Defining Constraints

The constraint is necessary in order to put the limits for optimization displacements. Normally, optimization tasks have some restrictions. These restrictions limit the values of the design responses or linear combinations of the design responses. If the constraint is not fulfilled the optimization result is not feasible.

This task shows you how to:

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In Other Guides
CONSTRAINT

Define constraints in Tosca ANSA® environment

Before you begin: For the definition of a constraint the design response (DRESP) which should be constraint has to be defined previously. (For more information, see Define a Design Response in Tosca ANSA® environment)
  • Select CONSTRAINT > New > CENTER_OF_GRAVITY_CONSTRAINT .

Define constraints in Tosca Structure.gui

Before you begin: For the definition of a constraint the design response (DRESP) which should be constraint has to be defined previously (For more information, see Define a Design Response in Tosca Structure.gui).

  1. Select Command > CONSTRAINT.

    The CONSTRAINT menu appears on the right.

  2. In the CONSTRAINT menu, define a constraint with a previously defined design response as shown in the figure below:

Define constraints in Tosca Extension for ANSYS® Workbench

Before you begin: For the definition of a constraint the design response (DRESP) which should be constraint has to be defined previously. (For more information, see Define a Design Response in Tosca Extension for ANSYS® Workbench.)

  1. Add a constraint to the project by clicking Optimization > Constraint.

  2. Within this constraint, choose a previously defined design response and set the other desired settings:

SIMULIA Tosca Structure Parameter File

  1. A constraint definition is given as:

    CONSTRAINT
 ID_NAME  = <id_name>
 DRESP    = <DRESP> 
 MAGNITUDE = <magnitude> 
 EQ_VALUE = <eq-target>
 LE_VALUE  = <le-target>
 GE_VALUE = <ge-target>
END_

  2. The ID_NAME must be referenced in the OPTIMIZE command for the constraint to be activated. Only one of the constraint items EQ_VALUE, LE_VALUE and GE_VALUE may be defined. They define the constraint value Ψ.

    The figure below shows the normalized output of a constraint in Tosca Structure.view:

Note:

In the above plot CONSTRAINT_NORM are all constraints plotted, normalized. CONSTRAINT_NORM is a special normalization so all fulfilled constraints are < 1.0. This also applies to GE_EQUAL constraints.