Tyre Sector: Living on the edge with airless tyres

April 5, 2018

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No-flat tyres were almost inconceivable with the proliferation of the ubiquitous pneumatic tyres. However, with the advent of airless tyres, the landscape of the tyre sector could soon change to create sustainable and safer driving conditions, says Angelica Buan.

The condition of car tyres is critical in safe driving. Lack of air pressure in tyres due to punctures, incorrect internal pressures, tread separation and other reasons, could result in tyre blowouts, which could be injurious, and at high speeds, be fatal.

Each year the US has about 78,000 crashes and over 400 fatalities related to tyre blowouts, according to the National Highway Traffic Safety Administration (NHTSA) data.

Globally, the Centre for Disease Prevention and Control (CDC) estimates that nearly 4,000 people are killed in road traffic crashes that are also due to various vehicle issues. By 2030, the CDC predicts that road traffic injuries will become the seventh leading cause of death around the world.

Tyre blowouts can be prevented by always checking the health of tyres, which can be cumbersome at times. Nevertheless, new tyre technologies, particularly the airless tyres, may provide a hassle-free, blowout-proof solution.

Airless tyres: a new concept

So what exactly are airless tyres? India-headquartered market analyst Insight Partners describes the tyres as “non-pneumatic tyres, which are generally not supported by air pressure”.

At first glance, the airless tyre looks odd, especially if your idea of a tyre is limited to the air-filled doughnut-shaped rubber tyre.

Leading tyre makers such as Michelin, Bridgestone, Goodyear, Kumho, Sumitomo, and several others are developing airless tyre designs based on a spoked or honeycomb structure.

The design calls for usage of plastics more than rubber. In fact, according to a report by Global Market Insights (GMI), plastics will account for a 65% share of the global airless tyre market volume from 2017-2024. Plastics make the airless tyres more recyclable, light weight, design flexible and cost effective.

Cradle-to-cradle materials

Airless tyres, which can be manufactured by 3D printing, do not rely solely on rubbers, unlike a typical pneumatic tyre that is comprised of about 47% rubber. Moreover, aside from plastics, many other materials can be potentially used in manufacturing airless tyres, including paper, wood, recycled rubber and electronic scraps. Current designs utilise recycled rubber and organic compounds.

airless-tyre

Such is the case in French tyre maker Michelin’s Vision airless tyre, an advanced version of its X Tweel airless radial that debuted in 2014. The former is described as “an innovation inspired by nature”, and fits into the company’s sustainable mobility vision and circular economy strategy.

Biosourced and biodegradable, the materials used in Vision include natural rubber, food scraps, bamboo, metal, wood and molasses. The synthetic rubber is produced from ethanol derived from molasses sugar, making the Vision tyre recyclable as a single unit at the end of its life.

Launched in 2017, Vision is claimed to be the world’s first tyre that recharges, meaning that with the aid of 3D printers, treads can be customised to fit the needs of the user. Equipped with sensors, Vision provides real time information about its condition.

Using Michelin’s mobile app, it is also possible to simply make an appointment to change the tyre’s destination, depending on the user’s needs.

In a related development, it can be recalled that environmentally-friendly materials were also worked in Bridgestone’s “Air Free” tyre concept, which it introduced in 2011, with the aim to make it commercially feasible.

The non-pneumatic tyre design features a unique structure of spokes stretching along the inner sides of the tyres supporting the weight of the vehicle. The spoke structure within the tyre is made from reusable thermoplastic resin, and along with the rubber in the tread portion, the materials used in the tyres are 100% recyclable, Bridgestone assured.

airless-tyre-bicycles

In 2013, an upgraded version was introduced with extra features such as further optimisation of the spoke structure by using highstrength but flexible highperformance resin as a material. Also, by employing finite element method (FEM) simulations in the design, stress and deformation in the inner part of the tyre was reduced for improved loadbearing capabilities and driving performance. Furthermore, the use of proprietary materials technologies and the simplification of the structure of the tyres allowed for low rolling resistance, comparable to fuel-efficient pneumatic tyres.

Since then, further upgrades followed and come 2019, Bridgestone is expected to make available in the market its next generation bicycle tyre – a result of further development of the airless tyre concept.

Structures redefined

Meanwhile, compatriot Goodyear has utilised thermoplastics in its airless tyre it introduced in 2017. The thermoplastic

absorb-impact

structure provides a unique combination of stiffness and flexibility to carry heavy load, while maintaining a smooth ride and minimising turf tear, says the US firm. It was designed to “deform, absorb impact, and create a smooth ride every time”. The non-pneumatic TurfCommand with DuraWeb technology is expected to be available this year.

The technology, according to Goodyear, is part of the company’s strategy to develop maintenance-free technologies for passenger and commercial vehicles, particularly in fleet applications.

For South Korean tyre maker Kumho Tyres, its nature-inspired Birth on Nature (BON) tyre takes on a typical voronoi quadratic architecture in the form of leaf cells and the honeycomb. The design enables structural stability and economic efficiency of the tyre, without the need for any form of inflation, says Kumho.

Kumho-features

Already, Kumho’s concept tyre, has swept various awards, namely, Germany’s Red Dot and iF Design, and the US IDEA awards in the automotive and transport category.

Milestone for airless tyres in space

Further R&D in airless tyres has led to the discovery of other materials beyond plastics and rubbers due to the limitations they present, especially in space explorations!

Since the 1970s, Goodyear has been developing non-pneumatic technologies and in recent years, has collaborated with the National Aeronautics and Space Administration (NASA) for space tyre projects. Most significant were Goodyear’s work with NASA’s John H. Glenn Research Centre for moon tyre technology in 2007 that featured an airless non-rubber wire mesh tyre for the Apollo Lunar Roving Vehicle (LRV) to allow for use of heavier, longer-range exploration and lunar construction vehicles. In 2009, it developed the Spring Tire with 800 load bearing springs designed to carry much heavier vehicles over much greater distances than the wire mesh tyre previously used on the LVR.

Evolving from the Spring Tire, but this time with improved features such as traction in soft sand, durability, and lighter weight, the NASA Glenn scientists, led by Colin Creager and Santo Padula, have developed a non-pneumatic prototype tyre. Called Superelastic Tire, it utilises shape memory alloys, nickel titanium (NiTi and its derivatives) as load bearing components.

Superelastic-tire

The innovation also addressed issues such as steel wires deforming when rolling over punishing simulated Martian terrain at NASA’s Jet Propulsion Laboratory (JPL).

NiTi alloys are capable of undergoing high strain as load bearing components and able to withstand excessive deformation without permanent damage, unlike commonly used elastic-plastic materials, such as spring steels, composites, and others, which can only be subjected to strains of less than 0.3-0.5% before yielding.

In addition, the utilisation of shape memory alloys provides enhanced control over the effective stiffness as a function of the deformation, providing increased design versatility.

The innovation, according to NASA, has been developed for future Mars missions. And especially since it is gearing up for the one-way red planet expedition in 2024, airless tyres may take up the monumental mission.

For the meantime, airless tyres are being developed as viable alternatives to pneumatic tyres here on earth. This is because the Superelastic Tire offers traction equal or superior to conventional pneumatic tyres and eliminates the possibility of puncture failures, thereby improving automobile safety. This tyre design also eliminates the need for an inner frame, which both simplifies and lightens the tyre/wheel assembly, NASA added, and thus implying that the NiTi airless tyre is almost indestructible.

In other words, Superelastic Tire can be further developed for practical application, such as for all-terrain vehicles, military vehicles, construction vehicles, heavy equipment vehicles, agriculture vehicles, cars and aircraft.

Future demand not flat

Because most airless tyres are yet to be produced on a commercial scale, developments on prototypes are still ongoing. Nevertheless, the market for these nonpneumatic tyres seems lucrative.

According to GMI, the market for airless tyres is valued over US$200 million, reaching 139,000 units by 2024. Over the forecast period from 2017-2024, the demand is anticipated to come from off-the-road and heavy commercial vehicles segments and from rising adoption by the military sector, especially in developed countries.

More golf carts, lawn mowers, and other utility vehicles will soon be sporting airless tyres, thus contributing to the growth of the market. And soon yet, as more innovations unfurl, personal vehicles and aircraft will also run on airless tyres.

Road safety as well as the clamouring for light weight and fuel economy cars is encouraging automobile OEMs to adopt airless tyres in their vehicles, GMI stated.

Japanese automotive manufacturer Toyota has tried out Sumitomo Rubber’s Gyroblade airless tyre in its Fine-Comfort Ride concept car, which it introduced at the Tokyo Motor Show in 2017. The car maker says it is looking into the promising capability of airless tyres to accommodate heavier hybrid cars.

Gyroblade-airless-tyre

Gyroblade, introduced in 2015 by Tokyo-based Sumitomo, features a tyre tread affixed to the circumference of a tyre body that is composed of metallic steel surrounded by special resign spokes.

According to Sumitomo, the technology not only assures safety from underinflated tyres and significantly reduces maintenance work, but also contributes to the environment by eliminating the need for spare tyres.

With the demand for longer lasting tyres that are safe and environmentally-friendly, it is not surprising that in the near future, with electric vehicles plying the roads and utility vehicles requiring tyres that can withstand heavier loads, airless tyres will become a mainstream item.

(RJA)


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