Written by: Jared Spaniol, Elite Application Engineer
SOLIDWORKS has done a great job of adding more value to the software year over year and SOLIDWORKS 2018 is no exception. SOLIDWORKS 2018 has seen the addition of many great features, but none as powerful as the new Topology Study option in the SOLIDWORKS Simulation Professional and Premium packages. There is software available that only does Topology optimization and nothing else, so having this rolled into SOLIDWORKS is a significant addition.
This new feature allows the user to specify certain goals and constraints such as stiffness to weight ratio, minimize the maximum displacement, and minimize mass with a displacement constraint. The user can also input specific manufacturing controls such as preserved regions, thickness controls, demold directions, and symmetry planes. The software will then calculate an optimized shape to meet the constraints and specifications. The method behind topology optimization is that a large portion of the material in most blocky shaped parts that get designed is under very little stress, so it can be cut away. Topology optimization will basically tell you where to make the cuts and remove material.
Let’s look at an example part and see how a Topology study was used to create a lightweight part that has maintained strength while reducing weight. Figure 1 shows the original design of the part. This is a high end automotive part for a custom car that is used in the hinge assembly for the hood opening mechanism.
To start a new Topology study, select “New Study” from the Simulation command manager and then choose Topology Study (see Figure 2).
Adding constraints and boundary conditions in Topology is essentially the same as setting up a standard simulation study and just as easy. The steps are as follows:
- Apply a material
- Select appropriate fixtures
- Specify the loads
- Select contact sets as needed
The additional steps needed with a topology study include specifying the goals and constraints and the manufacturing controls.
In this example, the following setup was used to optimize the part (See Figure 3). The red highlighted box denotes the additional setup options to control the Topology optimization.
In this example, the goal was to use the mass constraint and reduce the part mass by 75%. The preserved regions that were selected are the three mounting holes on the part. This allows the user to determine areas that are not to be adjusted during the optimization process. These would normally be areas that are for part mounting, specific connection points, or any area of concern.
After running the Topology Simulation, the software will provide a rough shape that can be output in a variety of ways (See Figure 4). One key thing to note with the Topology results is the software does not create this final shape for you. It shows a smoothed mesh that can be exported as a graphics body, a solid body, or a surface body. Then, the user would make the changes to the model to best reflect the new optimized shape.
Once the changes have been made to the model, it is a good practice to re-run a static simulation and compare the relative results with the original design to verify the new part will not fail. Depending on what goals and constraints were selected for the Topology study, you can also compare these inputs to see how close they came with the new design.
Figure 5 shows the final shape that was modeled around the topology optimized result. There are many ways to model this part based on the topology study results that will all have different geometry, but this is just one way that closely represents the results.
The big question is…did the goals and constraints that were specified get accomplished and is the design still within limits or at least comparable to the original?
In this case, the answer is yes. The summary of results chart below shows the results comparison for part weight, stress, and deflection (See Figure 6).
Keep in mind that the main goal was to reduce the part mass by 75% as specified in the optimization study constraints. It’s clear that goal was achieved when looking at the new part mass. This result can be variable because it depends on how the user models the changes to the part, but in this case, it got very close. The stress did increase slightly, but it is still below the yield strength (Al Alloy 6061 Yield Stress = 55.15 MPa). This may be a concern for the Factor of Safety depending on the design inputs, but that can always be easily adjusted with a geometry change based on where the high stresses appear in the part. The deflection did increase significantly, which makes sense based on the amount of material that was removed, but it is still negligible in the grand scheme of the design and should have little effect on function.
That is the general setup and workflow of how the Topology study tool works and what can be gained from using it.
The primary benefit of this study is to get an optimized (in this case, lightweight) part that will still meet or exceed the design inputs and constraints. There are many industries that can benefit from this technology, but aircraft and automotive are two that would be high on the list. I’m sure you can think of many more industries where this can be a great benefit. If this is something you’d like to know more about feel free to reach out to us and find out if this tool is for you.