# Chromium Isotropic Plasticity Update

Calculates the plastic strain as a function of strain rate for pure chromium. Note: This material must be run in conjunction with ComputeMultipleInelasticStress.

## Description

ChromiumPlasticityUpdate calculates the plastic strain for chromium cladding materials as a function of temperature. This material must be run in conjunction with ComputeMultipleInelasticStress. The material model inherits from IsotropicPlasticityStressUpdate and sets the yield_stress_function internally based upon temperature. Then irradiation hardening is incorporated as a function of fast neutron fluence that increases the yield stress. The yield stress as a function of temperature is given by Wagih et al. (2018): (1) where is the yield stress (MPa) and is the temperature (K). Irradiation hardening is then included via: (2)

## Example Input Syntax


[./chromium_plasticity]
type = ChromiumPlasticityUpdate
block = '1 2 3 4'
temperature = temp
fast_neutron_fluence = fast_neutron_fluence
yield_stress = 1e-6 # is ignored
hardening_constant = 0.0
[../]

ChromiumPlasticityUpdate must be run in conjunction with the inelastic strain return mapping stress calculator as shown below:


[./stress]
type = ComputeMultipleInelasticStress
tangent_operator = elastic
inelastic_models = 'chromium_plasticity'
block = '1 2 3 4'
[../]

## Input Parameters

• fast_neutron_fluenceThe coupled fast neutron flux variable.

C++ Type:std::vector

Description:The coupled fast neutron flux variable.

• hardening_functionTrue stress as a function of plastic strain

C++ Type:FunctionName

Description:True stress as a function of plastic strain

• max_inelastic_increment0.0001The maximum inelastic strain increment allowed in a time step

Default:0.0001

C++ Type:double

Description:The maximum inelastic strain increment allowed in a time step

• temperatureCoupled Temperature

C++ Type:std::vector

Description:Coupled Temperature

• base_nameOptional parameter that defines a prefix for all material properties related to this stress update model. This allows for multiple models of the same type to be used without naming conflicts.

C++ Type:std::string

Description:Optional parameter that defines a prefix for all material properties related to this stress update model. This allows for multiple models of the same type to be used without naming conflicts.

• max_its30Maximum number of Newton iterations

Default:30

C++ Type:unsigned int

Description:Maximum number of Newton iterations

• yield_stress0The point at which plastic strain begins accumulating

Default:0

C++ Type:double

Description:The point at which plastic strain begins accumulating

• acceptable_multiplier10Factor applied to relative and absolute tolerance for acceptable convergence if iterations are no longer making progress

Default:10

C++ Type:double

Description:Factor applied to relative and absolute tolerance for acceptable convergence if iterations are no longer making progress

• relative_tolerance1e-08Relative convergence tolerance for Newton iteration

Default:1e-08

C++ Type:double

Description:Relative convergence tolerance for Newton iteration

• absolute_tolerance1e-11Absolute convergence tolerance for Newton iteration

Default:1e-11

C++ Type:double

Description:Absolute convergence tolerance for Newton iteration

• boundaryThe list of boundary IDs from the mesh where this boundary condition applies

C++ Type:std::vector

Description:The list of boundary IDs from the mesh where this boundary condition applies

• hardening_constant0Hardening slope

Default:0

C++ Type:double

Description:Hardening slope

• yield_stress_functionYield stress as a function of temperature

C++ Type:FunctionName

Description:Yield stress as a function of temperature

• blockThe list of block ids (SubdomainID) that this object will be applied

C++ Type:std::vector

Description:The list of block ids (SubdomainID) that this object will be applied

### Optional Parameters

• effective_inelastic_strain_nameeffective_plastic_strainName of the material property that stores the effective inelastic strain

Default:effective_plastic_strain

C++ Type:std::string

Description:Name of the material property that stores the effective inelastic strain

• enableTrueSet the enabled status of the MooseObject.

Default:True

C++ Type:bool

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

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.

• control_tagsAdds user-defined labels for accessing object parameters via control logic.

C++ Type:std::vector

Description:Adds user-defined labels for accessing object parameters via control logic.

• seed0The seed for the master random number generator

Default:0

C++ Type:unsigned int

Description:The seed for the master random number generator

• implicitTrueDetermines whether this object is calculated using an implicit or explicit form

Default:True

C++ Type:bool

Description:Determines whether this object is calculated using an implicit or explicit form

• 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 computeSubdomainProperties() 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

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 computeSubdomainProperties() for the 0th quadrature point, and then copy that value to the other qps. Evaluations on element qps will be skipped

• internal_solve_output_onon_errorWhen to output internal Newton solve information

Default:on_error

C++ Type:MooseEnum

Description:When to output internal Newton solve information

• internal_solve_full_iteration_historyFalseSet true to output full internal Newton iteration history at times determined by internal_solve_output_on. If false, only a summary is output.

Default:False

C++ Type:bool

Description:Set true to output full internal Newton iteration history at times determined by internal_solve_output_on. If false, only a summary is output.

### Debug Parameters

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

C++ Type:std::vector

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

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

Default:none

C++ Type:std::vector

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

### Outputs Parameters

• yield_stress_scale_factor1Scale factor to be applied to yield stress. Used for calibration and sensitivity studies

Default:1

C++ Type:double

Description:Scale factor to be applied to yield stress. Used for calibration and sensitivity studies