Linear Viscoelasticity Manager

Manages the updating of the semi-implicit single-step first-order finite difference time-stepping scheme

Description

This updates the internal time-stepping scheme for linear viscoelastic materials (such as a GeneralizedKelvinVoigtModel or a GeneralizedMaxwellModel material) at the beginning of each time step. Including a LinearViscoelasticStressUpdate in the simulation is required for the linear viscoelastic strains to be updated properly.

Example Input File Syntax

[./update]
  type = LinearViscoelasticityManager
  viscoelastic_model = kelvin_voigt
[../]

Input Parameters

viscoelastic_modelname of the LinearViscoelasticityBase object to manage
C++ Type:std::string
Controllable:No
Description:name of the LinearViscoelasticityBase object to manage

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
creep_strain_namecreep_strainname of the creep strain tensor used for the viscoelastic update
Default:creep_strain
C++ Type:std::string
Controllable:No
Description:name of the creep strain tensor used for the viscoelastic update
elastic_strain_nameelastic_strainname of the elastic strain tensor used for the viscoelastic update
Default:elastic_strain
C++ Type:std::string
Controllable:No
Description:name of the elastic strain tensor used for the viscoelastic update
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
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.
stress_namestressname of the stress tensor used for the viscoelastic update
Default:stress
C++ Type:std::string
Controllable:No
Description:name of the stress tensor used for the viscoelastic update

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).
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.
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
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

(moose/modules/tensor_mechanics/test/tests/visco/visco_finite_strain.i)

[Mesh]
  type = GeneratedMesh
  dim = 3
  nx = 1
  ny = 1
  nz = 1
  elem_type = HEX8
  displacements = 'disp_x disp_y disp_z'
[]

[Variables]
  [./disp_x]
    order = FIRST
    family = LAGRANGE
  [../]
  [./disp_y]
    order = FIRST
    family = LAGRANGE
  [../]
  [./disp_z]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[AuxVariables]
  [./stress_xx]
    order = CONSTANT
    family = MONOMIAL
  [../]
  [./strain_xx]
    order = CONSTANT
    family = MONOMIAL
  [../]
  [./creep_strain_xx]
    order = CONSTANT
    family = MONOMIAL
  [../]
[]

[Kernels]
  [./TensorMechanics]
    displacements = 'disp_x disp_y disp_z'
    use_displaced_mesh = true
  [../]
[]

[AuxKernels]
  [./stress_xx]
    type = RankTwoAux
    variable = stress_xx
    rank_two_tensor = stress
    index_j = 0
    index_i = 0
    execute_on = timestep_end
  [../]
  [./strain_xx]
    type = RankTwoAux
    variable = strain_xx
    rank_two_tensor = total_strain
    index_j = 0
    index_i = 0
    execute_on = timestep_end
  [../]
  [./creep_strain_xx]
    type = RankTwoAux
    variable = creep_strain_xx
    rank_two_tensor = creep_strain
    index_j = 0
    index_i = 0
    execute_on = timestep_end
  [../]
[]

[BCs]
  [./symmy]
    type = DirichletBC
    variable = disp_y
    boundary = bottom
    value = 0
  [../]
  [./symmx]
    type = DirichletBC
    variable = disp_x
    boundary = left
    value = 0
  [../]
  [./symmz]
    type = DirichletBC
    variable = disp_z
    boundary = back
    value = 0
  [../]
  [./axial_load]
    type = NeumannBC
    variable = disp_x
    boundary = right
    value    = 10e6
  [../]
[]

[Materials]
  [./kelvin_voigt]
    type = GeneralizedKelvinVoigtModel
    creep_modulus = '10e9 10e9'
    creep_viscosity = '1 10'
    poisson_ratio = 0.2
    young_modulus = 10e9
  [../]
  [./stress]
    type = ComputeMultipleInelasticStress
    inelastic_models = 'creep'
  [../]
  [./creep]
    type = LinearViscoelasticStressUpdate
  [../]
  [./strain]
    type = ComputeFiniteStrain
    displacements = 'disp_x disp_y disp_z'
  [../]
[]

[UserObjects]
  [./update]
    type = LinearViscoelasticityManager
    viscoelastic_model = kelvin_voigt
  [../]
[]

[Postprocessors]
  [./stress_xx]
    type = ElementAverageValue
    variable = stress_xx
    block = 'ANY_BLOCK_ID 0'
  [../]
  [./strain_xx]
    type = ElementAverageValue
    variable = strain_xx
    block = 'ANY_BLOCK_ID 0'
  [../]
  [./creep_strain_xx]
    type = ElementAverageValue
    variable = creep_strain_xx
    block = 'ANY_BLOCK_ID 0'
  [../]
[]

[Preconditioning]
  [./smp]
    type = SMP
    full = true
  [../]
[]

[Executioner]
  type = Transient

  l_max_its  = 100
  l_tol      = 1e-8
  nl_max_its = 50
  nl_rel_tol = 1e-8
  nl_abs_tol = 1e-8

  dtmin = 0.01
  end_time = 100
  [./TimeStepper]
    type = LogConstantDT
    first_dt = 0.1
    log_dt = 0.1
  [../]

[]

[Outputs]
  file_base = visco_finite_strain_out
  exodus = true
[]