# Linear Viscoelasticity Manager

Manages the updating of the semi-implicit single-step first-order finite difference time-stepping scheme

## Description

This updates the internal time-stepping scheme for linear viscoelastic materials (such as a GeneralizedKelvinVoigtModel or a GeneralizedMaxwellModel material) at the beginning of each time step. Including a LinearViscoelasticStressUpdate in the simulation is required for the linear viscoelastic strains to be updated properly.

## Example Input File Syntax

[./update]
type = LinearViscoelasticityManager
viscoelastic_model = kelvin_voigt
[../]

(modules/tensor_mechanics/test/tests/visco/visco_finite_strain.i)

## Input Parameters

• viscoelastic_modelname of the LinearViscoelasticityBase object to manage

C++ Type:std::string

Options:

Description:name of the LinearViscoelasticityBase object to manage

### Required Parameters

• elastic_strain_nameelastic_strainname of the elastic strain tensor used for the viscoelastic update

Default:elastic_strain

C++ Type:std::string

Options:

Description:name of the elastic strain tensor used for the viscoelastic update

• creep_strain_namecreep_strainname of the creep strain tensor used for the viscoelastic update

Default:creep_strain

C++ Type:std::string

Options:

Description:name of the creep strain tensor used for the viscoelastic update

• stress_namestressname of the stress tensor used for the viscoelastic update

Default:stress

C++ Type:std::string

Options:

Description:name of the stress tensor used for the viscoelastic update

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

C++ Type:std::vector

Options:

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

### Optional Parameters

• 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.

• 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.

• allow_duplicate_execution_on_initialFalseIn the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).

Default:False

C++ Type:bool

Options:

Description:In the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).

• seed0The seed for the master random number generator

Default:0

C++ Type:unsigned int

Options:

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

Options:

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