Topology Optimization Using SolidWorks Simulation

A Topology study performs nonparametric topology optimization of parts. Starting with a maximum design space (which represents the maximum allowed size for a component) and considering all applied loads, fixtures, and manufacturing constraints, the topology optimization seeks a new material layout, simplifies structural topology investigations with a goal-driven approach to mathematically alter the stiffness of the meshed geometry.  Assuming linear static loading designers and engineers specify target mass reduction and the delivered results show which regions of a component can be removed within the boundaries of the maximum allowed geometry without compromising the component stiffness, by redistributing the material with all the required mechanical and manufacturing requirements satisfied.

The SOLIDWORKS Simulation Topology Study included in the SOLIDWORKS Simulation Professional version

Consider the below Example wherein we can optimize the part of a car hood opening mechanism, as shown in the image below in blue, in terms of strength and weight (image courtesy of Ring Brothers LLC).

With a Topology study, we can define a design goal stating

• Best stiffness to weight ratio
• Minimize the mass
• Reduce the maximum displacement of a component.
• Enforce manufacturing constraints

Thereby making the design proposal reached by the iterative optimization process should fulfill all structural and manufacturing requirements predefined.

By carrying out a motion analysis on the assembly, the loads at the link connection points can be calculated and transferred to the part for analysis. The loads on the blue link are shown by the size of the yellow arrows in the image below and the maximum load on the gas strut.

It is always best suggested to complete a static analysis to the part prior to running a topology study to ensure that the loads applied do not result in stresses that are beyond the components yield strength.

Creating a Topology Study is pretty much similar a static study; the materials, loads and restraints are the same.

The difference is the only 2 new inputs:

• Goals and Constraints.
• Manufacturing Controls.

Goals and Constraints

In a Topology study tree, right-click Goals and Constraints, and select one of the three optimization goals:

• Best Stiffness to Weight Ratio,
• Minimize Mass
• Minimize Maximum Displacement

Best Stiffness to Weight ratio (default)

• The optimization algorithm yields the shape of a components with the largest stiffness considering the given amount of mass that will be removed from the initial maximum design space.
• When you select Best Stiffness to Weight ratio, the algorithm seeks to minimize the global compliance of the model which is a measure of the overall flexibility (reciprocal of stiffness). Compliance is defined by the sum of strain energies of all elements.

Minimize Maximum Displacement

• The optimization algorithm yields a shape that minimizes the maximum displacement on a single node (derived from a static study).
• With a given percentage of material to remove from a component, optimization yields the stiffest design that weighs less than the initial design and minimizes the maximum observed displacement.

Minimize Mass with Displacement Constraint

• The optimization algorithm yields a shape that weighs less than the maximum size model and does not violate the given target for the displacement constraint.
• The algorithm seeks to reduce the mass of a component while restricting the displacement (max observed value of component or user-defined at a single node) under a certain limit

Constraints

Constraints limit the design space solutions by enforcing the percentage of mass that can be eliminated to be under a certain value,

Mass constraint

;

Set the targeted mass that the part will be reduced by during optimization. Select one of the following:

• Reduce mass by (percentage): Type the targeted percentage of mass reduction
• Reduce mass by (absolute value): Type the exact value of the mass to remove from the part’s maximum design space.

The optimization algorithm will attempt to reach the targeted mass reduction for the final shape through an iterative process.

Displacement constraint

Sets the upper limit for the selected displacement component. In Component, select the desired displacement variable. Select one of the following:

• Specified value: Type the targeted value for the selected displacement variable, and set the desired units in Units.
• Specified factor: Type a factor to multiply the maximum displacement calculated from a static study.

Select one of the following for a reference vertex location for the displacement constraint:

• Automatic (single max point): The program selects by default the vertex of the maximum displacement observed in the model.
• User defined: Select in the graphics area the reference vertex for the displacement constraint

Manufacturing Controls.

The optimization process creates a material layout that satisfies the optimization goal and any geometric constraints you define. However, the design may be impossible to create using standard manufacturing techniques, such as casting and forging.

Applying proper geometric controls prevents the formation of undercuts and hollow parts. Manufacturing restrictions ensure that the optimized shape can be extracted from a mold, or can be stampable with a tool and die.

Preserved Region Property Manager:

We can freeze regions of your model that are contacting other parts, such as regions that are used to support the model and regions that form bearing surfaces. These regions do not participate in a topology optimization and remain unchanged.

De-mold Control:

We can add de-mold controls to ensure that the optimized design is manufacturable and can be extracted from a mold. Application of geometric controls prevents the formation of undercuts and cavities and ensures that the optimized shape can be extracted from a mold.

The below are the 3 possibilities in specifying the directions

• Mid-plane (both directions)
• Pull direction only
• Stamping (pull direction only)

Symmetry Control:

Symmetry control forces the optimized design to be symmetric about a specified plane. You can enforce a half, quarter, or one-eighth planar symmetry for an optimized design.

• Specify one plane for Half Symmetry,
• two orthogonal planes for Quarter Symmetry, and
• three orthogonal planes for One-eighth Symmetry

Thickness Control:

Apply member size restrictions for a topology optimization that prohibits the creation of very thin or very thick regions that may be difficult to manufacture. The final optimized design adheres to the member size restrictions you specify.

Results

Once you have your topology results

• SolidWorks Topology optimization proposes the best optimized geometry out the goals & constrains and Manufacturing Controls we have given.
• the result from a topology study can be exported as a smoothened mesh. This mesh can be sent directly to a 3D printer for manufacturing, but further validation of your component based upon the printer’s materials is essential.

• The results from a topology study can be overlaid onto the original geometry and used as a guide to create cut-outs and pockets for traditional CAM solutions.

Optimization proposal for SolidWorks Topology Optimization

Optimized Geometry

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