How to compute the strain energy density (... is not defined on block 0) ?

[zhenhao2049]

Check these boxes if you have followed the posting rules.

• Q&A General is the most appropriate section for my question
• I have consulted the posting Guidelines on the Discussions front page
• I have searched the Discussions forum and my question has not been asked before
• I have searched the MOOSE website and the documentation does not answer my question
• I have formatted my post following the posting guidelines (screenshots as a last resort, triple back quotes around pasted text)

Question

Hello everyone, I would like to ask a question regarding the computation of strain energy (as well as auxiliary variables such as von Mises stress). I have defined the ‘vonmises' and 'strain_energy_density' variables separately in AuxVariables and AuxKernels, and then I computed the strain energy in 'Materials'. I encountered the issue "... is not defined on block 0", how should I correct it? Thank you.

*** ERROR ***
The following occurred in the Problem 'MOOSE Problem' of type FEProblem.

Material property 'stress', requested by 'strain_energy_density' is not defined on block 0
Material property 'stress', requested by 'vonmises_aux' is not defined on block 0

I have attached the links for StrainEnergyDensity and RankTwoScalarAux.

https://mooseframework.inl.gov/source/materials/StrainEnergyDensity.html
https://mooseframework.inl.gov/source/auxscalarkernels/RankTwoScalarAux.html

And I have also attached my current input file.

# ==== Global Constant Parameters ====
concentrated_force = -100

# Global geo and mesh paras
geox = 1.0
geoy = 0.5
elemx = 40
elemy = 20
total_nodes = 861

# Global material paras
E0_val = 100e9  # elastic modulus
v0_val = 0.3    # possion's ratio

[GlobalParams]
  displacements = 'disp_x disp_y'
[]

# 创建正交网络
[Mesh]
  [generated]
    type = GeneratedMeshGenerator
    dim = 2  # 二维网格生成
    nx = ${elemx}  # nx,ny为两个方向的网格数量
    ny = ${elemy}
    xmax = ${geox}  # x,y方向的几何尺寸
    ymax = ${geoy}
  []

  [right_center_point]
    type = ExtraNodesetGenerator
    input = generated
    new_boundary = 'right_center'
    coord = '1.0 0.25 0'  # (xmax, ymax, 0)
    tolerance = 1e-8  # 坐标匹配容差
  []
[]

# Compute/Store intermediate quantities that are not the main variables
[AuxVariables]
  [levelset]
    # levelset function field (Input from python)
    order = FIRST
    family = MONOMIAL
  []

  [vonmises]
    # von-Mises stress
    order = FIRST
    family = MONOMIAL
  []

  [sed]
    # strain energy density
    order = FIRST
    family = MONOMIAL
  []
[]

[AuxKernels]
  [levelset_aux]
    type = FunctionAux
    variable = levelset           # 目标变量
    function = levelset_function  # 源函数
    execute_on = 'INITIAL'
  []

  [vonmises_aux]
    type = RankTwoScalarAux
    rank_two_tensor = stress
    variable = vonmises
    scalar_type = VonMisesStress   # 选择该Kernel中的计算项
    execute_on = 'TIMESTEP_END'    # 在后处理器运行前执行
  []

  [sed_aux]
    type = MaterialRealAux
    variable = sed
    property = strain_energy_density  # [Materials]中计算的属性
    execute_on = 'TIMESTEP_END'
  []
[]

[UserObjects]
  [levelset_reader]
    type = PropertyReadFile
    prop_file_name  = 'levelset_data.csv'
    read_type = 'voronoi'  # 说明数据是基于(x,y)坐标?? 'node'??
    nprop = 3
    nvoronoi = ${nvoronoi_param}  # 这里是CSV文件中的数据行数, 由python交互获取
  []
[]

[Functions]
  [levelset_function]
    type = PiecewiseConstantFromCSV
    read_prop_user_object = 'levelset_reader'  # 链接至UserObject
    read_type = 'voronoi'  # 和UserObjects保持一致
    column_number = '2'
  []
[]


[Physics/SolidMechanics/QuasiStatic]
  [all]
    strain = SMALL
    add_variables = true  # Add the variables from the displacement string in GlobalParams
    new_system = true
    formulation = TOTAL
    generate_output = 'cauchy_stress_xx cauchy_stress_yy cauchy_stress_zz cauchy_stress_xy '
                      'strain_xx strain_yy strain_zz strain_xy'
  []
[]

[Materials]
  [elasticity_tensor]
    # 属于AuxKernels里的Solid Mechanics App
    type = ComputeIsotropicElasticityTensor
    youngs_modulus = ${E0_val}  # 杨氏模量
    poissons_ratio = ${v0_val}  # 泊松比
  []

  [stress]
    type = ComputeLagrangianLinearElasticStress
  []

  [strain_energy_density]
    type = StrainEnergyDensity
    incremental = false
  []

  [pseudo_density_from_levelset]
    type = ParsedMaterial
    property_name = pseudo_density
    coupled_variables = 'levelset'
    expression = 'levelset'  # levelset范围为0-1
  []

  [E_eff]
    type = ParsedMaterial
    property_name = E_eff
    material_property_names = 'pseudo_density'
    expression = 'E0 * pseudo_density^p + Emin'  # SIMP-like插值
    constant_names = 'E0 Emin p'
    constant_expressions = '${E0_val} 1e3 3.0'  # E0=弹性模量, Emin=避免奇异, p=惩罚因子
  []
[]

[BCs]
  [fix_x]
    type = DirichletBC
    boundary = 'left'
    value = 0
    variable = disp_x
  []
  [fix_y]
    type = DirichletBC
    boundary = 'left'
    value = 0
    variable = disp_y
  []
[]

[NodalKernels]
  # Apply concentrated force at middle of right boundary
  [force_y]
    type = ConstantRate
    variable = disp_y
    boundary = right_center  # [Mesh block中定义节点集]
    rate = ${concentrated_force}  # [集中载荷]
  []
[]

# 求解器和输出
[Executioner]
  type = Steady
  solve_type = NEWTON
  
  petsc_options_iname = '-pc_type -pc_factor_mat_solver_package'
  petsc_options_value = 'lu       mumps'

  # Nonlinear solver
  nl_rel_tol = 1e-6   # Relative tolerance
  nl_abs_tol = 1e-8   # Absolute tolerance
  nl_max_its = 50     # Max Nonlinear Iterations

  # Linear solver
  l_tol = 1e-5
  l_max_its = 100

  automatic_scaling = true
[]

[Outputs]
  [csv]
    type = CSV  # output csv to python
    file_base = eval_output
    execute_on = 'TIMESTEP_END'
  []

  # 定期输出VTK用于可视化
  [vtk]
    type = VTK
    interval = 20
  []

  exodus = false
[]

[Postprocessors]
  [volume_fraction]
    # 积分材料属性 - 在所有单元上对某个材料属性进行一次积分
    type = ElementIntegralMaterialProperty
    mat_prop = pseudo_density
    execute_on = 'TIMESTEP_END'
  []

  # Optimization target one: compliance
  [compliance]
    type = ElementIntegralMaterialProperty
    mat_prop = strain_energy_density
    execute_on = 'TIMESTEP_END'
  []

  # Optimization target two: Stress uniformity???
  [vonmises]
    type = ElementAverageValue
    variable = vonmises
  []
[]

[GiudGiud]

Hello

This is likely due to prefixes in the names of material properties
Use debug/show_material_props=true from this action
https://mooseframework.inl.gov/source/actions/SetupDebugAction.html

to see all the names used by the materials declaring the properties. Then you can use those names to refer to the property in objects consuming these material properties

[zhenhao2049]

Thank you very much for your suggestion. I have solved my problem. The stress name in the module is "cauchy_stress".