YOKOHAMA's Technology
Yokohama Rubber's proprietary "neo-FIALA" analytical model Using mathematical formulas to explain the mechanism behind a tire’s performance
Basic Technology
Tires are essential components that enable cars to run, stop and turn with minimal contact with the road surface. Tires are exposed to various forces that cause slight changes in their shape. These shape changes, or deformations, are a key element affecting tire performance. However, it is extremely difficult to track and measure these changes in tire shape while driving. Yokohama Rubber therefore has developed and is promoting the use of a proprietary "neo-FIALA" (*) analytical model, which uses mathematical formulas to describe the relationship between the dynamics of a rotating tire and tire performance.
*The “neo-FIALA” model is named after the Vienna-born automotive engineer Dr. Ernst Fiala, who worked in the R&D departments at Daimler-Benz and Volkswagen in the 1950~70s, when bias tires were in their heyday. His cornering force theory, called the "Fiala model," has had a great influence on the analytical models for today’s radial tires.
Tire deformation affects a car’s ride quality
The figure below is a composite image taken by a high-speed video underneath a car traveling at 40 km/hr. As an often-used metaphorical description says, tires support cars and control their movement (stops and turns) with a road contact area of just "four postcards (one postcard per tire)."
In addition, very roughly speaking, a pneumatic tire is an object made by covering the outside of an air-filled container (i.e., a balloon) with a composite material made of rubber, fibers, and metal cord. This structure, which is extremely soft compared to other automobile parts, serves as the "only point of contact between the car and the road surface" and transmits force from the vehicle to the road surface with a contact area size of just one postcard on each tire. This transfer of the vehicle’s force via the tire results in deformation of the tire. While tire deformation can impair force transmission, it also plays a critical role in reducing vehicle movement (such as shaking and vibration) during cornering or driving over uneven surfaces that provides a steady, gentler ride for the driver and passengers.
Tire condition is undoubtedly a key determinant of a car’s ride comfort. Our neo-FIALA model provides a mathematical model for analyzing tires’ ability to reduce vehicle movement (force transmission characteristics), making it easier for tire designers to organize and focus their thinking when considering a tire’s functional design.
Using a simple model structure to improve the efficiency of tire development
Yokohama Rubber’s neo-FIALA model covers three tire parts: the tread, belt, and sidewall (the main parts of a radial tire). By considering the tire deformation process, the model achieves a high degree of analytical accuracy.
Our neo -FIALA model has several mathematical formulas that numerically describe the mechanism for each tire function (braking, cornering, ride comfort, etc.), but each formula includes a very small number of parameters.
This model structure may be more abstract than a computer-aided engineering (CAE) model that generates a more-detailed structure, but it is extremely effective when using an inverse analytical process to discover what kind of tire deformation caused a certain type of tire performance.
Going forward, we will continue to expand the applications for our neo-FIALA formulas as part of the proprietary data utilization process that we will apply in this era of digital transformation (DX) to promote more efficient tire design and development.
