Restricting the Absolute Displacement

This section gives information on the CHECK_SHRINK and CHECK_GROW design variable constraints.

See Also
In Other Guides
DVCON_BEAD

It is possible to specify a maximum allowable absolute displacement for each node in relation to the starting geometry.

The parameters


CHECK_GROW   = <max_grow_value>
CHECK_SHRINK = <max_SHRINK_value>

specifies a maximum absolute displacement <max_grow_value> allowed in the growth direction and <max_shrink_value> in the opposite direction.

Important:

The values must be positive.

In controller-based bead optimization, the maximum displacement amount of the design nodes is restricted in the constraint of the optimization task (see DRESP type "BEAD_HEIGHT" and CONSTRAINT). The definition of an additional restriction by the DVCON_BEAD command allows for the definition of additional restrictions on specified design nodes.

Important:

For the sensitivity-based algorithm, the DVCON_BEAD are the only restriction on the design nodes optimization displacement and must therefore be defined. If any node in the design area is not restricted, Tosca Structure will stop with an error.

The easiest way to constrain all design nodes is to use:


DVCON_BEAD
 ID_NAME       = MY_DVCON_BEAD
 ND_GROUP      = DESIGN_NODES
 CHECK_GROW    = 10.0
 CHECK_SHRINK  = 0.0
END_

The command above is equivalent to define the following BEAD_HEIGHT constraint in the controller-based algorithm. 


CONSTRAINT
 ID_NAME    = MY_BEAD_HEIGHT_CONSTRAINT
 DRESP      = BEAD_HEIGHT_DRESP
 EQ_VALUE   = 10.0
 MAGNITUDE  = ABS
END_

Realization in Tosca Structure.gui

  1. Choose Command > DVCON_BEAD.
  2. Example just described constraining all design nodes to a maximum growth of 10.0 and no shrink.