Design objective

The design objective is your overall goal of the optimization problem. You choose to minimize or maximize a given attribute that is specified in a design response. An optimization solution can have only one design objective and response.

Examples of design objectives and responses include:

• Minimize weight

• Minimize a stress component for a single element

• Minimize displacement of a specific node in a specified direction

Caution:

A response defined for a design objective cannot represent multiple responses.

For example, for responses that affect a node, such as displacement, the Design Response dialog box lets you specify the node by referencing a group. Although groups can contain multiple nodes, you should reference only a single node in the response for a design objective.

Another example is the specification of a physical property table in a Stress response. Make sure the mesh collector that references the physical property table contains only a single element. If necessary, you can use the Element Extract command to move an element out of an existing mesh to create a single-element mesh.

If a response invokes multiple responses, the solver issues the following error and does not solve.

USER FATAL MESSAGE 7148 (DOPR3H) THE DESOBJ COMMAND WITH ID = 30 REFERENCES A DRESP1 ENTRY WHICH INVOKES MULTIPLE RESPONSES. USER INFORMATION: DRESP1 ENTRIES INVOLVED IN DEFINING THE OBJECTIVE MUST BE SCALAR QUANTITIES. 0FATAL ERROR

The design objective corresponds to the Simcenter Nastran DESOBJ case control command.

A design objective/response can be defined at the solution level or subcase level

• When you define the design objective in the solution attributes, the associated response is evaluated at every subcase.

• When you define the design objective in a subcase, the associated response is evaluated only in that subcase.

Where do I find it?

Application	Pre/Post
Prerequisite	A solution of type SOL 200 Design Optimization
Menu	Insert→Solution****Insert→Step-Subcase****Insert→Modeling Objects→Type=Design Objective
Location in dialog box	Solution dialog box→Case Control tab→Create Modeling Object Solution Step dialog box→Create Modeling Object

How do I

Create the design objective and response

Quick links

Command reference

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Design objective, Simcenter 3D 2021.1 Series

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