LinearNodalConstraint

Constrains slave node to move as a linear combination of master nodes.

The LinearNodalConstraint class constrains the slave node to move as a linear combination of master nodes. Master node ids and corresponding weights are taken as input along with the slave node set or slave node ids. This nodal constraint can be enforced either using the penalty formulation or the kinematic formulation.

Input Parameters

masterThe master node IDs.
C++ Type:std::vector
Options:
Description:The master node IDs.
penaltyThe penalty used for the boundary term
C++ Type:double
Options:
Description:The penalty used for the boundary term
variableThe name of the variable that this constraint is applied to.
C++ Type:NonlinearVariableName
Options:
Description:The name of the variable that this constraint is applied to.
weightsThe weights associated with the master node ids. Must be of the same size as master nodes
C++ Type:std::vector
Options:
Description:The weights associated with the master node ids. Must be of the same size as master nodes

Required Parameters

execute_onLINEARThe 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:LINEAR
C++ Type:ExecFlagEnum
Options:NONE INITIAL LINEAR NONLINEAR TIMESTEP_END TIMESTEP_BEGIN FINAL CUSTOM
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.
formulationpenaltyFormulation used to calculate constraint - penalty or kinematic.
Default:penalty
C++ Type:MooseEnum
Options:penalty kinematic
Description:Formulation used to calculate constraint - penalty or kinematic.
slave_node_idsThe list of slave node ids
C++ Type:std::vector
Options:
Description:The list of slave node ids
slave_node_setNaNThe boundary ID associated with the slave side
Default:NaN
C++ Type:BoundaryName
Options:
Description:The boundary ID associated with the slave side

Optional Parameters

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.
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

extra_matrix_tagsThe extra tags for the matrices this Kernel should fill
C++ Type:std::vector
Options:
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
Options:
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
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
Description:The tag for the vectors this Kernel should fill

Tagging Parameters

Input Files

modules/tensor_mechanics/test/tests/dynamics/linear_constraint/disp_mid.i

modules/tensor_mechanics/test/tests/dynamics/linear_constraint/disp_mid.i

# Constraining slave nodes to move a linear combination of master nodes
#
# The test consists of a 2D rectangular block divided into two Quad elements
# (along its height) which have different material properties.
# A displacement of 2 m is applied to the top surface of the block in x direction and the
# bottom surface is held fixed.
# The nodes of the interface between the two elements will tend to move as
# dictated by the material models of the two elements.

# LinearNodalConstraint forces the interface nodes to move as a linear combination
# of the nodes on the top and bottom of the block.
# master node ids and the corresponding weights are taken as input by the LinearNodalConstraint
# along with the slave node set or slave node ids.
# The constraint can be applied using either penalty or kinematic formulation.

# In this example, the final x displacement of the top surface is 2m and bottom surface is 0m.
# Therefore, the final x displacement of the interface nodes would be 0.25*top+0.75*bottom = 0.5m

[Mesh]
  file=rect_mid.e
[]


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

[Kernels]
  [./TensorMechanics]
    displacements = 'disp_x disp_y'
  [../]
[]

[BCs]
  [./top_2x]
    type = DirichletBC
    variable = disp_x
    boundary = 10
    value = 2.0
  [../]
  [./top_2y]
    type = DirichletBC
    variable = disp_y
    boundary = 10
    value = 0.0
  [../]
  [./bottom_1]
    type = DirichletBC
    variable = disp_y
    boundary = 1
    value = 0.0
  [../]
  [./bottom_2]
    type = DirichletBC
    variable = disp_x
    boundary = 1
    value = 0.0
  [../]
[]

[Materials]
  [./Elasticity_tensor_1]
    type = ComputeElasticityTensor
    block = 1
    fill_method = 'symmetric_isotropic'
    C_ijkl = '400. 200.'
  [../]

  [./strain_1]
    type = ComputeSmallStrain
    block = 1
    displacements = 'disp_x disp_y'
  [../]

  [./stress_1]
    type = ComputeLinearElasticStress
    block = 1
  [../]

  [./density_1]
    type = GenericConstantMaterial
    block = 1
    prop_names = 'density'
    prop_values = '10.'
  [../]

  [./Elasticity_tensor_2]
    type = ComputeElasticityTensor
    block = 2
    fill_method = 'symmetric_isotropic'
    C_ijkl = '1000. 500.'
  [../]

  [./strain_2]
    type = ComputeSmallStrain
    block = 2
    displacements = 'disp_x disp_y'
  [../]

  [./stress_2]
    type = ComputeLinearElasticStress
    block = 2
  [../]

  [./density_2]
    type = GenericConstantMaterial
    block = 2
    prop_names = 'density'
    prop_values = '10.'
  [../]

[]

[Executioner]
  type = Steady
  solve_type = 'PJFNK'
  petsc_options_iname = ''
  petsc_options_value = ''
  line_search = 'none'
[]

[Constraints]
  [./disp_x_1]
    type = LinearNodalConstraint
    variable = disp_x
    master = '0 5'
    weights = '0.25 0.75'
#    slave_node_set = '2'
    slave_node_ids = '2 3'
    penalty = 1e8
    formulation = kinematic
  [../]
  [./disp_y_1]
    type = LinearNodalConstraint
    variable = disp_y
    master = '0 5'
    weights = '0.25 0.75'
#    slave_node_set = '2'
    slave_node_ids = '2 3'
    penalty = 1e8
    formulation = kinematic
  [../]
[]

[Postprocessors]
  [./_dt]
    type = TimestepSize
  [../]
  [./disp_1]
    type = NodalVariableValue
    nodeid = 0
    variable = disp_x
  [../]
  [./disp_2]
    type = NodalVariableValue
    nodeid = 1
    variable = disp_x
  [../]
  [./disp_3]
    type = NodalVariableValue
    nodeid = 2
    variable = disp_x
  [../]
  [./disp_4]
    type = NodalVariableValue
    nodeid = 3
    variable = disp_x
  [../]
  [./disp_5]
    type = NodalVariableValue
    nodeid = 4
    variable = disp_x
  [../]
  [./disp_6]
    type = NodalVariableValue
    nodeid = 5
    variable = disp_x
  [../]
[]

[Outputs]
  exodus = true
  print_linear_residuals = true
  perf_graph = true
  [./console]
    type = Console
    output_linear = true
  [../]
[]

References

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