Critical Time Step Postprocessor

Computes and reports the critical time step for the explicit solver.

Description

The CriticalTimeStep postprocessor is used to compute the value of the minimum time step for explicit integration scheme. Please refer to CriticalTimeStepMath for the theoretical details.

Input Parameters

blockThe list of block ids (SubdomainID) that this object will be applied
C++ Type:std::vector
Options:
Description:The list of block ids (SubdomainID) that this object will be applied
densityName of Material Property or a constant real number defining the density of the material.
C++ Type:MaterialPropertyName
Options:
Description:Name of Material Property or a constant real number defining the density of the material.
execute_onTIMESTEP_ENDThe list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM.
Default:TIMESTEP_END
C++ Type:ExecFlagEnum
Options:NONE INITIAL LINEAR NONLINEAR TIMESTEP_END TIMESTEP_BEGIN FINAL CUSTOM TRANSFER
Description:The list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM.
factor1Factor to mulitply to the critical time step.
Default:1
C++ Type:double
Options:
Description:Factor to mulitply to the critical time step.

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
Options:
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
Options:
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Options:
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
Options:
Description:Determines whether this object is calculated using an implicit or explicit form
outputsVector of output names were you would like to restrict the output of variables(s) associated with this object
C++ Type:std::vector
Options:
Description:Vector of output names were you would like to restrict the output of variables(s) associated with this object
seed0The seed for the master random number generator
Default:0
C++ Type:unsigned int
Options:
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
Options:
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

Input Files

modules/tensor_mechanics/test/tests/critical_time_step/timoshenko_smallstrain_critstep.i
modules/tensor_mechanics/test/tests/critical_time_step/crit_time_solid_variable.i
modules/tensor_mechanics/test/tests/critical_time_step/crit_time_solid_uniform.i
modules/tensor_mechanics/test/tests/critical_time_step/non-isotropic_error_test.i

modules/tensor_mechanics/test/tests/critical_time_step/timoshenko_smallstrain_critstep.i

# Test for small strain timoshenko beam bending in y direction

# A unit load is applied at the end of a cantilever beam of length 4m.
# The properties of the cantilever beam are as follows:
# Young's modulus (E) = 2.60072400269
# Shear modulus (G) = 1.00027846257
# Poisson's ratio (nu) = 0.3
# Shear coefficient (k) = 0.85
# Cross-section area (A) = 0.554256
# Iy = 0.0141889 = Iz
# Length = 4 m

# For this beam, the dimensionless parameter alpha = kAGL^2/EI = 204.3734

# The small deformation analytical deflection of the beam is given by
# delta = PL^3/3EI * (1 + 3.0 / alpha) = 5.868e-4 m

# Using 10 elements to discretize the beam element, the FEM solution is 5.852e-2m.
# This deflection matches the FEM solution given in Prathap and Bhashyam (1982).

# References:
# Prathap and Bhashyam (1982), International journal for numerical methods in engineering, vol. 18, 195-210.
# Note that the force is scaled by 1e-4 compared to the reference problem.

[Mesh]
  type = GeneratedMesh
  dim = 1
  nx = 10
  xmin = 0.0
  xmax = 4.0
  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
  [../]
  [./rot_x]
    order = FIRST
    family = LAGRANGE
  [../]
  [./rot_y]
    order = FIRST
    family = LAGRANGE
  [../]
  [./rot_z]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[BCs]
  [./fixx1]
    type = DirichletBC
    variable = disp_x
    boundary = left
    value = 0.0
  [../]
  [./fixy1]
    type = DirichletBC
    variable = disp_y
    boundary = left
    value = 0.0
  [../]
  [./fixz1]
    type = DirichletBC
    variable = disp_z
    boundary = left
    value = 0.0
  [../]
  [./fixr1]
    type = DirichletBC
    variable = rot_x
    boundary = left
    value = 0.0
  [../]
  [./fixr2]
    type = DirichletBC
    variable = rot_y
    boundary = left
    value = 0.0
  [../]
  [./fixr3]
    type = DirichletBC
    variable = rot_z
    boundary = left
    value = 0.0
  [../]
[]

[NodalKernels]
  [./force_y2]
    type = ConstantRate
    variable = disp_y
    boundary = right
    rate = 1.0e-4
  [../]
[]

[Preconditioning]
  [./smp]
    type = SMP
    full = true
  [../]
[]
[Executioner]
  type = Transient
  solve_type = NEWTON
  line_search = 'none'
  nl_max_its = 15
  nl_rel_tol = 1e-10
  nl_abs_tol = 1e-10

  dt = 1
  dtmin = 1
  end_time = 1
[]

[Kernels]
  [./solid_disp_x]
    type = StressDivergenceBeam
    block = '0'
    displacements = 'disp_x disp_y disp_z'
    rotations = 'rot_x rot_y rot_z'
    component = 0
    variable = disp_x
  [../]
  [./solid_disp_y]
    type = StressDivergenceBeam
    block = '0'
    displacements = 'disp_x disp_y disp_z'
    rotations = 'rot_x rot_y rot_z'
    component = 1
    variable = disp_y
  [../]
  [./solid_disp_z]
    type = StressDivergenceBeam
    block = '0'
    displacements = 'disp_x disp_y disp_z'
    rotations = 'rot_x rot_y rot_z'
    component = 2
    variable = disp_z
  [../]
  [./solid_rot_x]
    type = StressDivergenceBeam
    block = '0'
    displacements = 'disp_x disp_y disp_z'
    rotations = 'rot_x rot_y rot_z'
    component = 3
    variable = rot_x
  [../]
  [./solid_rot_y]
    type = StressDivergenceBeam
    block = '0'
    displacements = 'disp_x disp_y disp_z'
    rotations = 'rot_x rot_y rot_z'
    component = 4
    variable = rot_y
  [../]
  [./solid_rot_z]
    type = StressDivergenceBeam
    block = '0'
    displacements = 'disp_x disp_y disp_z'
    rotations = 'rot_x rot_y rot_z'
    component = 5
    variable = rot_z
  [../]
[]

[Materials]
  [./elasticity]
    type = ComputeElasticityBeam
    youngs_modulus = 2.60072400269
    poissons_ratio = 0.3
    shear_coefficient = 0.85
    block = 0
  [../]
  [./strain]
    type = ComputeIncrementalBeamStrain
    block = '0'
    displacements = 'disp_x disp_y disp_z'
    rotations = 'rot_x rot_y rot_z'
    area = 0.554256
    Ay = 0.0
    Az = 0.0
    Iy = 0.0141889
    Iz = 0.0141889
    y_orientation = '0.0 1.0 0.0'
  [../]
  [./stress]
    type = ComputeBeamResultants
    block = 0
  [../]
  [./density]
    type = GenericConstantMaterial
    prop_names = 'density'
    prop_values = '8050.0'
  [../]
[]

[Postprocessors]
  [./disp_x]
    type = PointValue
    point = '4.0 0.0 0.0'
    variable = disp_x
  [../]
  [./disp_y]
    type = PointValue
    point = '4.0 0.0 0.0'
    variable = disp_y
  [../]
  [./time_step]
    type = CriticalTimeStep
  [../]
[]

[Outputs]
  exodus = true
  csv = true
[]

modules/tensor_mechanics/test/tests/critical_time_step/crit_time_solid_variable.i

[GlobalParams]
  displacements = 'disp_x'
[]

[Mesh]
  type = GeneratedMesh
  dim = 1
  nx = 50

  xmin = 0
  xmax = 5
[]

[Variables]
  [./disp_x]
  [../]
[]

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

[BCs]
  [./2_x]
    type = DirichletBC
    variable = disp_x
    boundary = 1
    value = 0.0
  [../]
[]

[Functions]
  [./prefac]
    type = ParsedFunction
    value = '1+2*x'
  [../]
[]

[Materials]
  [./elasticity_tensor]
    type = ComputeIsotropicElasticityTensor
    poissons_ratio = 0.1
    youngs_modulus = 1e6
    elasticity_tensor_prefactor = prefac
  [../]
  [./strain]
    type = ComputeSmallStrain
  [../]
  [./stress]
    type = ComputeLinearElasticStress
  [../]
  [./density]
    type = GenericConstantMaterial
    prop_names = 'density'
    prop_values = '8050.0'
  [../]
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK'

  nl_abs_tol = 1e-4

  l_max_its = 3

  start_time = 0.0
  dt = 0.1
  num_steps = 1
  end_time = 1.0
[]

[Postprocessors]
  [./time_step]
    type = CriticalTimeStep
  [../]
[]

[Outputs]
  exodus = true
  csv = true
[]

modules/tensor_mechanics/test/tests/critical_time_step/crit_time_solid_uniform.i

[GlobalParams]
  displacements = 'disp_x disp_y disp_z'
[]

[Mesh]
  type = GeneratedMesh
  dim = 3
  nx = 10
  ny = 10
  nz = 15

  xmin = 0
  xmax = 2

  ymin = 0
  ymax = 2

  zmin = 0
  zmax = 1
[]

[Variables]
  [./disp_x]
  [../]
  [./disp_y]
  [../]
  [./disp_z]
  [../]
[]

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

[BCs]
  [./2_x]
    type = DirichletBC
    variable = disp_x
    boundary = 3
    value = 0.0
  [../]
  [./2_y]
    type = DirichletBC
    variable = disp_y
    boundary = 3
    value = 0.0
  [../]
  [./2_z]
    type = DirichletBC
    variable = disp_z
    boundary = 3
    value = 0.0
  [../]
[]

[Materials]
  [./elasticity_tensor]
    type = ComputeIsotropicElasticityTensor
    poissons_ratio = 0.1
    youngs_modulus = 1e6
  [../]
  [./strain]
    type = ComputeSmallStrain
  [../]
  [./stress]
    type = ComputeLinearElasticStress
  [../]
  [./density]
    type = GenericConstantMaterial
    prop_names = 'density'
    prop_values = '8050.0'
  [../]
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK'

  nl_abs_tol = 1e-4

  l_max_its = 3

  start_time = 0.0
  dt = 0.1
  num_steps = 1
  end_time = 1.0
[]

[Postprocessors]
  [./time_step]
    type = CriticalTimeStep
  [../]
[]

[Outputs]
  exodus = true
  csv = true
[]

modules/tensor_mechanics/test/tests/critical_time_step/non-isotropic_error_test.i

[GlobalParams]
  displacements = 'disp_x disp_y disp_z'
[]

[Mesh]
  type = GeneratedMesh
  dim = 3
  nx = 10
  ny = 10
  nz = 15

  xmin = 0
  xmax = 2

  ymin = 0
  ymax = 2

  zmin = 0
  zmax = 1
[]

[Variables]
  [./disp_x]
  [../]
  [./disp_y]
  [../]
  [./disp_z]
  [../]
[]

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

[BCs]
  [./2_x]
    type = DirichletBC
    variable = disp_x
    boundary = 3
    value = 0.0
  [../]
  [./2_y]
    type = DirichletBC
    variable = disp_y
    boundary = 3
    value = 0.0
  [../]
  [./2_z]
    type = DirichletBC
    variable = disp_z
    boundary = 3
    value = 0.0
  [../]
[]

[Materials]
  [./elasticity_tensor]
    type = ComputeElasticityTensor
  C_ijkl = '1.684e5 0.176e5 0.176e5 1.684e5 0.176e5 1.684e5 0.754e5 0.754e5 0.754e5'
  fill_method = symmetric9
  [../]
  [./strain]
    type = ComputeSmallStrain
  [../]
  [./stress]
    type = ComputeLinearElasticStress
  [../]
  [./density]
    type = GenericConstantMaterial
    prop_names = 'density'
    prop_values = '8050.0'
  [../]
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK'

  nl_abs_tol = 1e-4

  l_max_its = 3

  start_time = 0.0
  dt = 0.1
  num_steps = 1
  end_time = 1.0
[]

[Postprocessors]
  [./time_step]
    type = CriticalTimeStep
  [../]
[]

[Outputs]
  file_base = out
  exodus = true
  csv = true
[]

Description
Input Parameters
Input Files

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