ComputeVonMisesStress

Compute vonMises stress.

ComputeVonMisesStress computes the scalar von Mises equivalent stress from a rank-2 stress tensor field. Formulas for 2D and 3D are supported.

Overview

Given Cauchy "stress" components $var element = document.getElementById("moose-equation-aa19cbaa-2d2c-440d-ab63-1f76aeecd0dc");katex.render("\\sigma_{ij}", element, {displayMode:false,throwOnError:false});$ , the 3D equivalent stress is

$var element = document.getElementById("moose-equation-77410700-50cb-401e-9860-fea23af17b90");katex.render("\\sigma_v = \\sqrt{\\tfrac{1}{2} \\big[(\\sigma_{xx}-\\sigma_{yy})^2 + (\\sigma_{yy}-\\sigma_{zz})^2 + (\\sigma_{zz}-\\sigma_{xx})^2 + 6(\\sigma_{xy}^2+\\sigma_{yz}^2+\\sigma_{zx}^2)\\big]}.", element, {displayMode:true,throwOnError:false});$

For 2D, the expression reduces accordingly.

Example Input File Syntax

[TensorComputes<<<{"href": "../../syntax/TensorComputes/index.html"}>>>]
  [Postprocess<<<{"href": "../../syntax/TensorComputes/Postprocess/index.html"}>>>]
    [vonmises]
      type = ComputeVonMisesStress<<<{"description": "Compute vonMises stress.", "href": "ComputeVonMisesStress.html"}>>>
      buffer<<<{"description": "The buffer this compute is writing to"}>>> = sV
    []
  []
[]

Input Parameters

bufferThe buffer this compute is writing to
C++ Type:std::string
Controllable:No
Description:The buffer this compute is writing to

Required Parameters

stressstressStress tensor.
Default:stress
C++ Type:std::string
Controllable:No
Description:Stress tensor.

Optional 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:No
Description:Set the enabled status of the MooseObject.

Advanced Parameters

(test/tests/mechanics/mech.i)

[Domain]
  dim = 2
  nx = 32
  ny = 32
  xmax = ${fparse 2*pi}
  ymax = ${fparse 2*pi}
  zmax = ${fparse 2*pi}
  mesh_mode = DUMMY
  parallel_mode = FFT_AUTO
[]

[TensorComputes]
  [Initialize]
    [phase]
      type = ParsedCompute
      expression = '(cos(x)/2+0.5)^1*(cos(y)/2+0.5)^1*(cos(z)/2+0.5)^1'
      extra_symbols = true
      buffer = phase
    []
    [K]
      type = ParsedCompute
      buffer = K
      expression = '(1-phase)*Ka + phase*Kb'
      inputs = phase
      constant_names = 'Ka Kb'
      constant_expressions = '1 10'
    []
    [mu]
      type = ParsedCompute
      buffer = mu
      expression = '(1-phase)*mua + phase*mub'
      inputs = phase
      constant_names = 'mua mub'
      constant_expressions = '0.5 5'
    []
    [Finit]
      type = RankTwoIdentity
      buffer = F
    []
  []

  [Solve]
    [hyper_elasticity]
      type = HyperElasticIsotropic
      buffer = stress
      F = Fnew
      K = K
      mu = mu
    []

    [root]
      [applied_strain]
        type = MacroscopicShearTensor
        buffer = applied_strain
      []
      [mech]
        type = FFTMechanics
        buffer = Fnew
        F = F
        K = K
        mu = mu
        l_max_its = 40
        l_tol = 1e-5
        nl_rel_tol = 2e-4
        nl_abs_tol = 2e-3
        constitutive_model = hyper_elasticity
        stress = stress
        applied_macroscopic_strain = applied_strain
      []
    []
  []

  [Postprocess]
    [displacements]
      type = ComputeDisplacements
      buffer = disp
      F = F
    []
    [vonmises]
      type = ComputeVonMisesStress
      buffer = sV
    []
  []
[]

[TensorSolver]
  # no variables are integrated by this solver (FFTMechanics performs a steady state mechanics solve)
  type = ForwardEulerSolver
  root_compute = root
  # deformation tensor is just forwarded Fnew -> F
  forward_buffer = F
  forward_buffer_new = Fnew
  substeps = 3
[]

[TensorOutputs]
  active = 'parallel' # serial

  [serial]
    type = XDMFTensorOutput
    file_base = mech_serial
    buffer = 'disp sV F phase'
    output_mode = 'OVERSIZED_NODAL CELL CELL NODE'
    enable_hdf5 = true
    execute_on = 'TIMESTEP_END'
  []
  [parallel]
    # NODE and OVERSIZED_NODAL are not yet available in parallel output
    type = XDMFTensorOutput
    file_base = mech_parallel
    buffer = 'sV F phase'
    output_mode = 'CELL CELL CELL'
    enable_hdf5 = true
    execute_on = 'TIMESTEP_END'
  []
[]


[Executioner]
  type = Transient
  num_steps = 3
  dt = 0.02
[]

(examples/degeus_mechanics/mech.i)

[Domain]
  dim = 3
  nx = 32
  ny = 32
  nz = 32
  xmax = ${fparse 2*pi}
  ymax = ${fparse 2*pi}
  zmax = ${fparse 2*pi}
  mesh_mode = DUMMY
[]

[TensorComputes]
  [Initialize]
    [Finit]
      type = RankTwoIdentity
      buffer = F
    []

    [phase]
      type = PhaseMechanicsTest
      buffer = phase
    []
    [K]
      type = ParsedCompute
      buffer = K
      expression = '(1-phase)*Ka + phase*Kb'
      inputs = phase
      constant_names = 'Ka Kb'
      constant_expressions = '0.833 8.33'
    []
    [mu]
      type = ParsedCompute
      buffer = mu
      expression = '(1-phase)*mua + phase*mub'
      inputs = phase
      constant_names = 'mua mub'
      constant_expressions = '0.386 3.86'
    []
  []

  [Solve]
    [hyper_elasticity]
      type = HyperElasticIsotropic
      buffer = stress
      F = Fnew
      K = K
      mu = mu
    []

    [root]
      [applied_strain]
        type = MacroscopicShearTensor
        buffer = applied_strain
      []
      [mech]
        type = FFTMechanics
        buffer = Fnew
        F = F
        K = K
        mu = mu
        l_tol = 1e-2
        nl_rel_tol = 2e-2
        nl_abs_tol = 2e-2
        constitutive_model = hyper_elasticity
        stress = stress
        applied_macroscopic_strain = applied_strain
      []
    []
  []

  [Postprocess]
    [displacements]
      type = ComputeDisplacements
      buffer = disp
      F = F
    []
    [vonmises]
      type = ComputeVonMisesStress
      buffer = sV
    []
  []
[]

[TensorSolver]
  # no variables are integrated by this solver (FFTMechanics performs a steady state mechanics solve)
  type = ForwardEulerSolver
  root_compute = root
  # deformation tensor is just forwarded Fnew -> F
  forward_buffer = F
  forward_buffer_new = Fnew
  substeps = 10
[]

[TensorOutputs]
  [deformation_tensor]
    type = XDMFTensorOutput
    buffer = 'disp sV F'
    output_mode = 'OVERSIZED_NODAL CELL CELL'
    enable_hdf5 = true
  []
[]

[Executioner]
  type = Transient
  num_steps = 100
  dt = 0.01
[]

(test/tests/mechanics/mech.i)

[Domain]
  dim = 2
  nx = 32
  ny = 32
  xmax = ${fparse 2*pi}
  ymax = ${fparse 2*pi}
  zmax = ${fparse 2*pi}
  mesh_mode = DUMMY
  parallel_mode = FFT_AUTO
[]

[TensorComputes]
  [Initialize]
    [phase]
      type = ParsedCompute
      expression = '(cos(x)/2+0.5)^1*(cos(y)/2+0.5)^1*(cos(z)/2+0.5)^1'
      extra_symbols = true
      buffer = phase
    []
    [K]
      type = ParsedCompute
      buffer = K
      expression = '(1-phase)*Ka + phase*Kb'
      inputs = phase
      constant_names = 'Ka Kb'
      constant_expressions = '1 10'
    []
    [mu]
      type = ParsedCompute
      buffer = mu
      expression = '(1-phase)*mua + phase*mub'
      inputs = phase
      constant_names = 'mua mub'
      constant_expressions = '0.5 5'
    []
    [Finit]
      type = RankTwoIdentity
      buffer = F
    []
  []

  [Solve]
    [hyper_elasticity]
      type = HyperElasticIsotropic
      buffer = stress
      F = Fnew
      K = K
      mu = mu
    []

    [root]
      [applied_strain]
        type = MacroscopicShearTensor
        buffer = applied_strain
      []
      [mech]
        type = FFTMechanics
        buffer = Fnew
        F = F
        K = K
        mu = mu
        l_max_its = 40
        l_tol = 1e-5
        nl_rel_tol = 2e-4
        nl_abs_tol = 2e-3
        constitutive_model = hyper_elasticity
        stress = stress
        applied_macroscopic_strain = applied_strain
      []
    []
  []

  [Postprocess]
    [displacements]
      type = ComputeDisplacements
      buffer = disp
      F = F
    []
    [vonmises]
      type = ComputeVonMisesStress
      buffer = sV
    []
  []
[]

[TensorSolver]
  # no variables are integrated by this solver (FFTMechanics performs a steady state mechanics solve)
  type = ForwardEulerSolver
  root_compute = root
  # deformation tensor is just forwarded Fnew -> F
  forward_buffer = F
  forward_buffer_new = Fnew
  substeps = 3
[]

[TensorOutputs]
  active = 'parallel' # serial

  [serial]
    type = XDMFTensorOutput
    file_base = mech_serial
    buffer = 'disp sV F phase'
    output_mode = 'OVERSIZED_NODAL CELL CELL NODE'
    enable_hdf5 = true
    execute_on = 'TIMESTEP_END'
  []
  [parallel]
    # NODE and OVERSIZED_NODAL are not yet available in parallel output
    type = XDMFTensorOutput
    file_base = mech_parallel
    buffer = 'sV F phase'
    output_mode = 'CELL CELL CELL'
    enable_hdf5 = true
    execute_on = 'TIMESTEP_END'
  []
[]


[Executioner]
  type = Transient
  num_steps = 3
  dt = 0.02
[]

(test/tests/mechanics/mech3d.i)

[Domain]
  dim = 3
  nx = 16
  ny = 16
  nz = 16
  xmax = ${fparse 2*pi}
  ymax = ${fparse 2*pi}
  zmax = ${fparse 2*pi}
  mesh_mode = DUMMY
  parallel_mode = FFT_AUTO
[]

[TensorComputes]
  [Initialize]
    [phase]
      type = ParsedCompute
      expression = '(cos(x)/2+0.5)^1*(cos(y)/2+0.5)^1*(cos(z)/2+0.5)^1'
      extra_symbols = true
      buffer = phase
    []
    [K]
      type = ParsedCompute
      buffer = K
      expression = '(1-phase)*Ka + phase*Kb'
      inputs = phase
      constant_names = 'Ka Kb'
      constant_expressions = '1 10'
    []
    [mu]
      type = ParsedCompute
      buffer = mu
      expression = '(1-phase)*mua + phase*mub'
      inputs = phase
      constant_names = 'mua mub'
      constant_expressions = '0.5 5'
    []
    [Finit]
      type = RankTwoIdentity
      buffer = F
    []
  []

  [Solve]
    [hyper_elasticity]
      type = HyperElasticIsotropic
      buffer = stress
      F = Fnew
      K = K
      mu = mu
    []

    [root]
      [applied_strain]
        type = MacroscopicShearTensor
        buffer = applied_strain
      []
      [mech]
        type = FFTMechanics
        buffer = Fnew
        F = F
        K = K
        mu = mu
        l_tol = 1e-2
        nl_rel_tol = 2e-2
        nl_abs_tol = 2e-2
        constitutive_model = hyper_elasticity
        stress = stress
        applied_macroscopic_strain = applied_strain
      []
    []
  []

  [Postprocess]
    [displacements]
      type = ComputeDisplacements
      buffer = disp
      F = F
    []
    [vonmises]
      type = ComputeVonMisesStress
      buffer = sV
    []
  []
[]

[TensorSolver]
  # no variables are integrated by this solver (FFTMechanics performs a steady state mechanics solve)
  type = ForwardEulerSolver
  root_compute = root
  # deformation tensor is just forwarded Fnew -> F
  forward_buffer = F
  forward_buffer_new = Fnew
  substeps = 10
[]

[TensorOutputs]
  active = 'parallel' # serial

  [serial]
    type = XDMFTensorOutput
    file_base = mech3d_serial
    buffer = 'disp sV F phase'
    output_mode = 'OVERSIZED_NODAL CELL CELL NODE'
    enable_hdf5 = true
    execute_on = 'TIMESTEP_END'
  []
  [parallel]
    # NODE and OVERSIZED_NODAL are not yet available in parallel output
    type = XDMFTensorOutput
    file_base = mech3d_parallel
    buffer = 'sV F phase'
    output_mode = 'CELL CELL CELL'
    enable_hdf5 = true
    execute_on = 'TIMESTEP_END'
  []
[]

[Executioner]
  type = Transient
  num_steps = 3
  dt = 0.01
[]

Overview
Example Input File Syntax
Input Parameters
Input Files