GlobalStrain

Scalar Kernel to solve for the global strain

Description

GlobalStrain solves the ODE equation setting the integral of the stress generated by applied load or volume change unrelated to deformation to zero. It stores the strain components into scalar variables of different order. Strain components calculated from this scalar kernel contributes towards the periodic strain. Combined with periodic displacements, this helps maintaining full strain periodicity.

It requires an input of the UserObject that calculates the integral value and corresponding jacobians.

Please refer to GlobalStrainUserObject for information about the residual and jacobian calculation.

Example Input File Syntax

[./global_strain]
  type = GlobalStrain
  variable = global_strain
  global_strain_uo = global_strain_uo
[../]

Input Parameters

global_strain_uoThe name of the GlobalStrainUserObject
C++ Type:UserObjectName
Controllable:No
Description:The name of the GlobalStrainUserObject
variableThe name of the variable that this residual object operates on
C++ Type:NonlinearVariableName
Controllable:No
Description:The name of the variable that this residual object operates on

Required Parameters

absolute_value_vector_tagsThe tags for the vectors this residual object should fill with the absolute value of the residual contribution
C++ Type:std::vector<TagName>
Controllable:No
Description:The tags for the vectors this residual object should fill with the absolute value of the residual contribution
extra_matrix_tagsThe extra tags for the matrices this Kernel should fill
C++ Type:std::vector<TagName>
Controllable:No
Description:The extra tags for the matrices this Kernel should fill
extra_vector_tagsThe extra tags for the vectors this Kernel should fill
C++ Type:std::vector<TagName>
Controllable:No
Description:The extra tags for the vectors this Kernel should fill
matrix_tagssystemThe tag for the matrices this Kernel should fill
Default:system
C++ Type:MultiMooseEnum
Options:nontime, system
Controllable:No
Description:The tag for the matrices this Kernel should fill
vector_tagsnontimeThe tag for the vectors this Kernel should fill
Default:nontime
C++ Type:MultiMooseEnum
Options:nontime, time
Controllable:No
Description:The tag for the vectors this Kernel should fill

Tagging 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

(../moose/modules/tensor_mechanics/test/tests/global_strain/global_strain.i)

[Mesh]
  [generated_mesh]
    type = GeneratedMeshGenerator
    dim = 2
    nx = 10
    ny = 10
    xmin = -0.5
    xmax = 0.5
    ymin = -0.5
    ymax = 0.5
  []
  [cnode]
    type = ExtraNodesetGenerator
    coord = '0 0'
    new_boundary = 100
    input = generated_mesh
  []
[]

[Variables]
  [./u_x]
  [../]
  [./u_y]
  [../]
  [./global_strain]
    order = THIRD
    family = SCALAR
  [../]
[]

[AuxVariables]
  [./disp_x]
  [../]
  [./disp_y]
  [../]
[]

[AuxKernels]
  [./disp_x]
    type = GlobalDisplacementAux
    variable = disp_x
    scalar_global_strain = global_strain
    global_strain_uo = global_strain_uo
    component = 0
  [../]
  [./disp_y]
    type = GlobalDisplacementAux
    variable = disp_y
    scalar_global_strain = global_strain
    global_strain_uo = global_strain_uo
    component = 1
  [../]
[]

[GlobalParams]
  displacements = 'u_x u_y'
  block = 0
[]

[Kernels]
  [./TensorMechanics]
  [../]
[]

[ScalarKernels]
  [./global_strain]
    type = GlobalStrain
    variable = global_strain
    global_strain_uo = global_strain_uo
  [../]
[]

[BCs]
  [./Periodic]
    [./left-right]
      auto_direction = 'x y'
      variable = 'u_x u_y'
    [../]
  [../]

  # fix center point location
  [./centerfix_x]
    type = DirichletBC
    boundary = 100
    variable = u_x
    value = 0
  [../]
  [./centerfix_y]
    type = DirichletBC
    boundary = 100
    variable = u_y
    value = 0
  [../]
[]

[Materials]
  [./elasticity_tensor]
    type = ComputeElasticityTensor
    block = 0
    C_ijkl = '1 1'
    fill_method = symmetric_isotropic
  [../]
  [./strain]
    type = ComputeSmallStrain
    global_strain = global_strain
  [../]
  [./global_strain]
    type = ComputeGlobalStrain
    scalar_global_strain = global_strain
    global_strain_uo = global_strain_uo
  [../]
  [./stress]
    type = ComputeLinearElasticStress
  [../]
[]

[UserObjects]
  [./global_strain_uo]
    type = GlobalStrainUserObject
    applied_stress_tensor = '0.1 0.2 0 0 0 -0.2'
    execute_on = 'Initial Linear Nonlinear'
  [../]
[]

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

[Executioner]
  type = Transient
  scheme = bdf2
  solve_type = 'PJFNK'

  line_search = basic

  petsc_options_iname = '-pc_type -ksp_gmres_restart -sub_ksp_type -sub_pc_type -pc_asm_overlap'
  petsc_options_value = 'asm         31   preonly   lu      1'

  l_max_its = 30
  nl_max_its = 12

  l_tol = 1.0e-4

  nl_rel_tol = 1.0e-8
  nl_abs_tol = 1.0e-10

  start_time = 0.0
  num_steps = 2
[]

[Outputs]
exodus = true
[]