Harnessing the power of topology studies in SOLIDWORKS Simulation: Part 2

Topology studies, available in SOLIDWORKS Simulation, are a highly effective way for design engineers to create lightweight, optimized parts. Topology studies can be used to explore a variety of design iterations to satisfy an optimization goal, subject to a set of geometric constraints.

Topology studies start with a maximum design space which represents the maximum allowable size for the component. The topology optimization then seeks a new distribution of material, within the boundaries of the maximum allowable geometry, considering all the external loads, fixtures, and manufacturing constraints.

A variety of optimization goals are available to the user, including best stiffness to weight ratio, minimum mass or minimum displacement of a component.

In Part 1 of this two-part blog we covered the first 5 steps needed to set-up a topology study in SOLIDWORKS Simulation using the example of a simple bracket. This blog will cover the final steps of the process

Step 6: Apply manufacturing controls

Manufacturing controls add additional constraints to assist in maintaining a part that can be manufactured.

Right clicking on the manufacturing controls folder yields the following menu:

The options available are ‘Add Preserved Region’, ‘Specify Thickness Control’, ‘Specify De-mold Direction’ and ‘Specify Symmetry Plane(s)’.

‘Add Preserved Region’ will retain certain regions of the part (for example near bolt holes or fixtures or applied loads). For example, I specified a 5mm ring of material around the bolt holes as a preserved region that must be maintained.

I also specified a 5mm ring of material around the hole for the pin as a preserved region that must be maintained.

‘Specify Thickness Control’ allows the user to limit the minimum thickness of structural members created during the optimization process. It also affects the size of the elements used in the mesh. Too thin a selection will cause a spindly, ‘tree like’ structure with lots of thin branches and very long solution times, so be careful. I chose 5mm as my minimum member thickness.

‘Specify Symmetry Plane’ allows the user to select planes of symmetry in the model. I wanted my finished part to have left-right symmetry, so I chose the ‘Half Symmetry’ option and the Right Plane of my model as the symmetry plane.

The last option available as a manufacturing control is ‘Specify De-mold Direction’. This adds de-mold controls to ensure that the optimized design is manufacturable and can be extracted from a mold. I did not apply this as a constraint on my model.

Step 7: Mesh and Run

Like any simulation study we need to apply a mesh before we can solve. For topology studies the recommendation is to use draft quality elements, with 3 elements through the thickness of the members. This will achieve a good compromise between accuracy and run time. Because I chose a 5mm minimum wall thickness as a thickness control, the recommended draft quality mesh size is about 1.67mm.

With the mesh complete the next step is to hit the run button and then go get a cup of coffee. Topology runs can take a little while!

In this case the solver took about 5 minutes to complete. If you choose a finer mesh or high quality elements, expect run times to increase significantly.

Step 8: Post process the results

Once the solver is done crunching the numbers it is time to review the results.

The most interesting plot available in a topology study is a material mass plot which can be found by right clicking results and then selecting ‘Define New Material Mass Plot’.

This opens a property manager with two sliders. The top slider adjusts the material mass. We can drag the slider to the left to show a heavier part or to the right to display a lighter part. If we click the ‘Default’ button it will display the specific part mass that we targeted in our goal setting.

The second slider adjusts the coarseness or smoothness of the mesh. The mesh consists of tetrahedral elements that have sharp corners, but this slider lets the user ‘knock off’ the sharp corners of the elements to display a more realistic smoothed surface. I recommend moving this slider all the way to the right.

Our optimized bracket part is displayed below. You can see the outline of the original maximum design space as a wireframe line. The optimized shape has taken quite a different, more ‘organic’ form than the baseline design.

Step 9: Prepare the optimized part for manufacturing

The final step in the process is to prepare the optimized part for manufacturing. The optimized part can be exported and inserted into the maximum design space model as a new configuration. Right clicking on the material mass plot in the results folder brings up a menu which allows us to ‘Export Smoothed Mesh’.

Parts like this are excellent candidates for additive manufacturing(aka 3D Printing). If that’s not an option, the next step is to recreate this smoothed shape using the parametric modeling tools available in SOLIDWORKS 3D CAD. Recreating the shape will remove all of the tessellations that are a result of the mesh elements, resulting in smoothed surfaces appropriate for machining or other forms of manufacturing. The CAD modeling steps are beyond the scope of this blog.

Conclusion

Brackets like the one used in this example are often found in applications like high-end racing cars, sailboats and aircraft. In these industries, saving weight is often critical to obtaining superior performance. The optimized shape of the bracket in this example resulted in a mass savings of about 30% relative to the baseline design. Topology studies are an extremely powerful way to create optimized shapes which could give designers and engineers a tangible performance edge.

Now go design some innovative products with the help of the comprehensive analysis tools available in SOLIDWORKS Simulation.

Alon Finkelstein
Simulation Product Specialist
Computer Aided Technology, Inc.