Modern fabrication tools, such as 3D printers, can fabricate structural materials in ways that would have been difficult or impossible with conventional tools. Meanwhile, new generative design systems can take advantage of this flexibility to create innovative designs for parts of a new building, car, or virtually any other device.
But such automated “black box” systems often fail to produce designs that are fully optimized for their purpose, such as providing the greatest strength-to-weight ratio or minimizing the amount of material needed to support a given load. Completely manual design, on the other hand, is time and labor intensive.
Now, MIT researchers have found a way to get the best of both approaches. They used an automated design system, but stopped the process periodically to allow human engineers to assess the work in progress and make modifications or adjustments before allowing the computer to resume its design process. Introducing a few of these iterations produced results that performed better than those designed using the automated system alone, and the process was completed more quickly compared to the fully manual approach.
The results are reported this week in the journal Structural and Multidisciplinary Optimizationin a paper by MIT doctoral student Dat Ha and assistant professor of civil and environmental engineering Josephine Carstensen.
The basic approach can be applied to a wide range of scales and applications, Carstensen explains, for the design of everything from biomedical devices to nanoscale materials and structural support members of a skyscraper. Automated design systems have already found many applications. “If we can do things in a better way, if we can do what we want, why not do it better?” she asks.
“It’s a way to take advantage of the way we can do things in much more complex ways than in the past,” Ha says, adding that automated design systems have already come into wide use over the past decade in the automotive and automotive industries. aerospace. , where reducing weight while maintaining structural strength is a key need.
“A lot of weight can be taken off of components, and in these two industries, it’s all about weight,” he says. In some cases, such as internal components that are not visible, appearance is irrelevant, but for other structures, aesthetics may also be important. The new system makes it possible to optimize designs in both visual and mechanical properties, and in such decisions the human touch is essential.
As a demonstration of their process in action, the researchers designed a series of structural load-bearing beams, like those that might be used in a building or bridge. In their iterations, they saw that the design had an area that could fail prematurely, so they selected that feature and requested that the program address it. The computer system then revised the design accordingly, removing the highlighted strut and strengthening a few other struts to compensate, leading to an improved final design.
The process, which they call Human-Informed Topology Optimization, begins by establishing the necessary specifications; For example, a beam must be this long, supported at two points at its ends, and must support this load. “As we watch the structure evolve on the computer screen in response to the initial specification,” says Carstensen, “we interrupt the design and ask the user to judge it. The user can select, say, ‘I’m not a fan of this region, I’d like you to increase or decrease this feature size requirement.’ And then the algorithm takes user input into account.”
While the result is not as ideal as what a fully rigorous but significantly slower layout algorithm considering the underlying physics could produce, he says it can be much better than a result generated by just a fast automated layout system. “You don’t get something that great, but that wasn’t necessarily the goal. What we can show is that instead of spending several hours to get something, we can spend 10 minutes and get something much better than what we started with.”
The system can be used to optimize a design based on desired properties, not just strength and weight. For example, it can be used to minimize fracturing or buckling, or to reduce stresses in the material by smoothing out corners.
Carstensen says: “We are not looking to replace the seven-hour solution. If you have all the time and all the resources in the world, you can obviously run it and it will give you the best solution.” But for many situations, such as designing spare parts for equipment in a war zone or disaster relief area with limited computing power available, “then this type of solution that directly addresses your needs would prevail.”
Similarly, for smaller companies that build teams into quintessentially “mom and pop” businesses, such a simplified system might be just the ticket. The new system they developed is not only simple and efficient to run on smaller computers, but also requires much less training to produce useful results, Carstensen says. A basic two-dimensional version of the software, suitable for designing basic beams and structural parts, is freely available. now onlinehe says, as the team continues to develop a full 3D version.
“The potential applications of Professor Carstensen’s research and tools are quite extraordinary,” says Christian Málaga-Chuquitaype, professor of civil and environmental engineering at Imperial College London, who was not involved in this work. “With this work, his group is paving the way toward truly synergistic human-machine design interaction.”
“By integrating engineering ‘intuition’ (or engineering ‘judgment’) into a rigorous but computationally efficient topology optimization process, the human engineer is given the ability to guide the creation of optimal structural configurations in a way that was not available to us before,” he adds. “Their findings have the potential to change the way engineers approach ‘everyday’ design tasks.”
