Think about being tasked with designing a chair. How would you go about it? Would you start off with a few rough sketches of general designs before choosing one to focus on? How many designs can you think of and consider? Maybe two or five or even 10? Once there’s a batch to work with, it would be time to do the calculations and considerations, to eliminate design candidates that might not support the required weight, or perhaps not provide the necessary surface area.
But what if instead of taking these steps to come up with a few designs, you could have thousands of designs to choose from—all of which fit your stated parameters? This would expose possibilities that you might never have imagined.
This is where generative design comes in. Think of it as "another brain in the design studio"1— a computer program that uses algorithms to explore and populate the design space. As shown in the image below, you might end up with something fairly standard, or your chair may end up looking like something straight out of the Museum of Modern Art, while meeting all of your design requirements.
Figure 1: Autodesk Dreamcatcher example designs for a chair.2
A closer look at vendors and products
The big player in this field is Autodesk, with the Project Dreamcatcher product capturing the goals and constraints defined via a well-stated problem from the imagination of the designer. Dreamcatcher takes over defining the points, lines and surfaces of the design, which frees up the designer to truly embrace their creativity and concentrate on thinking about the goals, the design tradeoffs and the look and feel of the design. This process ends up being a dialogue between the designer and the program. Dreamcatcher generates a number of designs, and the designer explores the output, adjusts the constraints to guide the program, and repeats the process until satisfied with the final outcome.
Figure 2: Autodesk Project Dreamcatcher offers a reimagined design flow.3
Another generative design solution in the field is solidThinking with two products—Inspire (Figure 3) and Evolve4, which use human bone growth—inspired algorithms to create an optimized design as defined by the designer and then abiding (or exceeding) the design constraints. Unlike Project Dreamcatcher, only one design is created in this case.
The design framework is first generated in solidThinking Inspire, which produces a general optimal design shape. The designer then has a choice to either use the generated structure as a guide for a finished design, or to port it to solidThinking Evolve and allow the algorithms and tools provided through the software to finalize the design. Several companies have used this generative design to improve the properties of their designs, such as how RUAG used it to improve the antenna bracket for Sentinel-1 Satellite, as shown in Figure 4.
Figure 3: solidThinking Inspire design generation flow.5
Figure 4: Antenna bracket, redesigned using solidThinking Inspire.6
How generative design works
The generative design process starts with a designer defining a bounding/design area, connection points and obstacles, as well as a variety of constraining parameters. An example of the first three can be seen in Figures 5, 6 and 7, where these parameters are defined for a motorcycle swingarm design.Optimization is based on desired materials, manufacturing technologies (method of production), temperature tolerance, cost, and strength of the part and its ability to withstand specified forces.
Normally, a designer would have to spend several hours trying to calculate whether their proposed design would fit these constraints. In contrast, this is done by default using generative design and all of the resulting designs will fit the defined constraints, and often exceed them. Because of this effective automation of tasks through software, there is room for the designer to play around with aesthetics of the part and invest more time into exploring creative and effective designs.
Optimizing through constraints
So, what about all of these constraints? You might not care about parameters like temperature, flex or weight to a great extent for a chair. But you would for brackets, winglets or gas turbines in planes, or bridges that you walk and drive over. When airplanes fly, for example, every ounce of weight translates into huge incurred fuel costs. Parts must be able to withstand tremendous forces and large variations in temperature, with proper heat dissipation.
Manufacturers are always trying to optimize their parts to account for weight and harsh conditions. General Electric, in partnership with GrabCAD, went so far as to launch a 3D Printing Design Quest. They challenged the public to redesign a metal jet engine bracket, making it 30 percent lighter while preserving its integrity and mechanical properties like stiffness.8 The winning design sheared off 84 percent of the weight of the original bracket, taking the total weight from 4.48 pounds to just .72 pounds (Figures 9, 10).
Using generative design, companies could duplicate this crowdsourcing effort internally, using the software program algorithms to arrive at numerous solutions that fit desired parameters.
Fig.9: GE’s redesigned jet engine bracket.8
Generative design and 3D printing
Using additive manufacturing (3D printing) allows for even more design possibilities. This can be done by varying the parameter of “manufacturing technology” in Dreamcatcher. Additive manufacturing technology has been evolving at a rapid pace. It is now to the point of producing parts of industrial quality due to the likes of FIT AG9 for metals and Carbon3D10 for polymeric plastics.
Autodesk also offers a generative software product called Within11, which makes use of additive manufacturing capabilities to create lightweight, latticed designs for automotive, medical implant, aerospace and industrial equipment applications. These designs would not be producible by traditional means. Using Within, engineers were able to create a lightweight, load-bearing engine block that had better heat dissipation and superior performance (Figure 11); a lightweight roll hoop for Formula One racing cars (Figure 12); a customized implant for cranioplasty (Figure 13), and micron-accurate rough lattice surfaces for medical implants to aid fixation with bone.
Figure 11 - Automotive: Load-bearing engine block.12
Figure 12 - Automotive: Lightweight roll hoop.12
Figure 13 - Medical: Customized implant for cranioplasty.12
Additive manufacturing combined with the Within software has been even more helpful when it comes to traditional injection molding. Figure 14 shows the traditional solid mold on the left side, and a re-designed latticed mold on the right, with better simulated heat dissipation properties. In addition, this mold is more lightweight and requires much less material to produce.
Figure 14: Injection mold optimization using Autodesk Within.13
With the technology constantly evolving and reshaping itself (pun fully intended), the number of design possibilities will explode and manufacturing efficiency will further improve. Think lighter, faster planes with optimal engine heat dissipation. Self-building and self-repairing bridges that look organic and last longer.14 Faster bone growth thanks to biodegradable, bone growth-stimulating optimized and 3D printed implants. And this is just the beginning.