# TangentialNodalLMMechanicalContact

Similar to the TangentialMortarLMMechanicalContact object except the constraints are enforced pointwise at nodes instead of in an integral way using the mortar method. Some numerical experiments suggest that the pointwise method of enforcing tangential contact constraints displays worse non-linear convergence than the mortar method.

Implements the KKT conditions for frictional Coulomb contact using an NCP function. Requires that either the relative tangential velocity is zero or the tangential stress is equal to the friction coefficient times the normal contact pressure.

## Input Parameters

• contact_pressureThe contact pressure. If using LM, this should be the normal lagrange multiplier

C++ Type:std::vector

Options:

Description:The contact pressure. If using LM, this should be the normal lagrange multiplier

• disp_yThe y velocity

C++ Type:std::vector

Options:

Description:The y velocity

• muThe friction coefficient for the Coulomb friction law

C++ Type:double

Options:

Description:The friction coefficient for the Coulomb friction law

• 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.

### 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.

• k_abs10The smoothing parameter for the function used to approximate std::abs. The approximating function is courtesy of https://math.stackexchange.com/a/1115033/408963

Default:10

C++ Type:double

Options:

Description:The smoothing parameter for the function used to approximate std::abs. The approximating function is courtesy of https://math.stackexchange.com/a/1115033/408963

• ncp_function_typeminThe type of NCP function to use

Default:min

C++ Type:MooseEnum

Options:min fb

Description:The type of NCP function to use

• normal_smoothing_distanceDistance from edge in parametric coordinates over which to smooth contact normal

C++ Type:double

Options:

Description:Distance from edge in parametric coordinates over which to smooth contact normal

• normal_smoothing_methodMethod to use to smooth normals (edge_based|nodal_normal_based)

C++ Type:std::string

Options:

Description:Method to use to smooth normals (edge_based|nodal_normal_based)

• orderFIRSTThe finite element order used for projections

Default:FIRST

C++ Type:MooseEnum

Options:FIRST SECOND THIRD FOURTH

Description:The finite element order used for projections

• primaryThe boundary ID associated with the primary side

C++ Type:BoundaryName

Options:

Description:The boundary ID associated with the primary side

• primary_variableThe variable on the primary side of the domain

C++ Type:std::vector

Options:

Description:The variable on the primary side of the domain

• secondaryThe boundary ID associated with the secondary side

C++ Type:BoundaryName

Options:

Description:The boundary ID associated with the secondary side

• tangential_toleranceTangential distance to extend edges of contact surfaces

C++ Type:double

Options:

Description:Tangential distance to extend edges of contact surfaces

### 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_meshTrueWhether 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:True

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.

• 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