Using this new technique to measure rotating tires has led to the discovery that the tire’s lateral stiffness in the rotating condition is not constant from the start to end of the cornering test, even though it is treated as a constant value in conventional vehicle motion simulations. This new fact could lead to more accurate vehicle motion simulations and speed up tire development in the future. Measurements are ongoing and the latest results were presented at the 2016 Tire Technology Conference. Engineer Ryoji Hanada reveals more.
Please tell us about your role at the company.
I am in charge of the development of new tire structure technologies. On the business side, I develop new test methods and provide a plan for improving tire performance using these newly developed test methods. For example, many racing tires used in Japanese championships use technologies that I developed. Notable achievements include my prize for an article as the first author from a tire company to be honored by the Society of Automotive Engineers of Japan. At Yokohama, we believe this win shows the company’s technical contribution to the automotive industry. I am also in charge of collaborative projects with Japanese and American universities and I am a fellow of the Society of Automotive Engineers of Japan.
What is the new non-contact shape measurement method that you’ve developed?
We started to develop the non-contact 3D shape measurement method for tires in cooperation with the Wakayama University in 2009. First we developed a method that enabled the qualitative measurement and measured the strain on the tire sidewall area in cornering and braking.
Based on the measurement method stated previously, we made an improvement and succeeded in measuring the tire lateral stiffness on a rotating tire for the first time ever.
In our presentation at Tire Technology Expo 2016, we reported the measurement results of the tire lateral stiffness on a rotating tire and showed that this is not constant from the start to end of the cornering test, for the first time ever. The tire lateral stiffness is treated as a constant value in a conventional vehicle motion simulation. This has the potential to improve the accuracy of vehicle motion simulation.
How does it work?
Digital image correlation (DIC) is a well-known non-contact method for analyzing the deformation behavior of a tire rotating at high speed. However, the current method is not accurate enough to recognize a small difference between test tires’ deformation. Our method achieves a much higher measurement accuracy. It enables the measurement of different phenomena occurring on a tire’s tread and it enables us to calculate precise improvement of the simulation for performance enhancement. Using our non-contact method, tire pattern deformation at the contact patch area can be measured by a single image on a rolling tire. These results can be used in tire pattern design and development, and in research of tread wear.
Through our analysis we have established two important facts: tire lateral stiffness just after the slip-angle input is different from the tire lateral stiffness rotating at the constant slip-angle input; and tire lateral stiffness just after the slip-angle input appears to have an association with vehicle feeling evaluation results.
We are now pushing forward improvements to enable a tire designer to easily utilize the system for tread pattern design.
26 May, 2016