Topology optimization is an engineering optimization method that can minimize the structure and material needed to safely support a specified set of loads. Most implementations of this method use an iterative approach to refine a model and then present tabular or graphical results. These results can be difficult to interpret, and changing parameters requires recalculation—a repetitive iterative process that can be frustrating and tedious.
A real-time interactive application solves this problem by simplifying the design process and allowing the engineer to immediately see changes in the design. TopOpt is a smartphone or tablet app that uses an interactive touch-screen interface to provide real-time feedback and visualization of design and parameter changes.
The TopOpt app was jointly developed through collaboration between the Mechanical Engineering and Mathematics departments at the Technical University of Denmark. It is available in 2D format for the iPhone, Android, and Windows computers, and a 3D format is available for Windows and the iPhone.
The Android, Linux, and Windows version of the 2D app and the Windows version of the 3D app were used for this review. The app is available in Google Play or the Apple App Store. Download and installation of the Android phone version proceeded without issues, and the application opened and started without error. Download and installation of the Linux version of the app was also uneventful.
The Windows versions of both the 2D and 3D apps did not proceed so smoothly, however. I had difficulty installing both version under both Windows 7 and Windows 10. Helpful installation notes from the vendor suggest updating the Visual C++ libraries as well as the ACML library, but even after following these suggestions, I still had issues with the application. I eventually got the app to run, but closing the app remained problematic.
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Figure 2. Default loads are set at the startup screen. (Android version on the left; Linux version on the right.)
There is a bit of a learning curve to using the app, and the vendor thoughtfully provides both a user manual and tutorials as guides. The app starts with a default load and supports as shown in Figure 2. For the bridge design example tutorial, the load is stretched to form a uniform distributed load, and the supports are moved to the ends of the load, resulting in an arched bridge form.
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Figure 3. Load distribution and supports are moved to model a bridge. (Android version on the left; Linux version on the right.)
This resulting form will support the load but requires an excessive amount of material. To use less material for the same load, the volume fraction can be reduced to 0.20 as shown in Figure 4.
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Figure 4. Reducing the volume fraction to 0.20 reduces material requirements. (Android version on the left; Linux version on the right.)
Reducing the volume fraction reduces the material requirements and causes the app to draw support structures rather than solid structures. At this point, I noted that different versions developed different solutions for the same inputs. As shown in Figure 4, the Android version calculated different vertical supports than the Linux version.
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Figure 5. Moving the load lower in the window adds supports extending to the arch. (Android version on the left; Linux version on the right.)
Moving the load down in the window produces a bridge design with the deck load suspended from the arch as shown in Figure 5. Again, note that the Linux version calculates more supports than the Android version.
TopOpt2D also provides an option to export an STL file for 3D printing. Figure 6 shows a 3D model exported from the Android version of TopOpt2D. The 3D model does not transform the 2D design to a 3D design, but rather stretches the 2D structure to a specified thickness. The resulting 3D-printed model may better represent the design as well as provide a model for testing.
One feature that seems to be missing from the app is an “undo” feature. The ability to reverse the last step would be helpful, particularly when working on a small screen such as a phone. I found the app quite difficult to use on a small phone screen, but found it very usable on a larger tablet screen.
TopOpt is an interesting app that provides a way to quickly check out design ideas and get a reasonable approximation of a design. It is quite useful as a “back of the envelope” calculation tool for initial design and concept evaluation and validation.
For more information, visit the TopOpt2D web page.