Silicon Valley-based AREVO, which develops technology to enable direct digital additive manufacturing of composite parts, has generated excitement with the design and production of an all-terrain city bike – the world’s first bike using a 3D-printed carbon fiber frame. The bike was the first application of AREVO’s 3D printing technology, leveraging a thermoplastic composite filament with continuous carbon fiber from Hexcel, the company’s proprietary Pathfinder software and robotics. According to the company, the thermoplastic filament is five times stronger than titanium and one-third its weight. The company completed the bike frame with only two prototypes.
AREVO’s technology aims for a more efficient and less expensive manufacturing process by integrating software early in the design to reduce the need for physical prototyping. The software allows designers to develop a digital prototype of the product prior to beginning actual manufacturing, making the process more efficient and more sustainable than traditional 3D manufacturing, according to the company.
“When you talk to a rider, how the bike feels – that is the hardness or softness of the bike – and how much it flexes under load is critical. We were able to model the desired riding quality in our Pathfinder software,” says Jim Miller, CEO of AREVO. “The software predicts the behavior and performance before the printing process begins.”
Pathfinder iterates the design based on performance parameters for tensile strength, compression, flex, shear, impact resistance and residual stress (warpage). It determines where the carbon fiber filaments need to be placed to attain the required strength without overdesigning the bike frame. A built-in patented additive finite element analysis (A-FEA) algorithm helps ensure the design meets performance specifications. If the design misses a parameter, the software adds and subtracts virtual material, reiterating the design until specifications are reached while minimizing the use of costly material.
Although the software won’t select materials, it can compare part performance based on material combinations. “We can program Pathfinder to compare the performance of a 50/50 PEEK and carbon fiber tow to the same part in aluminum or titanium, and it will indicate the trade-offs,” Miller says.
In any design environment, part changes are a way of life, and the ability to update and test designs quickly is a benefit. After AREVO manufactured the first 3D bike, it was approached by the German company OECHSLER, which wanted to pair its DRIVEMATIC three-speed automatic gearbox with AREVO’s 3D printed carbon fiber frame for an electric bike. It took one month to move the bike from concept to production, including two weeks for design and one week for printing.