Restricting the amount of displacement (CHECK_GROW / CHECK_SHRINK)

Use the design variable constraints CHECK_GROW and CHECK_SHRINK to apply a box constraint on the design variables.

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DVCON_SHAPE

Applicable for Controller (SHAPE_CONTROLLER) Sensitivity (SHAPE_SENSITIVITY)
CHECK_GROW OK OK
CHECK_SHRINK OK OK

It is possible to specify a maximum allowed absolute optimization displacement for each node in relation to the starting geometry. This involves differentiating between growth (node is moved outwards) and shrinkage (node is moved inwards). This function can be used, for example, in the optimization of mold parts that require a specific minimum and maximum wall thickness to allow the component to be cast. The parameters 

    
      CHECK_GROW = <max_grow_value>
      CHECK_SHRINK = <max_shrink_value>

specify a maximum amount of displacement <max_grow_value> allowed in the growth direction and a maximum amount of displacement <max_shrink_value> allowed in the shrink direction. Both values must be positive and can be set in the GROW/SHRINK_CONTROL menu of Tosca ANSA® environment or the Displacement fields in Tosca Structure.gui. The following figure provides a graphic illustration of the allowed displacement area.



Important: The CHECK_GROW and CHECK_SHRINK restrictions can only be defined for surface nodes since only surface nodes exhibit a growth or shrinkage direction. If inner nodes are contained in the node group (ND_GROUP parameter), the DVCON_SHAPE definition will be rejected.

For sensitivity-based shape optimization it is recommended that you restrict all design nodes. Using CHECK_SHRINK and CHECK_GROW is an easy way to accomplish this task.