'InteractionIntegralKI InteractionIntegralKII'
  displacements = 'disp_x disp_y'
  crack_front_points_provider = cut_mesh2
  2d = true
  number_points_from_provider = 0
  crack_direction_method = CurvedCrackFront
  radius_inner = '0.15'
  radius_outer = '0.45'
  poissons_ratio = 0.3
  youngs_modulus = 207000
  block = 0
  incremental = false
[]

[UserObjects]
  [nucleate]
    type = MeshCut2DRankTwoTensorNucleation
    tensor = stress
    scalar_type = MaxPrincipal
    nucleation_threshold = nucleation_threshold
    # initiate_on_boundary = 'left right'
    nucleation_radius = .41
    nucleation_length = 0.21
  []
  [cut_mesh2]
    type = MeshCut2DFractureUserObject
    mesh_file = make_edge_crack_in.e
    k_critical = 230
    growth_increment = 0.11
    nucleate_uo = nucleate
    execute_on = 'XFEM_MARK'
  []
[]
[AuxVariables]
  [nucleation_threshold]
    order = CONSTANT
    family = MONOMIAL
  []
[]
[ICs]
  [nucleation_bulk]
    type = ConstantIC
    value = 10000
    variable = nucleation_threshold
    block = 0
  []
  [nucleation_weak]
    type = FunctionIC
    function = nucleation_x
    variable = nucleation_threshold
    block = 10
  []
[]

[Functions]
  [nucleation_x]
    type = ParsedFunction
    expression = 'A*cos(pi*x)+D'
    symbol_names = 'A D'
    symbol_values = '100 200'
  []
[]

[Physics/SolidMechanics/QuasiStatic]
  [all]
    strain = SMALL
    planar_formulation = PLANE_STRAIN
    add_variables = true
  []
[]

[Functions]
  [bc_pull_edge]
    type = ParsedFunction
    expression = 0.0004*t
  []
  [bc_pull_mid]
    type = ParsedFunction
    expression = 0.0005*t
  []
[]

[BCs]
  [top_edge_nodes]
    type = FunctionDirichletBC
    boundary = 'pull_top_left pull_top_right'
    variable = disp_y
    function = bc_pull_edge
  []
  [top_mid_nodes]
    type = FunctionDirichletBC
    boundary = 'pull_mid_left pull_mid_right'
    variable = disp_y
    function = bc_pull_mid
  []
  # [top_middle]
  #   type = NeumannBC
  #   boundary = 'top_mid_left_ss top_mid_ss top_mid_right_ss'
  #   variable = disp_y
  #   value = -2000
  # []
  [top_middle]
    type = DirichletBC
    boundary = 'top_mid_left_ss top_mid_ss top_mid_right_ss'
    variable = disp_y
    value = 0
  []
  [bottom_x]
    type = DirichletBC
    boundary = bottom
    variable = disp_x
    value = 0.0
  []
  [bottom_y]
    type = DirichletBC
    boundary = bottom
    variable = disp_y
    value = 0.0
  []
[]

[Materials]
  [elasticity_tensor]
    type = ComputeIsotropicElasticityTensor
    youngs_modulus = 207000
    poissons_ratio = 0.3
  []
  [stress]
    type = ComputeLinearElasticStress
  []
[]

[Executioner]
  type = Transient

  solve_type = 'NEWTON'
  petsc_options_iname = '-ksp_type -pc_type -pc_factor_mat_solver_package'
  petsc_options_value = 'gmres lu superlu_dist'

  line_search = 'none'

  [Predictor]
    type = SimplePredictor
    scale = 1.0
  []

  reuse_preconditioner = true
  reuse_preconditioner_max_linear_its = 25

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

  # controls for nonlinear iterations
  nl_max_its = 15
  nl_rel_tol = 1e-8
  nl_abs_tol = 1e-9

  # time control
  start_time = 0.0
  dt = 1.0
  end_time = 10
  max_xfem_update = 100
[]

[Outputs]
  csv = true
  execute_on = FINAL
  # exodus = true
  # [xfemcutter]
  #   type = XFEMCutMeshOutput
  #   xfem_cutter_uo = cut_mesh2
  # []
  [console]
    type = Console
    output_linear = false
    output_nonlinear = false
  []
[]

Overview
Example Input File Syntax
Input Parameters
Input Files