Introduction to Generative Design with Fusion 360
Overview of Generative Design
Generative Design mimics nature’s evolutionary approach to design. Designers or engineers input design goals into generative software, along with parameters such as materials, manufacturing methods, and cost constraints. Unlike topology optimization, the software explores all the possible permutations of a solution, quickly generating design alternatives. It tests and learns from each iteration to ascertain what works and what doesn’t. Generative Product Design breaks down into four components: the function of the part, materials used, the manufacturing process, and how it needs to perform.
The function of the part is a combination of loads and forces that are applied and known physical constraints that restrict the space and mounting points. In traditional design methods, you take the information you know and mix that with traditional shapes to develop a couple of concepts then you run an analysis on each iteration to look for the best performance. With generative design, you build bodies that represent preserved areas, obstacles, and starting shapes. You will apply loads and constraints to these bodies to help define the function of the part.
The material that is used for the part design can vary and has a direct effect on the strength of the part. In a traditional design setting, the material is not necessarily known until the part is created. You start with a single material, then adjust based on the outcome of the analysis. With generative design, you assign multiple materials so that you can optimize your design process.
The manufacturing process of the part is also not always known and can range from machined, cast, fabricated or printed. With traditional design, the manufacturing process is typically determined by the design of the part. With generative design, you select from a list of options to derive results based on the options selected.
At this point, you begin comparing the results to decide what is the best option to use. Traditional design requires that you review the part design, the part analysis, and the manufacturing options to decide which design fits your specific needs. Generative design allows you to compare these options all in one place, then simply download the desired solution that best fits your needs.
This is an example of a common design process used to develop and evaluate a design chosen to be run through a Generative Design software.
- Identify the problem domain and gather information: Spend some time thinking about the problem at hand and how it fits into the greater context of your operation. Ask yourself: How does the new part(s) interact with the greater assembly? What kind of manufacturing, assembly, or other practical considerations is present? Are there any dynamics at play (e.g. moving parts, changing loads, etc.,)? What is my end goal - is it weight/material reduction, performance enhancement, aesthetics, or some other metric improvement?
- Create preserve geometry: Start with the existing base model, be it a single part or a full assembly. Create the interface geometry (e.g. bolt bosses, flanges, etc.,) as new bodies to be used by the generative process. Be sure to include any needed extra grind/machine stock, fluid containment walls, or other "oddball" preserves.
- Create obstacle geometry: Again, working with the base model, create any obstacle geometry needed. This might include fasteners (nuts, bolts, screws, pins, etc.,). It also might include more complicated geometry like swept solids (e.g. the path a toggle clamp makes as it swings into position). Be sure to include any needed tool clearances (wrench or ratchet). One "gotcha" to keep in mind: people often create obstacles that are too short - make sure your obstacles clear the envelope of the problem setup.
- Set up your boundary conditions: Specify the constraints, loads, manufacturing details, and materials into the system. Be sure to build your load cases based on any dynamic motions that may be involved (for example, a part of a car suspension may experience braking, acceleration, turning, or stasis).
- Run your studies: At this point, run your various studies. Pay attention to early results to ensure that you're getting the expected kinds of solutions. You'll notice fairly early on if an obstacle is too short or if you've forgotten some specific detail.
- Examine your results:As your results are delivered, use the tools available to determine which solutions are worth further investigation. This may be a combination of using scatter plots, visually comparing possible solution results, or inspecting the model stress visualizations.
- Compare results to initial expectations: Circle back to step one and validate what results were generated against what you expected or desired. You may discover that a result didn't quite make it to the end and needs to be pushed through as a starting shape to further refine it. Maybe you have an intriguing result that would make a great starting shape for a secondary study. Perhaps you've identified some results that you would like to validate with an additional FEA package.
- Integrate back into the base: Once you've generated a result that you're satisfied with, export it as a BRep/TSpline and place it back into the base model to inspect the context again. Begin thinking about next steps with regards to CAM, 3D printing, CAE validation, etc. Add in required features like machining operations or modify the TSpline as needed to achieve your contextual requirements.
- Take next steps: Take your final model out to CAM, CAE, 3D printing software, or whatever the next stage is for your design.
- Rinse and repeat: Continue working through this process iteratively to further refine your designs.
Fusion 360’s Generative Design is utilized in many areas of design - from Architecture through Manufacturing. If you would like more information on Generative Design and will be attending Autodesk University this November 2019, we recommend these courses:
I would like to thank Kenny Cornett for his input and feedback on the content of this document.