> > Example 10: Topology Design with Frequency Constraints

Example 10: Topology Design with Frequency Constraints
Use the model subwoofer_cover.prt for this example.
Description
This example demonstrates how to use topology optimization to design a light and stiff structure with modal analysis.
Highlighted features
Minimize Mass Fraction, Modal Frequency constraints, Symmetry fabrication constraint, Extrusion fabrication constraint
Optimization problem statement
The following optimization problem will be created and solved:
Objective:
Minimize Mass Fraction
Subject to:
First Modal Frequency > 200 Hz
Second Modal Frequency > 200 Hz
Analysis
The example contains one analysis. The constraints are shown in the image below:
Analysis settings:
Eigenvalue method: SMS
Frequency search range: 0–1000
Number of modes to find: 6
Mode Tracking: No
Mesh control
Maximum element size: 8 mm
Topology region
References:
The component, excluding volume region 1 and 2, as shown in the image below:
Init. mass fraction: 0.5
When you use mass fraction as constraint, it is recommended to use the same constraint bound value as the initial mass fraction value.
Fabrication constraints:
Mirror Symmetry about the YZ plane of coordinate system WCS
Mirror Symmetry about the XZ plane of coordinate system WCS
Extrusion along Z axis of coordinate system WCS
Minimum Member Size: 16 mm
Design objective
Minimize Mass Fraction
Design constraints
First Modal Frequency > 200 Hz
Second Modal Frequency > 200 Hz
The reason we constrain the first two modal frequencies is that they are symmetric modes with same frequency values. The maximum displacement in two modes is at different locations, and all those locations need to be reinforced.
Optimization study
The study refers to the defined topology region, design objectives, and constraints