Design sensitivity analysis

A design sensitivity analysis (DSA) computes the effect (sensitivity) of certain changes on a model. 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.

Using either Simcenter Nastran or MSC Nastran, you can create a SOL 200 Design Sensitivity Analysis solution for either a structural or vibro-acoustic analysis. When you create this type of solution, you must specify at least one of each of the following:

• Design constraint, which identifies the aspect for which to analyze sensitivity.In the preceding example, the design constraint would be 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.

• Design variable, which lets you vary a particular quantity, such as the model's physical, composite, material, or connectivity property.In the preceding example, the design variable would be the RHO of the material in the model.

You can use this sensitivity information to perform parametric design studies.

Supported subcases

When you create a SOL 200 Design Sensitivity Analysis solution, you can create any number or combination of the following subcases:

• DSA - Normal ModesThe design constraint response types include eigenvalue and normal modes. You cannot directly add any boundary conditions to this type of subcase; they are inherited from the solution.

• DSA - Modal FrequencyFor a structural analysis, the design constraint response types include frequency response displacement, frequency response velocity, frequency response acceleration, frequency response force, frequency response single-point constraint force, and frequency response stress.A vibro-acoustic analysis supports all those response types as well as acoustic pressure.You can add a variety of loads to this type of subcase. For more information, see Simcenter Nastran and MSC Nastran boundary conditions.For a structural analysis, you can add a frequency load set. For a vibro-acoustic analysis, you can add a frequency excitation set or acoustic load set.

• DSA - Modal Frequency Response FunctionsFor this subcase type, the design constraint response types are the same as for DSA - Modal Frequency. However, the only load you can use with this subcase is unit force.

Import considerations

You can import a .dat or .op2 file as a SOL 200 Design Sensitivity Analysis solution when DSAPRT(END=SENS) is present in the case control and only MODE or MFREQ subcases are present.

For an MFREQ subcase, the type of subcase created during the import depends on the settings associated with that subcase:

Settings	Subcase type
PARAM,FRFGEN,NO is present in the bulk dataorPARAM,FRFGEN is not present in the bulk data	DSA- Modal Frequency
PARAM,FRFGEN,YES is present in the bulk dataorPARAM,FRFSUB in present in the SUBCASE	DSA - Modal Frequency Response Functions

Note:

When a DSA - Modal Frequency Response Functions subcase is imported, the unit loads of the various subcases are not compacted.

Where do I find it?

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter Nastran or MSC Nastran as the specified solverStructural or Vibro-Acoustic as the specified analysis typeSOL 200 Design Sensitivity Analysis as the specified solution type
Command Finder	Solution

Design sensitivity analysis, Simcenter 3D 2021.1 Series

© 2020 Siemens

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