Optimization modeling objects

To set up an optimization analysis, you will create several modeling objects, each of which writes out a Nastran case control command or bulk data entry.

• Design Variables — The physical attributes in the FEM that the software can modify in its search for an improved design. It can vary physical properties, material properties, and element properties. The Design Variable modeling object also defines the relationship between a variable and the corresponding property of the model.In Nastran, this corresponds to the DESVAR and DVPREL1, DVMREL1, or DVCREL1 bulk data entries.

• Design Response Quantities — A definition that selects an output such as weight, stress, or displacement. Currently, Pre/Post supports DRESP1 type (first-level) responses.

• Design Objective — The overall single goal of the optimization problem. With the objective, you choose whether to minimize or maximize a particular design response. For example, you can minimize the weight of the model. The objective references a design response that is defined in a Design Response Quantities modeling object. In Nastran, the objective corresponds to the DESOBJ case control command.

• Design Constraints — The upper and lower bounds on the design responses. Each constraint references a design response that is defined in a Design Response Quantities modeling object. In Nastran, this corresponds to the DCONSTR bulk data entry.

• Design Optimization Parameters — Any additional parameters to control the analysis. In Nastran, this corresponds to options on the DOPTPRM bulk data entry.

The following graphic shows how the optimization solution uses these modeling objects.

The optimizer adjusts design variables as it searches for the optimum conditions, while working in the domain of the constraints and the objective. At specific times, this process updates the FE model with the current values of the design variables, and requests a finite element analysis, which includes a sensitivity analysis. From the analysis results, it then updates the optimization approximate model with current design responses and their gradients. Each loop through a finite element analysis and sensitivity analysis is called a design cycle.

How do I

Control the design optimization output

Learn more

Simcenter Nastran Design Optimization

Design optimization workflow

Design objective

Design variables

Design constraints in design optimization

Design responses

Design optimization results

Optimization spreadsheet

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

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Optimization modeling objects, Simcenter 3D 2021.1 Series

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