MortarCZMDebondedBoundaryUpdater

Promotes fully-damaged CZM interface segments into new sidesets.

Description

MortarCZMDebondedBoundaryUpdater builds sidesets on the portions of a mortar cohesive zone interface that have fully debonded, so that loads such as a gas pressure can be applied to the walls of the void that opens between the two surfaces. As the cohesive zone damage evolves, every segment of the interface whose damage has reached a threshold value is added to two sidesets: the face on the secondary side is added to "debonded_boundary_secondary", and every face on the primary side that the secondary face was bonded to is added to "debonded_boundary_primary". Together the two sidesets bound the debonded region, so they both can be used to apply boundary conditions to the surfaces of the void created by debonding.

A segment is considered fully separated when the damage given by "damage_variable" is at or above "threshold" at every quadrature point of a secondary lower-dimensional element. The damage is normally provided by a CohesiveZoneMortarUserObjectAux with cohesive_zone_quantity = cohesive_damage. The default threshold is $var element = document.getElementById("moose-equation-535d728b-8342-4933-b0a2-97eac9c13e28");katex.render("1 - 10^{-10}", element, {displayMode:false,throwOnError:false,macros:{"\\eqc":"\\,,","\\eqp":"\\,.","\\pd":"\\frac{\\partial #1}{\\partial #2}","\\pr":"\\left(#1\\right)","\\ddt":"\\frac{d #1}{d t}"}});$ , so that only segments the cohesive zone model reports as fully broken are added; it is not intended as a tuning parameter.

The primary faces paired with each secondary face are those that overlapped it in the undisplaced configuration, determined once at the start of the simulation from a mortar projection between "secondary_boundary" and "primary_boundary". Pairing in the reference configuration ensures that the faces added to the two sidesets are a subset of the faces that were initially bonded together, regardless of how the surfaces may have opened or slid relative to each other. When the primary and secondary meshes do not conform, a secondary face may be paired with several primary faces, and all of them are added.

Faces are only ever added and never removed from the sidesets, because a debonded cohesive zone is assumed to not heal. The mesh is marked as changed only on time steps in which new faces are added, so that objects acting on the two sidesets, such as Pressure boundary conditions, are reinitialized to include the new faces. Because the sidesets are updated at the end of a time step, after the solve, a face that debonds during a time step is loaded by such boundary conditions from the next time step onward.

Example Input Syntax

[MeshModifiers<<<{"href": "../../syntax/MeshModifiers/index.html"}>>>]
  [pressure_sideset_updater]
    type = MortarCZMDebondedBoundaryUpdater<<<{"description": "Promotes fully-damaged CZM interface segments into new sidesets.", "href": "MortarCZMDebondedBoundaryUpdater.html"}>>>
    block<<<{"description": "The list of blocks (ids or names) that this object will be applied"}>>> = secondary_lower
    damage_variable<<<{"description": "CZM damage AuxVariable (0 = intact, 1 = fully broken), valid on the secondary lower-dimensional mortar block."}>>> = damage
    cohesive_zone_userobject<<<{"description": "The mortar cohesive-zone UserObject for this interface."}>>> = czm_uo
    primary_boundary<<<{"description": "Primary side of the CZM mortar interface."}>>> = upper_bottom
    secondary_boundary<<<{"description": "Secondary side of the CZM mortar interface."}>>> = lower_top
    primary_subdomain<<<{"description": "Primary lower-dimensional mortar block."}>>> = primary_lower
    secondary_subdomain<<<{"description": "Secondary lower-dimensional mortar block."}>>> = secondary_lower
    debonded_boundary_primary<<<{"description": "Boundary to populate with fully-damaged primary faces."}>>> = czm_pressure_primary
    debonded_boundary_secondary<<<{"description": "Boundary to populate with fully-damaged secondary faces."}>>> = czm_pressure_secondary
    execute_on<<<{"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."}>>> = TIMESTEP_END
    # Run before the default group so that the postprocessors see faces promoted this step
    execution_order_group<<<{"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."}>>> = -1
  []
[]

Input Parameters

cohesive_zone_userobjectThe mortar cohesive-zone UserObject for this interface.
C++ Type:UserObjectName
Controllable:No
Description:The mortar cohesive-zone UserObject for this interface.
damage_variableCZM damage AuxVariable (0 = intact, 1 = fully broken), valid on the secondary lower-dimensional mortar block.
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:CZM damage AuxVariable (0 = intact, 1 = fully broken), valid on the secondary lower-dimensional mortar block.
debonded_boundary_primaryBoundary to populate with fully-damaged primary faces.
C++ Type:BoundaryName
Controllable:No
Description:Boundary to populate with fully-damaged primary faces.
debonded_boundary_secondaryBoundary to populate with fully-damaged secondary faces.
C++ Type:BoundaryName
Controllable:No
Description:Boundary to populate with fully-damaged secondary faces.
primary_boundaryPrimary side of the CZM mortar interface.
C++ Type:BoundaryName
Controllable:No
Description:Primary side of the CZM mortar interface.
primary_subdomainPrimary lower-dimensional mortar block.
C++ Type:SubdomainName
Controllable:No
Description:Primary lower-dimensional mortar block.
secondary_boundarySecondary side of the CZM mortar interface.
C++ Type:BoundaryName
Controllable:No
Description:Secondary side of the CZM mortar interface.
secondary_subdomainSecondary lower-dimensional mortar block.
C++ Type:SubdomainName
Controllable:No
Description:Secondary lower-dimensional mortar block.

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
interface_boundariesThe interface boundaries on which this object will execute
C++ Type:std::vector<BoundaryName>
Controllable:No
Description:The interface boundaries on which this object will execute
threshold1Damage at or above which a face considered is fully separated.
Default:1
C++ Type:Real
Unit:(no unit assumed)
Controllable:No
Description:Damage at or above which a face considered is fully separated.

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_onTIMESTEP_ENDThe 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:TIMESTEP_END
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, MULTISYSTEM_FIXED_POINT_ITERATION_END, 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_meshTrueWhether 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:True
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/combined/test/tests/czm_pressure_sidesets/czm_pressure_sideset_cavity.i)
(modules/combined/test/tests/czm_pressure_sidesets/czm_pressure_sideset.i)

(modules/combined/test/tests/czm_pressure_sidesets/czm_pressure_sideset.i)

# Two blocks bonded by a mortar cohesive zone are peeled apart from x = 0, so the debonded region
# grows from left to right. Due to the model configuration, each secondary face overlaps one or two
# primary faces.
#
# As each secondary face fully separates, it must be added to czm_pressure_secondary, and every
# primary face it fully overlaps in the undisplaced configuration must be added to
# czm_pressure_primary. The length and first moment (integral of x) of each sideset record which
# faces it holds: a sideset holding the first k faces of width h from x = 0 has length k h and
# first moment (k h)^2 / 2. Once the whole interface has failed the blocks carry no load, so the
# void between the two sidesets must equal the integral of the prescribed opening,
# opening * t * (1 - x / 2), over x in [0, 1], which is 3 / 4 * opening * t.

opening = 0.1

[Mesh]
  # The interface lies on y = 0 and the upper block is not displaced in x, so the void integrand
  # -y n_y vanishes on the vertical closing segments at both ends of the void, which belong to
  # neither sideset.
  [lower]
    type = GeneratedMeshGenerator
    dim = 2
    xmax = 1
    ymin = -0.5
    ymax = 0
    nx = 4
    ny = 1
    boundary_name_prefix = lower
  []
  [lower_id]
    type = SubdomainIDGenerator
    input = lower
    subdomain_id = 1
  []
  [upper]
    type = GeneratedMeshGenerator
    dim = 2
    xmax = 1
    ymin = 0
    ymax = 0.5
    nx = 3
    ny = 1
    boundary_name_prefix = upper
    boundary_id_offset = 10
  []
  [upper_id]
    type = SubdomainIDGenerator
    input = upper
    subdomain_id = 2
  []
  [combined]
    type = MeshCollectionGenerator
    inputs = 'lower_id upper_id'
  []
  [secondary]
    type = LowerDBlockFromSidesetGenerator
    new_block_id = 10001
    new_block_name = secondary_lower
    sidesets = lower_top
    input = combined
  []
  [primary]
    type = LowerDBlockFromSidesetGenerator
    new_block_id = 10000
    new_block_name = primary_lower
    sidesets = upper_bottom
    input = secondary
  []

  add_sideset_names = 'czm_pressure_primary czm_pressure_secondary'
  add_sideset_ids = '1000 1001'
[]

[GlobalParams]
  displacements = 'disp_x disp_y'
[]

[Physics/SolidMechanics/QuasiStatic/all]
  strain = SMALL
  add_variables = true
  use_automatic_differentiation = true
  block = '1 2'
[]

[AuxVariables]
  [damage]
  []
[]

[AuxKernels]
  [damage]
    type = CohesiveZoneMortarUserObjectAux
    variable = damage
    user_object = czm_uo
    cohesive_zone_quantity = cohesive_damage
  []
[]

[BCs]
  [fix_x]
    type = DirichletBC
    boundary = lower_bottom
    variable = disp_x
    value = 0
  []
  [fix_y]
    type = DirichletBC
    boundary = lower_bottom
    variable = disp_y
    value = 0
  []
  [fix_upper_x]
    type = DirichletBC
    boundary = upper_top
    variable = disp_x
    value = 0
  []
  [peel_y]
    type = FunctionDirichletBC
    boundary = upper_top
    variable = disp_y
    function = '${opening} * t * (1 - x / 2)'
  []
[]

[Materials]
  [elasticity_tensor]
    type = ADComputeIsotropicElasticityTensor
    youngs_modulus = 1e9
    poissons_ratio = 0
    block = '1 2'
  []
  [stress]
    type = ADComputeLinearElasticStress
    block = '1 2'
  []
  [normal_strength]
    type = GenericConstantMaterial
    prop_names = normal_strength
    prop_values = 1e4
  []
  [shear_strength]
    type = GenericConstantMaterial
    prop_names = shear_strength
    prop_values = 1e4
  []
[]

[UserObjects]
  [czm_uo]
    type = BilinearMixedModeCohesiveZoneModel
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    disp_x = disp_x
    disp_y = disp_y
    secondary_variable = disp_x
    use_physical_gap = true
    correct_edge_dropping = true
    normal_strength = normal_strength
    shear_strength = shear_strength
    penalty_stiffness = 1e12
    power_law_parameter = 2
    # Fully separated (damage = 1) once the opening exceeds 2 GI_c / normal_strength = 4e-2, which
    # is much larger than the 1e-5 elastic stretch of the blocks at peak traction, so the response
    # does not snap back
    GI_c = 200
    GII_c = 200
  []
[]

[Constraints]
  [x]
    type = NormalMortarMechanicalContact
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_x
    component = x
    use_displaced_mesh = true
    compute_lm_residuals = false
    weighted_gap_uo = czm_uo
  []
  [y]
    type = NormalMortarMechanicalContact
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_y
    component = y
    use_displaced_mesh = true
    compute_lm_residuals = false
    weighted_gap_uo = czm_uo
  []
  [c_x]
    type = MortarGenericTraction
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_x
    component = x
    use_displaced_mesh = true
    compute_lm_residuals = false
    cohesive_zone_uo = czm_uo
  []
  [c_y]
    type = MortarGenericTraction
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_y
    component = y
    use_displaced_mesh = true
    compute_lm_residuals = false
    cohesive_zone_uo = czm_uo
  []
[]

[MeshModifiers]
  [pressure_sideset_updater]
    type = MortarCZMDebondedBoundaryUpdater
    block = secondary_lower
    damage_variable = damage
    cohesive_zone_userobject = czm_uo
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    debonded_boundary_primary = czm_pressure_primary
    debonded_boundary_secondary = czm_pressure_secondary
    execute_on = TIMESTEP_END
    # Run before the default group so that the postprocessors see faces promoted this step
    execution_order_group = -1
  []
[]

[Postprocessors]
  # Undisplaced length and first moment of each sideset
  [primary_length]
    type = AreaPostprocessor
    boundary = czm_pressure_primary
  []
  [secondary_length]
    type = AreaPostprocessor
    boundary = czm_pressure_secondary
  []
  [primary_moment]
    type = FunctionSideIntegral
    boundary = czm_pressure_primary
    function = x
  []
  [secondary_moment]
    type = FunctionSideIntegral
    boundary = czm_pressure_secondary
    function = x
  []
  # Area between the two sidesets in the current configuration
  [void_area]
    type = InternalVolume
    boundary = 'czm_pressure_primary czm_pressure_secondary'
    component = 1
  []
  [expected_void_area_separated]
    type = ParsedPostprocessor
    expression = '0.75 * ${opening} * t'
    use_t = true
  []
[]

[Executioner]
  type = Transient
  solve_type = NEWTON
  petsc_options_iname = '-pc_type -pc_factor_mat_solver_type'
  petsc_options_value = 'lu superlu_dist'
  nl_rel_tol = 1e-10
  nl_abs_tol = 1e-10
  # Small enough that each secondary face separates in its own time step (t = 0.45, 0.55, 0.6,
  # 0.7), so that every intermediate state of both sidesets is checked
  dt = 0.05
  end_time = 0.8
[]

[Outputs]
  csv = true
[]

(modules/combined/test/tests/czm_pressure_sidesets/czm_pressure_sideset_cavity.i)

# Pressurization of the sidesets built by MortarCZMDebondedBoundaryUpdater. The
# czm_pressure_sideset.i test is repeated here while the  upper block also
# slides tangentially, so the faces paired in the undisplaced configuration are no
# longer aligned. Once the whole interface has failed the blocks carry no load, so the void between
# the two sidesets must equal the integral of the prescribed opening, opening * t * (1 - x / 2),
# over x in [0, 1], which is 3 / 4 * opening * t.
#
# The void is a cavity, connected to an unmeshed plenum of volume Vp, whose gas pressure follows
# the ideal gas law, p (V + Vp) = n R T, and acts on both sidesets, which is only possible if the
# pressure boundary condition picks up the faces added during the run. Gas is injected at a constant
# rate from full separation at t = 0.8 until t = 1, so the pressure first rises, and then falls as
# the peel keeps enlarging the void. Each block is in uniaxial compression, sigma_yy = -p, so that
#   - the vertical reactions on lower_bottom and upper_top are +p and -p times the interface length;
#   - the lower block displaces by u_y = -p / E * (y + 0.5), and the upper block by
#     p / E * (0.5 - y) in addition to the imposed peel;
#   - the void area is V = V0 + p / E, with V0 = 3 / 4 * opening * t, as each block of height 0.5
#     shortens by p / (2 E).
# These fields are linear, so the elements reproduce them exactly. Substituting V into the gas law
# gives p^2 / E + W p - n R T = 0 with W = V0 + Vp, whose positive root is
#   p = E / 2 * (sqrt(W^2 + 4 n R T / E) - W).

opening = 0.1
slide = 0.02
youngs_modulus = 1e9
gas_constant = 8.314
gas_temperature = 300
# Plenum volume, of the order of the void area, which keeps the gas volume positive while the void
# is still closed
plenum_volume = 0.05
# Injection rate chosen so that the pressure peaks near 1e7 at t = 1; p / E = 0.01 is large enough
# to see in the displacements
gas_rate = 2700

[Mesh]
  # The interface lies on y = 0, so the void integrand -y n_y vanishes on the vertical closing
  # segment at the crack front, which belongs to neither sideset.
  [lower]
    type = GeneratedMeshGenerator
    dim = 2
    xmax = 1
    ymin = -0.5
    ymax = 0
    nx = 4
    ny = 1
    boundary_name_prefix = lower
  []
  [lower_id]
    type = SubdomainIDGenerator
    input = lower
    subdomain_id = 1
  []
  [upper]
    type = GeneratedMeshGenerator
    dim = 2
    xmax = 1
    ymin = 0
    ymax = 0.5
    nx = 3
    ny = 1
    boundary_name_prefix = upper
    boundary_id_offset = 10
  []
  [upper_id]
    type = SubdomainIDGenerator
    input = upper
    subdomain_id = 2
  []
  [combined]
    type = MeshCollectionGenerator
    inputs = 'lower_id upper_id'
  []
  [secondary]
    type = LowerDBlockFromSidesetGenerator
    new_block_id = 10001
    new_block_name = secondary_lower
    sidesets = lower_top
    input = combined
  []
  [primary]
    type = LowerDBlockFromSidesetGenerator
    new_block_id = 10000
    new_block_name = primary_lower
    sidesets = upper_bottom
    input = secondary
  []

  add_sideset_names = 'czm_pressure_primary czm_pressure_secondary'
  add_sideset_ids = '1000 1001'
[]

[GlobalParams]
  displacements = 'disp_x disp_y'
[]

[Problem]
  extra_tag_vectors = 'ref'
[]

[Physics/SolidMechanics/QuasiStatic/all]
  strain = SMALL
  add_variables = true
  use_automatic_differentiation = true
  extra_vector_tags = 'ref'
  block = '1 2'
[]

[AuxVariables]
  [damage]
  []
  [react_y]
    block = '1 2'
  []
[]

[AuxKernels]
  [damage]
    type = CohesiveZoneMortarUserObjectAux
    variable = damage
    user_object = czm_uo
    cohesive_zone_quantity = cohesive_damage
  []
  [react_y]
    type = ReactionForceAux
    vector_tag = 'ref'
    v = disp_y
    variable = react_y
    block = '1 2'
  []
[]

[Functions]
  [gas_moles]
    type = ParsedFunction
    expression = '${gas_rate} * max(min(t, 1) - 0.8, 0)'
  []
  [expected_pressure]
    type = ParsedFunction
    expression = 'W := 0.75 * ${opening} * t + ${plenum_volume};
                  n := ${gas_rate} * max(min(t, 1) - 0.8, 0);
                  ${youngs_modulus} / 2 * (sqrt(W^2 + 4 * n * ${gas_constant} * ${gas_temperature} / ${youngs_modulus}) - W)'
  []
[]

[BCs]
  [fix_x]
    type = DirichletBC
    boundary = lower_bottom
    variable = disp_x
    value = 0
  []
  [fix_y]
    type = DirichletBC
    boundary = lower_bottom
    variable = disp_y
    value = 0
  []
  [slide_x]
    type = FunctionDirichletBC
    boundary = upper_top
    variable = disp_x
    function = '${slide} * t'
  []
  [peel_y]
    type = FunctionDirichletBC
    boundary = upper_top
    variable = disp_y
    function = '${opening} * t * (1 - x / 2)'
  []
  [CavityPressure]
    [void]
      boundary = 'czm_pressure_primary czm_pressure_secondary'
      R = ${gas_constant}
      temperature = gas_temperature
      volume = void_area
      material_input = gas_moles
      additional_volumes = plenum_volume
      temperature_of_additional_volumes = gas_temperature
      output = cavity_pressure
      use_automatic_differentiation = true
      # Act on the undisplaced faces so that the load stays purely normal to the interface and the
      # solution above is exact
      use_displaced_mesh = false
    []
  []
[]

[Materials]
  [elasticity_tensor]
    type = ADComputeIsotropicElasticityTensor
    youngs_modulus = ${youngs_modulus}
    poissons_ratio = 0
    block = '1 2'
  []
  [stress]
    type = ADComputeLinearElasticStress
    block = '1 2'
  []
  [normal_strength]
    type = GenericConstantMaterial
    prop_names = normal_strength
    prop_values = 1e4
  []
  [shear_strength]
    type = GenericConstantMaterial
    prop_names = shear_strength
    prop_values = 1e4
  []
[]

[UserObjects]
  [czm_uo]
    type = BilinearMixedModeCohesiveZoneModel
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    disp_x = disp_x
    disp_y = disp_y
    secondary_variable = disp_x
    use_physical_gap = true
    correct_edge_dropping = true
    normal_strength = normal_strength
    shear_strength = shear_strength
    penalty_stiffness = 1e12
    power_law_parameter = 2
    # Fully separated (damage = 1) once the opening exceeds 2 GI_c / normal_strength = 4e-2, which
    # is much larger than the 1e-5 elastic stretch of the blocks at peak traction, so the response
    # does not snap back
    GI_c = 200
    GII_c = 200
  []
[]

[Constraints]
  [x]
    type = NormalMortarMechanicalContact
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_x
    component = x
    use_displaced_mesh = true
    compute_lm_residuals = false
    weighted_gap_uo = czm_uo
  []
  [y]
    type = NormalMortarMechanicalContact
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_y
    component = y
    use_displaced_mesh = true
    compute_lm_residuals = false
    weighted_gap_uo = czm_uo
  []
  [c_x]
    type = MortarGenericTraction
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_x
    component = x
    use_displaced_mesh = true
    compute_lm_residuals = false
    cohesive_zone_uo = czm_uo
  []
  [c_y]
    type = MortarGenericTraction
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_y
    component = y
    use_displaced_mesh = true
    compute_lm_residuals = false
    cohesive_zone_uo = czm_uo
  []
[]

[MeshModifiers]
  [pressure_sideset_updater]
    type = MortarCZMDebondedBoundaryUpdater
    block = secondary_lower
    damage_variable = damage
    cohesive_zone_userobject = czm_uo
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    debonded_boundary_primary = czm_pressure_primary
    debonded_boundary_secondary = czm_pressure_secondary
    execute_on = TIMESTEP_END
    # Run before the default group so that the postprocessors see faces promoted this step
    execution_order_group = -1
  []
[]

[Postprocessors]
  # Undisplaced length and first moment of each sideset
  [primary_length]
    type = AreaPostprocessor
    boundary = czm_pressure_primary
  []
  [secondary_length]
    type = AreaPostprocessor
    boundary = czm_pressure_secondary
  []
  [primary_moment]
    type = FunctionSideIntegral
    boundary = czm_pressure_primary
    function = x
  []
  [secondary_moment]
    type = FunctionSideIntegral
    boundary = czm_pressure_secondary
    function = x
  []
  # Area between the two sidesets in the current configuration, which is the cavity volume
  [void_area]
    type = InternalVolume
    boundary = 'czm_pressure_primary czm_pressure_secondary'
    component = 1
    execute_on = 'initial linear timestep_end'
  []
  [expected_void_area_separated]
    type = ParsedPostprocessor
    expression = '0.75 * ${opening} * t + expected_pressure / ${youngs_modulus}'
    pp_names = 'expected_pressure'
    use_t = true
  []
  # Cavity inputs
  [gas_moles]
    type = FunctionValuePostprocessor
    function = gas_moles
    execute_on = 'initial linear timestep_end'
  []
  [gas_temperature]
    type = ConstantPostprocessor
    value = ${gas_temperature}
    execute_on = 'initial linear timestep_end'
  []
  [plenum_volume]
    type = ConstantPostprocessor
    value = ${plenum_volume}
    execute_on = 'initial linear timestep_end'
  []
  # Pressure checks, valid after full separation
  [lower_reaction_y]
    type = NodalSum
    variable = react_y
    boundary = lower_bottom
  []
  [upper_reaction_y]
    type = NodalSum
    variable = react_y
    boundary = upper_top
  []
  [expected_pressure]
    type = FunctionValuePostprocessor
    function = expected_pressure
  []
  # The lower block moves only because of the pressure
  [lower_disp_y]
    type = PointValue
    variable = disp_y
    point = '0.5 -0.25 0'
  []
  [expected_lower_disp_y]
    type = ParsedPostprocessor
    expression = '-expected_pressure / ${youngs_modulus} * 0.25'
    pp_names = 'expected_pressure'
  []
[]

[Executioner]
  type = Transient
  solve_type = NEWTON
  petsc_options_iname = '-pc_type -pc_factor_mat_solver_type'
  petsc_options_value = 'lu superlu_dist'
  nl_rel_tol = 1e-10
  nl_abs_tol = 1e-10
  dt = 0.1
  end_time = 1.2
[]

[Outputs]
  csv = true
[]

(modules/combined/test/tests/czm_pressure_sidesets/czm_pressure_sideset.i)

# Two blocks bonded by a mortar cohesive zone are peeled apart from x = 0, so the debonded region
# grows from left to right. Due to the model configuration, each secondary face overlaps one or two
# primary faces.
#
# As each secondary face fully separates, it must be added to czm_pressure_secondary, and every
# primary face it fully overlaps in the undisplaced configuration must be added to
# czm_pressure_primary. The length and first moment (integral of x) of each sideset record which
# faces it holds: a sideset holding the first k faces of width h from x = 0 has length k h and
# first moment (k h)^2 / 2. Once the whole interface has failed the blocks carry no load, so the
# void between the two sidesets must equal the integral of the prescribed opening,
# opening * t * (1 - x / 2), over x in [0, 1], which is 3 / 4 * opening * t.

opening = 0.1

[Mesh]
  # The interface lies on y = 0 and the upper block is not displaced in x, so the void integrand
  # -y n_y vanishes on the vertical closing segments at both ends of the void, which belong to
  # neither sideset.
  [lower]
    type = GeneratedMeshGenerator
    dim = 2
    xmax = 1
    ymin = -0.5
    ymax = 0
    nx = 4
    ny = 1
    boundary_name_prefix = lower
  []
  [lower_id]
    type = SubdomainIDGenerator
    input = lower
    subdomain_id = 1
  []
  [upper]
    type = GeneratedMeshGenerator
    dim = 2
    xmax = 1
    ymin = 0
    ymax = 0.5
    nx = 3
    ny = 1
    boundary_name_prefix = upper
    boundary_id_offset = 10
  []
  [upper_id]
    type = SubdomainIDGenerator
    input = upper
    subdomain_id = 2
  []
  [combined]
    type = MeshCollectionGenerator
    inputs = 'lower_id upper_id'
  []
  [secondary]
    type = LowerDBlockFromSidesetGenerator
    new_block_id = 10001
    new_block_name = secondary_lower
    sidesets = lower_top
    input = combined
  []
  [primary]
    type = LowerDBlockFromSidesetGenerator
    new_block_id = 10000
    new_block_name = primary_lower
    sidesets = upper_bottom
    input = secondary
  []

  add_sideset_names = 'czm_pressure_primary czm_pressure_secondary'
  add_sideset_ids = '1000 1001'
[]

[GlobalParams]
  displacements = 'disp_x disp_y'
[]

[Physics/SolidMechanics/QuasiStatic/all]
  strain = SMALL
  add_variables = true
  use_automatic_differentiation = true
  block = '1 2'
[]

[AuxVariables]
  [damage]
  []
[]

[AuxKernels]
  [damage]
    type = CohesiveZoneMortarUserObjectAux
    variable = damage
    user_object = czm_uo
    cohesive_zone_quantity = cohesive_damage
  []
[]

[BCs]
  [fix_x]
    type = DirichletBC
    boundary = lower_bottom
    variable = disp_x
    value = 0
  []
  [fix_y]
    type = DirichletBC
    boundary = lower_bottom
    variable = disp_y
    value = 0
  []
  [fix_upper_x]
    type = DirichletBC
    boundary = upper_top
    variable = disp_x
    value = 0
  []
  [peel_y]
    type = FunctionDirichletBC
    boundary = upper_top
    variable = disp_y
    function = '${opening} * t * (1 - x / 2)'
  []
[]

[Materials]
  [elasticity_tensor]
    type = ADComputeIsotropicElasticityTensor
    youngs_modulus = 1e9
    poissons_ratio = 0
    block = '1 2'
  []
  [stress]
    type = ADComputeLinearElasticStress
    block = '1 2'
  []
  [normal_strength]
    type = GenericConstantMaterial
    prop_names = normal_strength
    prop_values = 1e4
  []
  [shear_strength]
    type = GenericConstantMaterial
    prop_names = shear_strength
    prop_values = 1e4
  []
[]

[UserObjects]
  [czm_uo]
    type = BilinearMixedModeCohesiveZoneModel
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    disp_x = disp_x
    disp_y = disp_y
    secondary_variable = disp_x
    use_physical_gap = true
    correct_edge_dropping = true
    normal_strength = normal_strength
    shear_strength = shear_strength
    penalty_stiffness = 1e12
    power_law_parameter = 2
    # Fully separated (damage = 1) once the opening exceeds 2 GI_c / normal_strength = 4e-2, which
    # is much larger than the 1e-5 elastic stretch of the blocks at peak traction, so the response
    # does not snap back
    GI_c = 200
    GII_c = 200
  []
[]

[Constraints]
  [x]
    type = NormalMortarMechanicalContact
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_x
    component = x
    use_displaced_mesh = true
    compute_lm_residuals = false
    weighted_gap_uo = czm_uo
  []
  [y]
    type = NormalMortarMechanicalContact
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_y
    component = y
    use_displaced_mesh = true
    compute_lm_residuals = false
    weighted_gap_uo = czm_uo
  []
  [c_x]
    type = MortarGenericTraction
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_x
    component = x
    use_displaced_mesh = true
    compute_lm_residuals = false
    cohesive_zone_uo = czm_uo
  []
  [c_y]
    type = MortarGenericTraction
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    secondary_variable = disp_y
    component = y
    use_displaced_mesh = true
    compute_lm_residuals = false
    cohesive_zone_uo = czm_uo
  []
[]

[MeshModifiers]
  [pressure_sideset_updater]
    type = MortarCZMDebondedBoundaryUpdater
    block = secondary_lower
    damage_variable = damage
    cohesive_zone_userobject = czm_uo
    primary_boundary = upper_bottom
    secondary_boundary = lower_top
    primary_subdomain = primary_lower
    secondary_subdomain = secondary_lower
    debonded_boundary_primary = czm_pressure_primary
    debonded_boundary_secondary = czm_pressure_secondary
    execute_on = TIMESTEP_END
    # Run before the default group so that the postprocessors see faces promoted this step
    execution_order_group = -1
  []
[]

[Postprocessors]
  # Undisplaced length and first moment of each sideset
  [primary_length]
    type = AreaPostprocessor
    boundary = czm_pressure_primary
  []
  [secondary_length]
    type = AreaPostprocessor
    boundary = czm_pressure_secondary
  []
  [primary_moment]
    type = FunctionSideIntegral
    boundary = czm_pressure_primary
    function = x
  []
  [secondary_moment]
    type = FunctionSideIntegral
    boundary = czm_pressure_secondary
    function = x
  []
  # Area between the two sidesets in the current configuration
  [void_area]
    type = InternalVolume
    boundary = 'czm_pressure_primary czm_pressure_secondary'
    component = 1
  []
  [expected_void_area_separated]
    type = ParsedPostprocessor
    expression = '0.75 * ${opening} * t'
    use_t = true
  []
[]

[Executioner]
  type = Transient
  solve_type = NEWTON
  petsc_options_iname = '-pc_type -pc_factor_mat_solver_type'
  petsc_options_value = 'lu superlu_dist'
  nl_rel_tol = 1e-10
  nl_abs_tol = 1e-10
  # Small enough that each secondary face separates in its own time step (t = 0.45, 0.55, 0.6,
  # 0.7), so that every intermediate state of both sidesets is checked
  dt = 0.05
  end_time = 0.8
[]

[Outputs]
  csv = true
[]

Description
Example Input Syntax
Input Parameters
Input Files