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NOWLAB dove into designing the airless tire's internal structure by considering biomimicry engineering. A strategy in many NOWLAB projects, biomimicry makes use of functional designs found in nature to create similar properties in human-designed products. In the case of NERA’s tires, a honeycomb design was chosen to provide the tire internal stability for its efficiency in balancing the required rigidity and flexibility. The geometry proved strong enough to take full advantage of a flexible material, BigRep’s TPU filament, which has proven capable of keeping shape under weight with the chosen geometry but maintains its properties well enough to mimic the soft function of a traditional tire.

After choosing the honeycomb pattern that would be the design’s basis, the team needed to ensure the product’s overall properties would meet their needs. Mirek Claßen, NOWLAB Head of Innovation and Generative Design Applications, helped apply algorithm-based parametric design to ensure the tire would meet its requirements for the specific customized range of weight-resistance and size that was needed for its function on the NERA, a process that also ensures the airless tire is easily adaptable for future applications with different functional requirements.

“Combining the possibilities of generative and parametric design allowed us to unlock the full potential of large-format 3D printing,” said Claßen. “Within our algorithm-based design model we could iterate unlimited design variations to find the perfect version to suit our needs and fulfill all technical requirements.”

Both the NERA’s airless tires and rims are fully 3D printed, demonstrating the functional and impressive ability of BigRep’s TPU and Pro HT materials to withstand a vehicle and driver’s weight. BigRep’s NERA was designed to hold passengers over 110 kilograms, but the design can be altered to support even more weight for heavier vehicles or heavier loads like multiple passengers.

Pro HT was an apt choice for the NERA’s rims for the same reason TPU was suited for the tire – it has the perfect balance of rigidity and flexibility for its application. Overall the rims require far more rigidity than the rubber-like tires, of course, but striking a balance ensures the rims remains solid and sturdy but aren’t so brittle as to crack under weight. The material’s marginal flexibility also adds an amount of shock absorption to the wheels, making for a smoother ride.

Beyond the airless tires, BigRep’s materials like TPU allowed for embedded functionalities in a unique way. The NERA’s bumper, seat and handles were all printed with TPU to fulfill functions that usually require complex mechanical constructions like hydraulic suspension systems.