MeshCut2DFunctionUserObject

Creates a UserObject for a mesh cutter in 2D problems where crack growth is specified by functions.

Overview

This class is used to define an evolving cutting plane for 2D XFEM simulations based on a mesh that defines an initial crack, and a user-defined function for growth of that crack. It (1) reads in a mesh describing the crack surface, (2) uses the mesh to do initial cutting of 2D elements, and (3) grows the mesh incrementally based on prescribed growth functions defining the direction and growth rate.

Example Input Syntax

The [Mesh] block creating the simulation domain and cutter mesh is shown in Listing 2. This mesh block creates two seperate meshes. The simulation mesh is specified by "final_generator"=dispBlock. The cutter mesh is created in the [cutter_mesh] and [move_cutter_mesh] blocks. The final mesh cutter block [move_cutter_mesh] gives the cutter mesh a name using "save_with_name" which enables the MeshCut2DFractureUserObject shown in Listing 1 to specify this mesh with "mesh_generator_name".

Listing 1: MeshCut2DFractureUserObject userobject using the cutter mesh created by the [Mesh] block in Listing 2.

[UserObjects<<<{"href": "../../syntax/UserObjects/index.html"}>>>]
  [cut_mesh2]
    type = MeshCut2DFunctionUserObject<<<{"description": "Creates a UserObject for a mesh cutter in 2D problems where crack growth is specified by functions.", "href": "MeshCut2DFunctionUserObject.html"}>>>
    mesh_generator_name<<<{"description": "Mesh generator for the XFEM geometric cutter."}>>> = mesh_cutter
    growth_direction_x<<<{"description": "Function defining x-component of crack growth direction."}>>> = growth_func_x
    growth_direction_y<<<{"description": "Function defining y-component of crack growth direction."}>>> = growth_func_y
    growth_rate<<<{"description": "Function defining crack growth rate."}>>> = growth_func_v
    crack_front_definition<<<{"description": "The CrackFrontDefinition user object name"}>>> = crack_tip
  []
  [crack_tip]
    type = CrackFrontDefinition<<<{"description": "Used to describe geometric characteristics of the crack front for fracture integral calculations", "href": "CrackFrontDefinition.html"}>>>
    crack_direction_method<<<{"description": "Method to determine direction of crack propagation.  Choices are: CrackDirectionVector CrackMouth CurvedCrackFront"}>>> = CurvedCrackFront
    2d<<<{"description": "Treat body as two-dimensional"}>>> = true
    crack_front_points_provider<<<{"description": "The UserObject provides the crack front points from XFEM GeometricCutObject"}>>> = cut_mesh2
    number_points_from_provider<<<{"description": "The number of crack front points, only needed if crack_front_points_provider is used."}>>> = 2
  []
[]

Listing 2: [Mesh] block to create the simulation and cutter meshes.

[Mesh<<<{"href": "../../syntax/Mesh/index.html"}>>>]
  [cutter_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"}>>> = 1
    nx<<<{"description": "Number of elements in the X direction"}>>> = 2
    xmin<<<{"description": "Lower X Coordinate of the generated mesh"}>>> = -0.301
    xmax<<<{"description": "Upper X Coordinate of the generated mesh"}>>> = 0.301
  []
  [move_cutter_mesh]
    type = TransformGenerator<<<{"description": "Applies a linear transform to the entire mesh.", "href": "../meshgenerators/TransformGenerator.html"}>>>
    transform<<<{"description": "The type of transformation to perform (TRANSLATE, TRANSLATE_CENTER_ORIGIN, TRANSLATE_MIN_ORIGIN, ROTATE, SCALE)"}>>> = TRANSLATE
    vector_value<<<{"description": "The value to use for the transformation. When using TRANSLATE or SCALE, the xyz coordinates are applied in each direction respectively. When using ROTATE, the values are interpreted as the Euler angles phi, theta and psi given in degrees."}>>> = '0 0.5 0'
    input<<<{"description": "The mesh we want to modify"}>>> = cutter_mesh
    save_with_name<<<{"description": "Keep the mesh from this mesh generator in memory with the name specified"}>>> = mesh_cutter
  []
  [gen]
    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"}>>> = 2
    nx<<<{"description": "Number of elements in the X direction"}>>> = 45
    ny<<<{"description": "Number of elements in the Y direction"}>>> = 15
    xmin<<<{"description": "Lower X Coordinate of the generated mesh"}>>> = -1
    xmax<<<{"description": "Upper X Coordinate of the generated mesh"}>>> = 0.49
    ymin<<<{"description": "Lower Y Coordinate of the generated mesh"}>>> = 0.0
    ymax<<<{"description": "Upper Y Coordinate of the generated mesh"}>>> = 1.0
    elem_type<<<{"description": "The type of element from libMesh to generate (default: linear element for requested dimension)"}>>> = QUAD4
  []
  [dispBlock]
    type = BoundingBoxNodeSetGenerator<<<{"description": "Assigns all of the nodes either inside or outside of a bounding box to a new nodeset.", "href": "../meshgenerators/BoundingBoxNodeSetGenerator.html"}>>>
    new_boundary<<<{"description": "The name of the nodeset to create"}>>> = pull_set
    bottom_left<<<{"description": "The bottom left point (in x,y,z with spaces in-between) of the box to select the nodes."}>>> = '-0.1 0.99 0'
    top_right<<<{"description": "The bottom left point (in x,y,z with spaces in-between) of the box to select the nodes."}>>> = '0.1 1.01 0'
    input<<<{"description": "The mesh we want to modify"}>>> = gen
  []
  final_generator = dispBlock
[]

Input Parameters

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_rateFunction defining crack growth rate.
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:Function defining crack growth rate.

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
crack_front_definitioncrackFrontDefinitionThe CrackFrontDefinition user object name
Default:crackFrontDefinition
C++ Type:UserObjectName
Controllable:No
Description:The CrackFrontDefinition user object name
heal_alwaysFalseHeal previous cuts at every time step
Default:False
C++ Type:bool
Controllable:No
Description:Heal previous cuts at every time step
mesh_generator_nameMesh generator for the XFEM geometric cutter.
C++ Type:std::string
Controllable:No
Description:Mesh generator for the XFEM geometric cutter.
nucleate_uoThe MeshCutNucleation UO for nucleating cracks.
C++ Type:UserObjectName
Controllable:No
Description:The MeshCutNucleation UO for nucleating cracks.

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_group0Execution 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:0
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/mesh_cut_2D_fracture/crack_front_stress_function_growth.i)

(modules/xfem/test/tests/mesh_cut_2D_fracture/crack_front_stress_function_growth.i)

# checks that the stress averages computed by CrackFrontNonlocalStress are correct

# Left Crack Tip: moves in y with stress_11=y and crackFrontNormalStress is equal to y_pos+box_length/2
# At boundary when the crackFrontNormalStress box intersects the boundary, crackFrontNormalStress is properly scaled

# Right Crack Tip: moves at 45deg with stress_10&_01=y.  crackFrontNormalStress is equal to y_pos+box_length/sqrt(8)

[GlobalParams]
  displacements = 'disp_x disp_y'
[]

[Mesh]
  [cutter_mesh]
    type = GeneratedMeshGenerator
    dim = 1
    nx = 2
    xmin = -0.301
    xmax = 0.301
  []
  [move_cutter_mesh]
    type = TransformGenerator
    transform = TRANSLATE
    vector_value = '0 0.5 0'
    input = cutter_mesh
    save_with_name = mesh_cutter
  []
  [gen]
    type = GeneratedMeshGenerator
    dim = 2
    nx = 40
    ny = 14
    xmin = -0.4
    xmax = 0.5
    ymin = 0.4
    ymax = 0.65
    elem_type = QUAD4
  []
  final_generator = gen
[]

[Problem]
  solve = false
  kernel_coverage_check = false
[]

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

[Functions]
  [growth_func_x]
    type = ParsedFunction
    expression = 'if(x<0, 0, 1)'
  []
  [growth_func_y]
    type = ParsedFunction
    expression = 1
  []
  [growth_func_v]
    type = ParsedFunction
    expression = '0.05'
  []
[]

[UserObjects]
  [cut_mesh2]
    type = MeshCut2DFunctionUserObject
    mesh_generator_name = mesh_cutter
    growth_direction_x = growth_func_x
    growth_direction_y = growth_func_y
    growth_rate = growth_func_v
    crack_front_definition = crack_tip
  []
  [crack_tip]
    type = CrackFrontDefinition
    crack_direction_method = CurvedCrackFront
    2d = true
    crack_front_points_provider = cut_mesh2
    number_points_from_provider = 2
  []
[]

[AuxVariables]
  [disp_x]
    family = LAGRANGE
    order = FIRST
  []
  [disp_y]
    family = LAGRANGE
    order = FIRST
  []
[]

[Functions]
  [fcn_00]
    type = ParsedFunction
    expression = 'if(x<0,y,0)'
  []
  [fcn_10]
    type = ParsedFunction
    expression = 'if(x<0,0,y)'
  []
  [fcn_20]
    type = ParsedFunction
    expression = '0'
  []
  [fcn_11]
    type = ParsedFunction
    expression = '0'
  []
  [fcn_21]
    type = ParsedFunction
    expression = '0'
  []
  [fcn_22]
    type = ParsedFunction
    expression = '0'
  []
[]

[Materials]
  [tensor]
    type = GenericFunctionRankTwoTensor
    tensor_name = generic_stress
    # tensor values are column major-ordered
    tensor_functions = 'fcn_00 fcn_10 fcn_20  fcn_10 fcn_11 fcn_21  fcn_20 fcn_21 fcn_22'
    outputs = all
  []
[]

[VectorPostprocessors]
  [CrackFrontNonlocalStress]
    type = CrackFrontNonlocalStress
    base_name = generic
    stress_name = stress
    crack_front_definition = crack_tip
    box_length = 0.1
    box_height = 0.05
    box_width = 0.05
  []
[]

[Executioner]
  type = Transient
  start_time = 0.0
  dt = 1.0
  end_time = 4
[]

[Outputs]
  file_base = 'stress_check'
  csv = true
[]

(modules/xfem/test/tests/mesh_cut_2D_fracture/edge_crack_2d_propagation.i)

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

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

[Mesh]
  [cutter_mesh]
    type = GeneratedMeshGenerator
    dim = 1
    nx = 2
    xmin = -0.301
    xmax = 0.301
  []
  [move_cutter_mesh]
    type = TransformGenerator
    transform = TRANSLATE
    vector_value = '0 0.5 0'
    input = cutter_mesh
    save_with_name = mesh_cutter
  []
  [gen]
    type = GeneratedMeshGenerator
    dim = 2
    nx = 45
    ny = 15
    xmin = -1
    xmax = 0.49
    ymin = 0.0
    ymax = 1.0
    elem_type = QUAD4
  []
  [dispBlock]
    type = BoundingBoxNodeSetGenerator
    new_boundary = pull_set
    bottom_left = '-0.1 0.99 0'
    top_right = '0.1 1.01 0'
    input = gen
  []
  final_generator = dispBlock
[]

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

[Physics/SolidMechanics/QuasiStatic]
  [all]
    strain = SMALL
    incremental = true
    planar_formulation = plane_strain
    add_variables = true
    generate_output = 'stress_xx stress_yy'
  []
[]

[Functions]
  [pull_func]
    type = ParsedFunction
    expression = 0.00025*(1+t)
  []
[]

[BCs]
  [top_y]
    type = FunctionDirichletBC
    boundary = pull_set
    variable = disp_y
    function = pull_func
  []
  [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 = 'NEWTON'
  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
  [Predictor]
    type = SimplePredictor
    scale = 1.0
  []
  # time control
  start_time = 0.0
  dt = 1.0
  end_time = 3
  max_xfem_update = 100
[]

[Outputs]
  [xfemcutter]
    type = XFEMCutMeshOutput
    xfem_cutter_uo = cut_mesh2
  []
  [console]
    type = Console
    output_linear = false
    output_nonlinear = false
  []
[]

(modules/xfem/test/tests/mesh_cut_2D_fracture/crack_front_stress_function_growth.i)

# checks that the stress averages computed by CrackFrontNonlocalStress are correct

# Left Crack Tip: moves in y with stress_11=y and crackFrontNormalStress is equal to y_pos+box_length/2
# At boundary when the crackFrontNormalStress box intersects the boundary, crackFrontNormalStress is properly scaled

# Right Crack Tip: moves at 45deg with stress_10&_01=y.  crackFrontNormalStress is equal to y_pos+box_length/sqrt(8)

[GlobalParams]
  displacements = 'disp_x disp_y'
[]

[Mesh]
  [cutter_mesh]
    type = GeneratedMeshGenerator
    dim = 1
    nx = 2
    xmin = -0.301
    xmax = 0.301
  []
  [move_cutter_mesh]
    type = TransformGenerator
    transform = TRANSLATE
    vector_value = '0 0.5 0'
    input = cutter_mesh
    save_with_name = mesh_cutter
  []
  [gen]
    type = GeneratedMeshGenerator
    dim = 2
    nx = 40
    ny = 14
    xmin = -0.4
    xmax = 0.5
    ymin = 0.4
    ymax = 0.65
    elem_type = QUAD4
  []
  final_generator = gen
[]

[Problem]
  solve = false
  kernel_coverage_check = false
[]

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

[Functions]
  [growth_func_x]
    type = ParsedFunction
    expression = 'if(x<0, 0, 1)'
  []
  [growth_func_y]
    type = ParsedFunction
    expression = 1
  []
  [growth_func_v]
    type = ParsedFunction
    expression = '0.05'
  []
[]

[UserObjects]
  [cut_mesh2]
    type = MeshCut2DFunctionUserObject
    mesh_generator_name = mesh_cutter
    growth_direction_x = growth_func_x
    growth_direction_y = growth_func_y
    growth_rate = growth_func_v
    crack_front_definition = crack_tip
  []
  [crack_tip]
    type = CrackFrontDefinition
    crack_direction_method = CurvedCrackFront
    2d = true
    crack_front_points_provider = cut_mesh2
    number_points_from_provider = 2
  []
[]

[AuxVariables]
  [disp_x]
    family = LAGRANGE
    order = FIRST
  []
  [disp_y]
    family = LAGRANGE
    order = FIRST
  []
[]

[Functions]
  [fcn_00]
    type = ParsedFunction
    expression = 'if(x<0,y,0)'
  []
  [fcn_10]
    type = ParsedFunction
    expression = 'if(x<0,0,y)'
  []
  [fcn_20]
    type = ParsedFunction
    expression = '0'
  []
  [fcn_11]
    type = ParsedFunction
    expression = '0'
  []
  [fcn_21]
    type = ParsedFunction
    expression = '0'
  []
  [fcn_22]
    type = ParsedFunction
    expression = '0'
  []
[]

[Materials]
  [tensor]
    type = GenericFunctionRankTwoTensor
    tensor_name = generic_stress
    # tensor values are column major-ordered
    tensor_functions = 'fcn_00 fcn_10 fcn_20  fcn_10 fcn_11 fcn_21  fcn_20 fcn_21 fcn_22'
    outputs = all
  []
[]

[VectorPostprocessors]
  [CrackFrontNonlocalStress]
    type = CrackFrontNonlocalStress
    base_name = generic
    stress_name = stress
    crack_front_definition = crack_tip
    box_length = 0.1
    box_height = 0.05
    box_width = 0.05
  []
[]

[Executioner]
  type = Transient
  start_time = 0.0
  dt = 1.0
  end_time = 4
[]

[Outputs]
  file_base = 'stress_check'
  csv = true
[]

Overview
Example Input Syntax
Input Parameters
Input Files