Making Impossible Street Furniture Possible With Generative Design

Lee Sanders
by Lee Sanders 2 months ago 6 min read
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A park bench made to demonstrate the everyday use of generative design to a wider audience.

When you see it, you stop; it looks so familiar but starkly different. Straight-lined wooden slats squarely frame those formless tendrils, a metallic exoskeleton supporting this quite arresting object. It’s a public bench, but like none you have ever seen. The cedar wood’s warm symmetry contrasts with the other-world geometry of the “legs,” merged into an organic tree-like structure beyond human design.

The asymmetrical frame looks wrong at first. Will it take my weight if I sit at one end? As you study it further, and you begin to feel how it all works.

This eye-catching street bench was designed using generative design, a technology that defies convention and makes the impossible possible. Product designer Mark Chester was a masters’ student at Manchester Metropolitan University Print-City when he designed this bench. He was studying industrial digitalization and had 3-4 years’ experience with using Autodesk Fusion 360 when he became immersed in its’ generative design capabilities. 

Generative design is a design exploration process that allows designers to input their design goals and parameters such as performance, spatial requirements, materials, manufacturing methods, and cost constraints into the software. The powerful program explores all possible permutations of a solution, quickly generating multiple alternative designs.

Generative design technology tests and learns what works and what doesn’t from each iteration. In the end, the algorithm presents results that meet the defined criteria to the human designer, who then uses high-level goals and tradeoffs to select the design that best meets their needs.

Though largely unknown to the world, Chester knew that generative design had tremendous potential in product design and engineering. It can create designs that inspire and connect people to products more deeply. He wanted to make something to demonstrate the power of generative design to a wider audience — an everyday object with a design that’s rarely challenged and that people could quickly relate with.

Chester asked himself, “if I was a consumer and I saw a generative design for the first time, how could I best translate what it does, while also having the form of something commonplace?” He chose the common park bench. 

A Fully Immersive Collaboration Tool

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Generative design and the power of the cloud made the asymmetric frame design possible.

Fusion 360 was the go-to design platform to bring this bench to life. Chester knows it intimately, and it’s intuitive, powerful, and fast. Generative design creates hundreds of optimized design variations in minutes, often organic in style, resembling the structures of insects or plants due to the evolutionary algorithms the software is based on. Fusion 360 and generative design have been developed to be, above all, collaborative tools. As a talented product designer but not an engineer, he enlisted the help of engineers at the Autodesk Technology Center in Birmingham and Aristo-Cast, a specialist casting company and Autodesk partner in Michigan, US.

Complex product designs typically have several tens, even hundreds, of people involved, with different levels of experience and geographically dispersed. Effective collaboration has often been the bottleneck of many design projects.

“Typically, in a large design team, the combinations of software tools used can be numerous. You have to fight with the tools, the UI, the feel, the support, and the designers’ varying experience,” says Kelvin Hamilton, Technical Consultant Manager at Autodesk. “What if you could get rid of all that mess and design efficiently? That’s where Fusion 360 comes in.”

The generative design workflow allows you to specify high-level input and constraints of the product including materials, size, cost, weight, stiffness, and volume. Fusion 360 computes different forms of designs that can be made from different manufacturing processes: sand casting, investment casting, injection molding, CNC machining, welding, and additive manufacturing

It creates manufacturable designs that meet the defined constraints. By harnessing the power of the cloud, the software calculates all this for you; change one input parameter or objective and new designs that meet those criteria are computed, giving you infinite permutations to achieve the design you want to fit your constraints. “After you have selected the design you want, you can then continue with subsequent steps such as design review, documentation, validation, and manufacturing – all within the same product innovation platform,” says Hamilton.

Design teams can communicate with each other and external stakeholders in real-time for sharing design and marking-up changes live from a central location. This is fully immersive collaboration. 

Generative Design for Additive and Investment Casting

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Investment cast generative design bench from 356 aluminum by Aristo-Cast.

For the bench, with Fusion 360’s algorithms steering them, Chester and Hamilton chose investment casting as the manufacturing method. For the casting, they selected long-time Autodesk partner Aristo-Cast, who have prior experience of approaching 30 Autodesk casting projects – many using Fusion 360 – including a 3D-printed bionic partition for Airbus and a customized wheel cover and steering wheel for Volkswagen

At 2000 x 1070 x 563mm and 150kg, the bench was too big to form in a single cast. With Hamilton on hand, Aristo-Cast sectioned the design into six separate pieces, exchanging models to confirm the best splitting lines. “We created a 3D puzzle, where each piece could insert into the next seamlessly, so when it was welded there would be no problems with alignment,” says Paul Leonard, VP at Aristo-Cast.

Investment casting uses a pattern to form and support the cast, normally made from wax. The bench pieces were too big for wax, so they used a Voxeljet 1000 3D printer to print sprues and gatings. When the pattern is built, it goes through several dips in a slurry of silica sand, building up a hard ceramic shell outside the pattern. “Once the pattern is dried and cured, it takes one week to get through the dipping room. Then it’s flash-fired and removed from the shell,” Paul says.

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“We blow out the form, remove any residue, and prep it for casting: bake it for two hours in the oven at the correct shell temperature for curing, place it in the sandpit and pour the metal in.” With Fusion 360’s structural simulation help, the team chose 356 aluminum for the cast for its strength and pouring properties. Once cooled, the ceramic, the gating, and the sprue is cut away. Post-process grinding smooths and finishes the product. The bench frame was tack welded into two pieces for shipping to the UK. Once in the UK, the Birmingham Technology Center team worked with the local fabricator, PF Fabrications, to properly weld the bench frame, apply an attractive coat of protective paint and get the bench ready for final assembly with the solid pieces of oak slats — all of which sit on top of the concrete base structure. 

Growing Demand for Nature-Mimicking Structures

Hamilton and Paul communicated constantly throughout the process. Staring at the photos of the bench newly installed at the Autodesk Technology Center in Birmingham UK, Chester glows with pride. “This is the first time I’ve seen it installed, and it’s amazing. I am so delighted.”

His vision is to bring more generative design products to street furniture and to construction more widely, but he wants to enjoy the bench for now and get feedback from first-time users. Paul sees growing demand for these futuristic and nature-mimicking generative design structures in decorative architecture as well as other applications. “Contractors will hire designers in-house to do more of this generative design work themselves. The bench is a great demonstrator, but it’s really just the beginning.” 

Whether you’re designing furniture, transportation solutions, or even small parts, generative design could be a great addition to your workflow. It creates lightweight parts with an organic aesthetic that often saves time, materials, and costs during the manufacturing process. If you’re interested in trying out generative design for yourself, download Fusion 360 today.

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