ComputeNeoHookeanStress

Stress update based on the first Piola-Kirchhoff stress

Overview

This class provides a hyperelastic Neo-Hookean stress update defining the 2nd Piola-Kirchhoff stress as with where is the Green-Lagrange strain. The model is then defined in terms of two parameters, and .

For small strains, when large_kinematics = false the model instead returns the standard linear elastic response, taking the and parameters to be the Lame parameters defining a small strain theory elastic model.

Figure 1 shows a typical material response under uniaxial stress. The plot shows the results in terms of the Cauchy stress and logarithmic strain to illustrate that the large deformation version of the model is in fact nonlinear.

Figure 1: Response of the Neo-Hookean model to uniaxial deformation, plotted as log strain versus Cauchy stress.

Example Input File Syntax

The follow example configures a large deformation Neo-Hookean model with and .

[Materials]
  [compute_stress]
    type = ComputeNeoHookeanStress
    lambda = 4000.0
    mu = 6700.0
  []
  [compute_strain]
    type = ComputeLagrangianStrain
  []
[]
(moose/modules/tensor_mechanics/test/tests/lagrangian/materials/correctness/neohookean.i)

Input Parameters

  • base_nameMaterial property base name

    C++ Type:std::string

    Controllable:No

    Description:Material property base name

  • blockThe list of blocks (ids or names) that this object will be applied

    C++ Type:std::vector<SubdomainName>

    Controllable:No

    Description:The list of blocks (ids or names) that this object will be applied

  • boundaryThe list of boundaries (ids or names) from the mesh where this object applies

    C++ Type:std::vector<BoundaryName>

    Controllable:No

    Description:The list of boundaries (ids or names) from the mesh where this object applies

  • computeTrueWhen false, MOOSE will not call compute methods on this material. The user must call computeProperties() after retrieving the MaterialBase via MaterialBasePropertyInterface::getMaterialBase(). Non-computed MaterialBases are not sorted for dependencies.

    Default:True

    C++ Type:bool

    Controllable:No

    Description:When false, MOOSE will not call compute methods on this material. The user must call computeProperties() after retrieving the MaterialBase via MaterialBasePropertyInterface::getMaterialBase(). Non-computed MaterialBases are not sorted for dependencies.

  • constant_onNONEWhen ELEMENT, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps.When SUBDOMAIN, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps. Evaluations on element qps will be skipped

    Default:NONE

    C++ Type:MooseEnum

    Options:NONE, ELEMENT, SUBDOMAIN

    Controllable:No

    Description:When ELEMENT, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps.When SUBDOMAIN, MOOSE will only call computeQpProperties() for the 0th quadrature point, and then copy that value to the other qps. Evaluations on element qps will be skipped

  • declare_suffixAn optional suffix parameter that can be appended to any declared properties. The suffix will be prepended with a '_' character.

    C++ Type:MaterialPropertyName

    Controllable:No

    Description:An optional suffix parameter that can be appended to any declared properties. The suffix will be prepended with a '_' character.

  • lambdalambdaParameter conjugate to Lame parameter for small deformations

    Default:lambda

    C++ Type:MaterialPropertyName

    Controllable:No

    Description:Parameter conjugate to Lame parameter for small deformations

  • large_kinematicsFalseUse a large displacement stress update.

    Default:False

    C++ Type:bool

    Controllable:No

    Description:Use a large displacement stress update.

  • mumuParameter conjugate to Lame parameter for small deformations

    Default:mu

    C++ Type:MaterialPropertyName

    Controllable:No

    Description:Parameter conjugate to Lame parameter for small deformations

  • prop_getter_suffixAn optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.

    C++ Type:MaterialPropertyName

    Controllable:No

    Description:An optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.

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: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

  • output_propertiesList of material properties, from this material, to output (outputs must also be defined to an output type)

    C++ Type:std::vector<std::string>

    Controllable:No

    Description:List of material properties, from this material, to output (outputs must also be defined to an output type)

  • outputsnone Vector of output names where you would like to restrict the output of variables(s) associated with this object

    Default:none

    C++ Type:std::vector<OutputName>

    Controllable:No

    Description:Vector of output names where you would like to restrict the output of variables(s) associated with this object

Outputs Parameters