COMSOL Multiphysics^® 6.1 Release Highlights

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 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 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.

Exporting and Importing a Topology-Optimized Hook

In this topology optimization of a hook, the simulation finds the optimal material distribution when the structural part is subjected to two load cases. This previously available model has been updated to use the new milling constraints available in the Density Model feature.

Application Library Title:
hook_topology_optimization_stl
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Topology Optimization of a Torsion Sphere with Milling Constraints

This example is a benchmark for milling constraints and solves a torque topology optimization problem. Without milling constraints, the resulting shape is a closed sphere, but with milling constraints, the resulting shape is more complicated, as shown in the figure. The model optimizes the topology with four milling directions. Symmetry is used so that only two milling directions have to be considered.

Application Gallery Title:
torque_topology_optimization_milling
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Topology Optimization of a Step Thrust Bearing

Topology optimization is used to design a step thrust bearing capable of supporting a large load. Designs with different numbers of grooves can be identified by modifying the initial design. The result is verified with a body-fitted mesh.

Application Library Title:
step_thrust_bearing_topology_optimization
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Shape Optimization of a Step Thrust Bearing

Shape optimization is used to design a step thrust bearing capable of supporting a large load. Control Function features are used to move the steps in the azimuthal direction.

Application Library Title:
step_thrust_bearing_shape_optimization
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Topology Optimization of a Beam with Milling Constraints

The mass of an aluminum beam is minimized through topology optimization subject to a displacement constraint and a distributed load. This previously available model has been modified to demonstrate the use of the new milling constraints with milling from the x- and y-axes.

Application Library Title:
beam_optimization_milling
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Design Optimization of a Beam

The mass of an aluminum beam is minimized through shape optimization subject to a displacement constraint and a distributed load. This previously available model has been updated with new functionality that ensures continuity of the normal vector between the two second-order Bernstein polynomials that define the shape of the lower boundary.

Application Library Title:
beam_optimization
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Maximizing the Eigenfrequency of a Shell

The lowest eigenfrequency of a shell is optimized by deforming its shape using the Polynomial Shell feature. The rightmost boundary is fixed in the Shell interface, while the other external edges are fixed in the Shape Optimization interface.

Application Library Title:
shell_eigenfrequency_shape_optimization
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Topology Optimization of a Sound Partition Considering Acoustic–Structure Interaction

This model reproduces an academic paper on the design of a sound barrier. The mixed formulation of the Solid Mechanics interface is used to set up a topology optimization for the acoustic–structure interaction of the barrier. The resulting design is verified with a body-fitted mesh.

Application Gallery Title:
topology_optimization_solid_aco
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Bracket — Stress Optimization with Fatigue Evaluation

This example demonstrates shape optimization together with a structural fatigue evaluation and minimizes the approximate maximum stress of a bracket. The mass and stiffness are constrained with respect to the initial values. The fatigue life is improved after optimization (bottom), as compared to the initial geometry (top).

Application Library Title:
bracket_fatigue_optimization
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Wheel Rim — Stress Optimization with Fatigue Evaluation

The approximate maximum stress of a wheel is minimized using shape optimization. The full wheel is modeled, with sector symmetry applied. The sector used for stress evaluation uses a finer mesh.

Application Gallery Title:
rim_fatigue_optimization
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Wheel Rim — Topology Optimization with Milling Constraints

A wheel rim model is optimized for stiffness with respect to 12 load cases, using topology optimization with manufacturing constraints. The full wheel is modeled, with sector symmetry imposed for the shape optimization.

Application Gallery Title:
wheel_topology_optimization_milling
Download from the Application Gallery