Couple_freedoms
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Data Structure: Couple_freedoms |
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Coupled freedom data structure |
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Couple_freedoms NUM=ival where ival is the data structure number |
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Overview The Couple_freedoms data structure defines either: •Set Type: "Standard" - A list of geometry entities where the displacement of one or more freedoms is constant for all nodes on the geometry; e.g. to enforce a line to remain plane in 2-D or a surface to remain plane in 3-D. •Set Type: "Geometry" - Two lists of geometry entities which are joined together using a master slave relationship.
Notes •Several coupled freedom data structures may defined. •See the reference manual page Tied Contact (Master-Slave) for more detailed information on the master-slave coupling.
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 | Active_flag Coupled freedom active flag |
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Defines whether the coupled freedom set is active. Generally not required as it is set by default. Valid values are: •-1 - Deactivate and remove if defined • 0 - Not defined • 1 - Defined and active (Default)
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| Node_to_node_flag Node to node coupling flag |
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Node_to_node_flag is a keyword relevant to application of Couple_freedoms to approach tied surfaces ( Set_type "Geometry"). It defines whether the coupling is performed node to node or node to facet. Valid values are: • 0 - Node to facet (Default. Available for sequential analysis only) • 1 - Node to node (Requires matching meshes. Available for parallel analysis with explicit geomechanics)
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| Set_type The type of coupled freedom set |
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Specifies the type of coupled freedom set. Valid set types are: • "Standard" - where a point/node within a geometry entity becomes the master node and is used to set the displacements to the remaining (slave) points/nodes within the geometry entity to be constant. This is often used to ensure that a boundary remains flat during the entire simulation. • "Geometry" - where two sets of geometry entities are tied, sharing the same displacements in all directions using a master-slave approach.
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| Geomechanical_codes Couple freedom code for each freedom in the geomechanical field |
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Defines whether or not the displacements in each direction (X Y in 2D and X Y Z in 3D) are coupled for the geometry entity. Valid values are: •0 - Free (direction not coupled) •1 - Coupled
For example in order to use Couple_freedoms to maintain flat the top surface in a 3D model Geomechanical_codes will have IDM =3 and the values will be defined as 0 0 1 so that only vertical displacement (z) is coupled.
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| Master_point Master geometry point (optional) |
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Defines the geometry point number that is the master in Couple_freedoms type "Standard". If not specified the master point will be automatically selected as the first geometry point in the defined geometry entity list.
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| Master_node Master node (optional) |
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Defines the master node number for Couple_freedoms type "Standard". If not specified then Master_node is evaluated as the first node in the defined geometry entity list.
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| Volumes Coupled freedom volume assignments |
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The Volumes keyword assigns the coupled freedom set to individual volumes.
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| Surfaces Coupled freedom surface assignments |
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The Surfaces keyword assigns the coupled freedom set to individual surfaces.
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| Lines Coupled freedom line assignments |
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The Lines keyword assigns the coupled freedom set to individual lines.
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| Points Coupled freedom point assignments |
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The Points keyword assigns the coupled freedom set to individual points.
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| Geometry_sets List of geometry sets with coupled freedom assignments |
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The Geometry_sets keyword assigns the coupled freedom set to individual geometry sets.
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| Master_surfaces List of Master surfaces with coupled freedom assignments |
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The Master_surfaces keyword assigns the coupled freedom set to individual master surface. It is used when two surfaces with different meshes are coupled together. Each surface in the list is coupled to a surface in the same location in the Slave_surfaces list.
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| Slave_surfaces List of slave surfaces with coupled freedom assignments |
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The Slave_surfaces keyword assigns the coupled freedom set to individual slave surface. It is used when two surfaces with different meshes are coupled together. Each surface in the list is coupled to a surface in the same location in the Master_surfaces list.
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| Master_lines List of Master lines with coupled freedom assignments |
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The Master_lines keyword assigns the coupled freedom set to individual master line. It is used when two lines with different meshes are coupled together. Each line in the list is coupled to a line in the same location in the Slave_lines list.
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| Slave_lines List of slave lines with coupled freedom assignments |
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The Slave_lines keyword assigns the coupled freedom set to individual slave line. It is used when two lines with different meshes are coupled together. Each line in the list is coupled to a line in the same location in the Master_lines list.
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| Master_geometry_sets List of geometry sets with coupled freedom assignments |
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The Master_geometry_sets keyword assigns the coupled freedom set to individual geometry sets. It is used when two geometry sets with different meshes are coupled together. Each geometry set in the list is coupled to a geometry set in the same location in the Slave_geometry_sets list.
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| Slave_geometry_sets List of geometry sets with coupled freedom assignments |
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The Slave_geometry_sets keyword assigns the coupled freedom set to individual geometry sets. It is used when two geometry sets with different meshes are coupled together. Each geometry set in the list is coupled to a geometry set in the same location in the Master_geometry_sets list.
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| Proximity_tolerance Tolerance for the allowable distance of a slave node from a master facet |
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Defines a proximity tolerance for a slave node from the master surface facet for master-slave surfaces. The maximum allowable distance is tol * "facet characteristic length". By default a distance tolerance is not used.
Notes •Only one value of Proximity_tolerance can be used for all sets. Consequently it only needs to be specified on one set
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| Boundary_tolerance Tolerance for inside element check on boundaries |
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1\k Boundary_tolerance is a non-dimensional tolerance (default 0.001) for assessing whether a node is inside a facet for the master-salve algorithm. It is primary active on model boundaries where a node coincideent with an element boundary, particularly on curved boundaries may lie just outside the facet. Generally the default value is appropriate.
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