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Amongst the software Lightning was deploying was Autodesk's much talked about generative design technology, now available as a feature within Autodesk Fusion 360 and Autodesk Netfabb. Generative design tools allow users to explore a multitude of design solutions based on goals and constraints, unlike optimization software which only allows refinement of a known design.
Lightning Motorcycles engineers teamed up with Autodesk research scientist Andreas Bastian to optimize the motorcycle's swingarm.
Lightning had previously attempted to lightweight the bike's swingarm using composite 3D printing technologies, and although the designs worked in theory, the material properties were unlikely to withstand the forces required when riding such a powerful machine.
"We have looked at the swing arm because it is a nice scale of a problem," Andreas said. "It is traditionally made of three parts bolted together, it is made of known materials using known manufacturing processes, and it was developed by engineers, who know a ton about motorcycling."
Previous generatively designed projects had clear goals in that they needed to be both lightweight and structurally sound. However, the swing arm required both those quantitative goals as well as one more qualitative one; maintaining the allusive 'ride feel,' that is crucial to experienced riders.
It was determined using the simulation tools in Autodesk Generative Design that there were five primary load cases, and to sustain ‘ride feel’ the swingarm needed to match as many of these as possible, while at the same time reducing weight.
"What's interesting is you want a different amount of stiffness for different behaviors," states Bastian. "You need high stiffness for normal operating mode because if you are riding and hit a speed bump and your swingarm is floppy, then you will momentarily lose contact with the road and therefore bike. Whereas under race conditions when banking at angles of up to 50 degrees vertical you need a more deflection."
By cutting the weight of the bike without compromising performance, Lightning is now aiming to make the LS-218 even faster by deploying new generative design methods, additive and a manufacturing process that has been around for hundreds if not thousands of years, casting.
The generatively designed swingarm matched its original counterpart in four of the five load cases, with the fifth outperforming by as much as 55%.