High-temperatures in the region of 80o C, traction load of 750 kg, water evacuation capacity of up to 30 l/s, deformation of up to 150 % and an impact force of up to 300 kg/ cm2. These are only some of the challenges faced by a tyre during a regular daily run.
Discussions on future mobility and talks about engines, hybrids, EVs, fuel-cells and lightweighting are important and common world over. However, one critical area often ignored is that of tyres, even though it serves as the contact point between the vehicle and road surface. As a matter of fact, tyres have been undergoing tremendous development over the years, and one company leading the pack is Michelin. Dominique Aimon, Vice-President, Technical & Scientific Communication, Michelin Group was in India recently, and Auto Tech Review was invited to a technical discussion.
TYRES FOR BETTER MOBILITY
UN-based data from Gapminder showed that development and road mobility are strongly co-related points globally. About 80 % of the present world’s mobility takes place on roads, further highlighting the role tyres can play in environmental preservation. Aimon pointed these out as a perspective on the challenges for future mobility market.
Michelin has offered industry-defining innovations over its 125-year-old journey, and every passing year has brought forward newer challenges to future mobility, Aimon commented. To put things in perspective, vehicle population, which stood at 50 mn in 1950, increased to about 800 mn in 2000 and could reach or exceed two billion by 2050. With increasing cost of fuel and the need to lower emission, tyres too can play a role in making future mobility, safer, cleaner and more efficient.
To understand the possible areas of improvements, Aimon first took us through the hardships for a tyre. In order to overcome such arduous challenges regularly, without any noticeable drop in performance, it becomes important to use composites for making tyres. Aimon told us that the composites used in a tyre have more than 200 components across multiple layers.
A key design challenge for tyres is to achieve balanced performance in areas such as longevity, dry grip, wet grip and fuel saving. Keeping these factors in mind, Michelin had developed the Energy XM2, which owing to its IronFlex technology, offers a balanced performance in all the discussed areas, said Aimon.
Talking of the need to focus on improving tyre efficiency, he told us that over 92 % of a tyre’s lifecycle energy requirements are during its stage of usage. A surprising fact revealed by him was that about 4 % of the world’s carbon emissions are due to tyres. Adding further, he said that of every five full-tanks in a car, about one tank is used up by the tyres alone. In terms of impact of a car on the environment in the city, there is a higher impact of particulate emission from the exhaust of a car due to the tyres’ rolling resistance than the impact of the particulates of the tyre emitted due to wear.
Now why does a tyre need such amounts of energy? Aerodynamic drag and slippage on the surface, which come first to the mind only contributes to about 15 % of the energy requirement. The remaining major chunk of requirement arises from the bending, compression and shearing of the tyre’s tread and the sidewall and bead area.
SOLUTIONS FOR FUTURE
In order to overcome the discussed challenges, Aimon gave us a peek into the solutions being worked upon for the tyres of tomorrow. The present and upcoming hybrid and electric cars will make use of a taller and narrower design for tyres since they offer lesser rolling resistance and better aerodynamics. He later added that narrowing the tyre won’t lead to loss of grip as suggested by the usual conception. A tyre’s grip depends on the area of the overall contact patch with the surface, among other factors, and not necessarily restricted to horizontal expansion only.
A unique challenge Michelin has taken up is in the form of becoming the official tyre supplier to the upcoming Formula-E electric car racing series. While F1 tyres are usually considered to be at the pinnacle of tyre technology, their size has been stuck at just 13 inches for over two decades. Formula-E tyres instead will use 18-inch tyres, which will experience acceleration loads a little below what F1 tyres do. Also, unlike F1, Formula-E cars will use a single all-weather tyre. In line with the design philosophy mentioned earlier, these tyres are taller in order to offer higher efficiency and in turn a better range from the car’s battery.
These solutions are being developed by Michelin’s global R&D team, which comprises of more than 6,600 people across 350 fields of expertise. Putting numbers to Michelin’s testing and simulation capabilities, Aimon told us that about 140,000 hours of simulation is generated every month. Also, 11 tn computing operations are carried out by Michelin globally every second. On the back of such a strong R&D team, Michelin is also working on distant future technologies such as active-wheel, which could redefine the way cars are designed.