Lightning Motorcycles Revisits Generative Design for Mass Production | Autodesk University

Lightning Motorcycles Revisits Generative Design for Mass Production

Lightning Motorcycles has been breaking records in the world of e-bikes since the company entered the market. The LS-218 is pushing electric and gasoline-powered motorcycles to be the fastest production bike on the market. But pure performance is not the only goal; Lightning is focused on providing consumers with the best quality and value in every product it creates. Key to meeting these goals and staying ahead of the competition are new technology and ways of thinking.

Lightning Motorcycles was an early adopter of generative design. Collaboratively, we produced a part-consolidation and lightweighting workflow that saved 30% of target component mass. In this article, we’ll show you how developments within generative design can be used to gain these benefits, while ensuring cost-effective manufacturing. We'll cover workflows used within Fusion 360, maximizing the integrated simulation, generative design, and manufacturing tools to better understand the part and its performance.

Fusion 360 Generative Design

Fusion 360 Generative Design is a design exploration tool, aiming to cut down the necessary steps within the standard design exploration cycle. It is problem-focused, with real-world loading and geometry inputs driving the design iterations, and allows multiple viable designs to be created simultaneously. Figure 1 shows the standard design-to-production workflow, in comparison with the generative design workflow.

Figure 1. Differences in design exploration workflow.

Key Learning

Generative Design Advancements

One perceived shortcoming of generative design in years gone by is that it creates excessively complex geometry. Our initial work with Lightning Motorcycles shows a good example of this. The software at the time was very new, yet still incredibly powerful. It allowed all these complex geometries to be created yet there was a lot of refinement needed for the workflow to succeed from the very early outcomes.

Figure 2. Initial Lightning Motorcycles generative design outcome.

Figure 2 shows this initial work with Lightning Motorcycles. You can see that the part has a high level of detail, and the original assembly was solved as one part. This was down to the limitations of the software at the time. As a result, the loading would be approximated. Nowadays, we have more complex solvers and a greater variety of load case attributes that we can fully use to better represent the real-world loading.

The other shortcoming of generative design at the time was the fact that it was strongly focused on additive manufacturing. Within generative design, you can now include 2.5, 3, or 5-axis milling, 2-axis cutting and die casting, along with the traditional additive and unrestricted manufacturing methods.

Generative Design Setup

For any problem-based solution to succeed, you need to be able to accurately represent the problem in order to make sure all outcomes are matching the real-world conditions that the part is going to be under.

Figure 3. Rider's left generative design geometry.

For both of the side components, the setup was very similar. Figure 4 shows the geometry used in the setup on the rider's left-hand side part.

Figure 4. Rider's left generative design setup.

Figure 4 shows the actual setup of the generative design. To represent the part as a subset of the assembly, we fixed certain geometries that were not loaded to represent the fixturing to the other assembly parts.

Figure 5. Central component generative design geometry.

The loading of the central component was dictated by a combination of the forces on either side relating to the forces of the side components, and the reaction force from the shock absorber.

Figure 6. Central component generative design setup.

Generative Design Trade-Offs

As is the case with any design process, generative design is full of trade-offs. For the most part, these are trade-offs of performance (mass, factor of safety, displacements) against ease/cost of manufacture. Figure 7 illustrates how this trade-off was performed in a simple yet effective matrix.

Figure 7. Performance comparison.

Fusion 360 Simulation

Fusion 360 Simulation is a validation tool to help you understand how a design performs under certain conditions. A highly trained specialist could spend much time performing a detailed analysis to obtain the exact results of real-world conditions.

Key Learning

Simulation Selection

Static stress analyses are one of the most common types of finite element structural analyses. The component or assembly is subjected to a range of load conditions and the resultant stress, strain, and deformation results are analyzed to determine the likelihood of failure of the design.