Optimization Module Updates

For users of the Optimization Module, COMSOL Multiphysics® version 6.1 provides milling constraints for topology optimization, improved support for preserving the continuity of curves and surfaces for shape optimization, and a new feature for the shape optimization of eigenfrequencies for structural shells. Read more about these features below.

Manufacturing Constraints for Topology Optimization

Topology optimization is associated with extreme design freedom. This can yield extreme performance but also complex geometry parts that are challenging to use in conventional manufacturing techniques. The existing Density Model feature now includes milling constraint functionality to ensure compatibility with conventional manufacturing techniques. You can see this feature in the new Topology Optimization of a Beam with Milling Constraints model and several updated structural mechanics models.

Topology optimization of a wheel is shown in the new Wheel Rim — Topology Optimization with Milling Constraints tutorial model. The full wheel is modeled, with sector symmetry imposed for the shape optimization. The wheel rim is optimized for stiffness with respect to 12 load cases, and the optimization includes milling constraints in the axial directions (left). The corresponding result without milling constraints is shown for reference (right).

Continuity for Shape Optimization

When performing shape optimization, preserving continuity of the normal vector is a way of maintaining smooth curves and surfaces in the optimized geometry model. The Free Shape Boundary and Free Shape Shell features have been extended with support for preserving the continuity of the normal vector over Symmetry and Roller boundaries as well as between the selection of different Free Shape Boundary and Free Shape Shell features. Similarly, the 2D versions of the Polynomial Boundary and Polynomial Shell features have been extended with support for preserving the continuity of the normal vector over Symmetry and Roller boundaries as well as between entities in the selection and next to fixed points. The Design Optimization of a Beam model has been updated to use this new functionality.

In addition, the Control Function feature now includes a Piecewise Bernstein polynomial option. For this control type, the slope is continuous between the polynomials. This is useful for increasing design freedom without introducing the high-frequency noise typically associated with higher-order polynomials.

The COMSOL Multiphysics UI showing the Model Builder with the Free Shape Boundary node highlighted, the corresponding Settings window, a fatigue model in the Graphics window, and the Objective Probe Table.
The new Wheel Rim — Stress Optimization with Fatigue Evaluation tutorial model demonstrates shape optimization of a wheel with respect to an approximation of the maximum stress. The full wheel is modeled, with sector symmetry imposed for the shape optimization. Furthermore, a finer mesh is used on the sector used for stress evaluation, and the settings for the Free Shape Boundary feature ensure continuity of the normal vector between sectors. The optimization considers 6 load cases and optimizes for the worst case while constraining the stiffness and mass to the initial values. This is a heuristic approach to fatigue optimization, so the fatigue properties are evaluated before and after the optimization.

Gradient-Based Optimization of Eigenfrequencies for Shells

Eigenfrequencies can now be subject to certain types of gradient-based optimizations and can, for example, be used for the shape optimization of structural shells. The existing Polynomial Boundary feature has been extended to support 3D, and a new Polynomial Shell feature has been added to the Shape Optimization interface. You can see a demonstration of this functionality in the new Maximizing the Eigenfrequency of a Shell tutorial model.

The COMSOL Multiphysics UI showing the Model Builder with the Optimization node highlighted, the corresponding Settings window, a shell model in the Graphics window, and the Objective Probe Table.
The Maximizing the Eigenfrequency of a Shell tutorial model demonstrates how to use the new Polynomial Shell feature to maximize the lowest eigenfrequency of a shell.

New and Updated Tutorial Models

COMSOL Multiphysics® version 6.1 brings several new and updated tutorial models to the Optimization Module.