Design constraints in design sensitivity analysis

A design constraint identifies which aspect of a model to analyze for sensitivity. For example, you might want to know the effect that modifying the mass density of a particular material might have on the first natural frequency of the model. In this case, the design constraint would be the first normal mode for a normal modes subcase. Design constraints can include the model's volume, weight, normal modes, and modal frequencies.

Each design sensitivity analysis (DSA) solution must have at least one design constraint. If you do not create a design constraint at the solution level, you must create one for each subcase in the solution. You can optionally use multiple design constraints for each solution or subcase.

You can use a design constraint for weight or volume only at the solution level. For all other responses—such as normal modes or acoustic pressure—you must create the design constraint at the subcase level.

Note:

Any limits specified for a design constraint are not used in a design sensitivity analysis. For example, if you create a design constraint for weight, any lower or upper bound is ignored.

Creating design constraints

Each design constraint is a modeling object. You can create design constraints using the following approaches:

• Use the Modeling Objects command.For a DSA design constraint, you can use any of the following modeling object types:Design Constraint - GlobalDesign Constraint - Modal FrequencyDesign Constraint - Normal ModesWhen you use the Modeling Objects command, the design constraint appears only under the Modeling Objects node in the Simulation Navigator. To apply it to your DSA solution, you must either right-click the modeling object and choose Add to Active Solution or Step, or drag the modeling object from the Modeling Objects node to the Design Constraint node for the solution or subcase. You can use the Add to Active Solution or Step command only if the solution or subcase is active, but you can drag a modeling object to the Design Constraint node at any time.You can use a global design constraint only at the solution level. You can use the others only with the corresponding subcase. For example, you can use a normal modes design constraint only with a DSA - Normal Modes subcase.

• In the Simulation Navigator, right-click the Design Constraint node under a DSA solution or subcase and choose New Design Constraint.You can add a solution-level design constraint only when the solution is active. If the solution is active, you can add a subcase-level design constraint even if the subcase is not active.This approach adds the modeling object under both the selected Design Constraint node and the Modeling Objects node.

Working with design constraints

• To see the information that is sent to the solver when you solve the solution, right-click the design constraint and choose Solver Syntax Preview.

• To remove a design constraint from a solution or subcase, right-click the design constraint and choose Remove. To remove all of the design constraints, right-click the Design Constraint node and choose Remove All.You can remove a design constraint only when the solution is active.Removing a design constraint from a solution or subcase does not delete the modeling object, so you can restore it later.

Where do I find it?

Application	Pre/Post
Prerequisite	A Simulation file as the work part and displayed part
Command Finder	Modeling Objects
Simulation Navigator	Right-click the Design Constraint node under the solution or subcase→New Design Constraint

Design constraints in design sensitivity analysis, Simcenter 3D 2021.1 Series

© 2020 Siemens

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