An efficient tire must meet multiple objectives, including fuel consumption, durability, shock and cut resistance, rolling noise, grip on dry or wet roads, aquaplaning prevention… Many of these constraints involve complex physics and, for the most part, entail contradictory compromises.
Nextflow Software, one of our partner, has been working for years with Michelin to improve their tires. Recently, Julien Bergounhoux, French journalist at “L’Usine Digitale” interviewed Yohan Le Chenadec, Research Team Manager of Michelin, and Vincent Perrier, CEO of Nextflow Software, to know more about their simulations. The full paper in French.
“To create the best possible products in a highly competitive environment, we need to integrate the last innovations as far as tire material, tread and architecture are concerned. The only way to do it efficiently, by testing and improving tire during the design phase, is by using numerical simulation.”Yohan Le Chenadec
Among the numerous design constraints, aquaplaning directly involves fluid structure interaction. Understanding the actual dynamics is not easy. Indeed, the flow beneath the tire and inside its grooves cannot simply be observed or measured, with good reproducibility and reliability. Even if it could, such experiments for designing new tires would imply expensive prototypes and on-track testing facilities. Such financial and time constraints would prevent designers from assessing numerous innovative concepts.
SPH-Flow allows us to avoid a hard and complicated step required by classical methods: the fluid-structure mesh. It is usually needed to define in details the 3D environment in which the simulation is done, namely the fluid volume. Unfortunately, a method with mesh does not allow the simulation of a complex environment like a tire changing shape and moving into a given water volume.Vincent Perrier
By coupling the Michelin solid tire model with the Nextflow fluid model taking in charge of the road water interaction, it is possible to obtain a simulation in only one hour rather than a week with a mesh. It is now possible to simulate more complex problems, for example, the roughness of the small stones on the road, finer groove depths..
Michelin is able to produce tires with longer lifespan with those methods. As far as hydroplanage is concerned, the vacuum volume, used to stock and evacuate the water, is decreasing with wear. To remain performant, some hidden cavities and furrows would appear during the tire life to keep the same evacuation capability. This innovation is already available on the market.
Of course, Michelin is still realizing physical prototypes to validate simulation before going to production. However, this numerical approach allows more testing, better and upstream to only create prototypes in the final design phases.
It means saving time and money.