Configuring the perturbation settings

In the optimization task editor, click the Perturbation tab.

Enter the number of eigenmodes to track. The default value is five, which means that the Optimization module tracks the five lowest eigenfrequencies.

In some cases many local low frequency eigenmodes appear during the optimization iterations, which leads to a high number of modes to track and degrades performance. You can avoid tracking a high number of modes by choosing the lower bound of the eigenfrequencies to be 25% of the eigenfrequency of interest in the first optimization iteration.

Mode tracking is not required if your design response will use the Kreisselmaier-Steinhauser formulation to evaluate the eigenfrequencies. Your Abaqus model must include an output request for at least the number of eigenfrequencies you are tracking.

Select the region over which the Optimization module should track the eigenmodes.

By default, the Optimization module tracks the eigenmodes of all the nodes in the model, which can degrade performance if you have a large model. You can improve the performance by tracking the eigenmodes over only a selected region; for example, over selected surfaces of your model or over points where lumped or rigid masses are attached.