DVCON_TOPO

ID_NAME	= `<id_name_of_dvcon_topo>`	Name of the `DVCON_TOPO` definition
EL_GROUP	= `<name_of_element_group>`	Name of an element group already defined with which `DVCON_TOPO` should react.
CHECK_TYPE	= FROZEN	All elements of the element group `<name_of_element_group>` which do not undergo any changes during optimization.
	= CAST	Manufacturing restrictions to guarantee the manufacturing of the elements.
	= MIN_MEMBER	Minimum member size filter (definition of the minimum structural diameter).
	= MAX_MEMBER	Maximum member size filter (definition of the maximum structural diameter).
	= LINK_TOPO	Definition of symmetry and link conditions.
	= CLUSTER_GROUPS	Clustering of elements with the same design variable value. Several `EL_GROUP` items can be defined with this `CHECK_TYPE`.

Items for CHECK_TYPE = MIN_MEMBER

THICKNESS

= <thickness>

Minimum thickness of the structure.

Items for CHECK_TYPE = MAX_MEMBER

THICKNESS

= <thickness>

Maximum thickness of the structure.

DISTANCE

= <distance value>

= 0 (=automatically determined)

Distance between two supports for the maximum member size control.

MIN_THICKNESS

= <thickness>

= <value_of_THICKNESS>

Minimum thickness of the structure when using a maximum member size constraint. The resulting structures have a thickness between MIN_THICKNESS and THICKNESS.

Items for CHECK_TYPE = LINK_TOPO

CHECK_LINK	= `<name_of_link_topo>`	Reference of the corresponding `LINK_TOPO` definition.
RADIUS	= `<radius>`	Radius value: should be about 50% of the average element edge length, if specified.

Items for CHECK_TYPE = CAST

PULL_DIR	= `<X_COMP>`, `<Y_COMP>`, `<Z_COMP>`	Pull direction for the element groups in the form of a vector with reference to `CS_0`.
ANGLE	= `<draft_angle>` = 0°	Removal angle, 0°<= `ANGLE` < 20°.
CHECK_GROUP	= `<name_of_element_group>` = ALL_ELEMENTS	Name of the element group which is used for the collision check of the removed elements.
MID_PLANE	= NONE	No definition of a central plane, i.e. the elements are only deformed in the direction of `PULL_DIR`.
	= AUTO	Automatic determination of the central plane. Using the central plane as the starting point. The elements are removed either in the direction of the deformation or in the opposite direction.
	= AUTO_TIGHT	No holes are generated in the central plane.
	= POINT, `<X_COMP>`, `<Y_COMP>`, `<Z_COMP>`	A point within the central plane from which the deformation vector is positioned perpendicular to.
	= SURFACE	The elements are demolded at the actual surface of the `DVCON` group.
	= STAMP	The element group is demolded keeping a stampable structure.
PULL_CS	= `<name_of_coordinate_system>` = CS_0	Coordinate system for the definition of the pull direction. If a cylindrical coordinate system is referenced, the casting restrictions are performed in cylindrical coordinates. The command PULL_CS also defines the local coordinate system for the definition of the mid-plane point when MID_PLANE = POINT, x,y,z is used to define a demold control.
RADIUS	= `<radius>`	Radius value: should be about 50% of the average edge length of the element, if specified. (This value is used internally for the collision check during the removal of the elements). In Combination with `MIDPLANE=AUTO_TIGHT` the thickness of the midplane is defined by 2*`RADIUS`.
CREATE_PULL_GROUP	= YES	Element groups for the demolded elements are automatically generated.
	= NO	No element groups are generated.
FILTER_MAT	= NO = YES	Additional material based filtering after the optimization for stricter avoidance of undercuts.
FILTER_PARAM	= NO = YES	Alternative approach for demold constraints by parameterization of the design variables. Especially, for 2D models the optional setting is beneficial.

Items for CHECK_TYPE = CLUSTER_GROUPS

EL_GROUP

= <name_of_element_group>

Can be applied several times.

Remarks

The element group which should be restricted must be a subset of the referenced element group of DV_TOPO, i.e. all elements that should to be restricted must lie in this design area.
A check group can be entered for CHECK_TYPE=CAST or the corresponding default value, see the above table, will be used. This can be an upper set of design variables and must contain the element group that needs to be restricted (operator EL_GROUP). The CHECK_GROUP is the element group which will be checked for collision with the elements which should be removed. If this group contains more elements than the optimization group, the elements outside the optimization group is considered to be a barrier, i.e. the elements in the optimization group cannot be deformed "over" these element. For example, if an engine bracket is optimized and if a part of the engine block is still retained in the analysis model, the check group should be restricted to the engine bracket because the engine block does not play a significant role for the casting restriction of the engine bracket during manufacture. If the engine bracket is connected to the engine, the engine block must be added to the CHECK_GROUP, otherwise elements from the optimization area will be removed that must be "drawn" from the engine block.
If no RADIUS is entered for CHECK_TYPE=CAST, the optimization system will decide the radius from the elements of the check group (CHECK_GROUP). The value is determined by the output of the command. (Specifying the value is only important for elements in a model that has very different magnitudes.)
If the option CREATE_PULL_GROUP is selected, the elements are grouped in the following element groups:
- Elements with a positive demold direction in the group POS_DIR_*
- Elements with a negative demold direction in the group NEG_DIR_*
- Elements without demolding in the group NO_PULL_*
- Elements of the mid plane in the group MID_PLANE_*
The combination of a minimum member size constraint and a maximum member size constraint is not allowed. Please use the MIN_THICKNESS parameter in the maximum member size constraint instead!
If no DISTANCE parameter is specified for CHECK_TYPE=MAX_MEMBER in general the distance between two supports will be at least the thickness value.
The maximum member size constraint can only be used with the sensitivity-based algorithm. Maximum member size constraints with the controller algorithm are not supported.
For a more strict avoidance of undercuts an additional material filter (FILTER_MAT = YES) can be switched on which is applied after each optimization cycle. The optimization result is changed based on purely geometric aspects. This may influence the objective values and even the convergence in a negative way. Thus apply only, if the standard casting restriction does not lead to sufficient results.
The option FILTER_MAT = YES is not compatible with the parting surface options MID_PLANE = AUTO_TIGHT and MID_PLANE = SURFACE and with a removal angle ( ANGLE ) different than 0°.
For CHECK_TYPE = CLUSTER_GROUPS multiple element groups can be assigned using EL_GROUP parameter several times.

Examples

DVCON_TOPO
 ID_NAME = my_dvcon_topo_01
 EL_GROUP = el_grp_startarea
 CHECK_TYPE = FROZEN
END_

DVCON_TOPO
 ID_NAME = my_dvcon_topo_02
 EL_GROUP = el_grp_cast
 CHECK_TYPE = CAST
 CHECK_GROUP = ALL_ELEMENTS
 PULL_DIR = 0.,0.,1.
 MID_PLANE = NONE
END_

DVCON_TOPO
 ID_NAME = my_dvcon_topo_03
 EL_GROUP = el_grp_max_member_size
 CHECK_TYPE = MAX_MEMBER
 THICKNESS = 10.
 MIN_THICKNESS = 2.
 DISTANCE = 20.
END_

DVCON_TOPO
 ID_NAME = my_dvcon_topo_04
 EL_GROUP = my_element_group1
 EL_GROUP = my_element_group2
 CHECK_TYPE = CLUSTER_GROUPS
END_