The automotive industry has been reinventing itself to become more and more sustainable, starting with automotive lightweighting: the replacement of metal parts with lighter materials that can be recycled or reused at the end of the use cycle, such as plastics, which weigh up to 50% less compared to traditional automotive materials. Thirty years ago, only 5% of the total weight of vehicles was made of plastic. Currently, the volume is around 20%, and it is projected to reach 25% in the near future.
The range of potential applications for lightweight materials has continuously increased in recent years. Especially in the automotive industry, there are more and more applications for lightweight materials, as a significant reduction in CO2 emissions can only be achieved through considerable weight reductions in vehicle design. For this reason, hybrid and lightweight design solutions are now integrated into almost all future vehicle components.
3 state-of-the-art automotive lightweighting strategies:
The advantages of a lighter car are many. Since the engine has to use less force to move the vehicle, it doesn’t need to be very powerful, and the use of energy (or fuel) in the process is lower. A vehicle with less mass is also safer, as the structure has to absorb less kinetic energy in the event of an accident. Also, the dynamics tend to improve, with a lower center of mass, more agile accelerations, shorter braking distances, and a more balanced weight distribution between the axles. The final frontier of consumption efficiency is aerodynamics. But it has a catch: it only makes itself felt at higher speeds, in which the resistance of the air requires a much greater expenditure of energy.
As will be discussed in this article, there are three key strategies for lightweighting automobiles:
- Replacement of traditional iron and steel with aluminum and composites in car parts
- Replacement of components that practically all cars have with new useful materials such as banana leaves, hemp, and soy, which are lighter for the production of vehicles
- Use of less powerful engines that require less fuel
Lightweighting of essential automobile parts:
BMW, with its new modular CLAR platform, applies Carbon Core technology to the Series 7 chassis by strategically placing carbon fiber, aluminum, and high-strength steel, while Mazda has been working to replace all lead-acid batteries in its cars with much lighter lithium-ion units.
For the Volkswagen group’s MQB modular platform, first adopted on the Audi A3 and the Golf 7, using technologies such as sheet metal with different thicknesses at various points, hot-formed components, and high- and ultra-strength metals (which are often cheaper than aluminum or carbon fiber), VW was able to eliminate 100 kg of the new Golf compared to the previous model.
Ford uses aluminum bodywork on the F-150 and produced the Fusion Lightweight Concept that weighs the same as a Fiesta. The secret is spread throughout the car. The bodywork has steel replaced by aluminum in every possible place, even in the unibody. Brake rotors, usually cast iron, are also made of aluminum. The crankcase, dashboard, seats, and various interior components are made of carbon fiber — as are the very narrow 19-inch wheels. The stabilizer bars, crankshaft, and rear springs are still steel, but are now hollow, while the front springs are composite. All these modifications lightened some 800 pounds of the Fusion’s weight.
Innovative materials for other automobile components:
In addition to the components that practically all cars have, the development of the automotive industry has researchers finding new materials that are useful for the production of vehicles every day. For example, magnesium, being 74% lighter than steel and 33% lighter than aluminum, is already commonly used in sports wheels.
There are also more unusual materials, such as banana leaves, hemp, and soy. The first was used in the manufacture of carpets for the Lincoln MKT SUV model, as it is more heat resistant – and also a more ecological alternative. The second is present in the Lotus Eco Elise. The edition of this model made from hardened hemp fiber weighed 32 kilos less. Finally, soy foam is a technology advocated by the Ford group that provides an ecological alternative to synthetic upholstery.
Eco Elise panel is made with Cannabis Sativa fibers
Image courtesy Lotus Cars
More fuel-efficient engines:
With Ford’s adoption of the 1.0 Ecoboost turbo three-cylinder engine for the Fusion Lightweight Concept, the fuel economy is also the same as that of a Fiesta — about 45 mpg. And the low weight guarantees a car that runs as well as a Fusion with a 2.5 liter engine.
Impact on vehicle efficiency and new functionalities brought about by lightweighting:
Aerodynamics, weight, and powertrain are key elements to tackle to reduce emissions and help save fuel. According to a study by Finland’s VTT Technical Research Center, a 10% lighter car would deliver fuel savings of between 6% and 7% compared to a similar but heavier car.
The Advanced Materials for Transportation Technology Collaboration Program (AMT TCP) aims to pioneer materials innovations to accelerate energy efficient technologies to reduce carbon emission and assess current and future materials technologies for the most cost-effective technology transformations.
The technical activities of AMT Vision are divided into 5 Annexes:
Thermoelectric and thermal management;
Model-based coatings; Multi material joining;
Automotive glazing; Tailored surface engineering.
Source: IEA-TCP-AMT.org
The development of plastics for use in vehicles benefits the industry in several ways, from the cost of purchasing parts to the delivery of sophisticated cars, with wide design freedom and lighter weight promoting fuel economy, reducing emissions, and allowing the sector to provide quality and comfort in a sustainable way.
In addition to its role in the reduction in weight, the increased use of plastic in vehicles is also due to advances in the development of polymers and improvements in plastic stabilizers and dyes. BASF explains that these solutions play an important role in the conservation and strength of the pieces. They are light stabilizers and UV absorbers that prolong service life and maintain the appearance and properties of the plastic applications. For interiors, for example, in addition to the thermal stabilizers Irganox and Irgafos, BASF has also developed the Irgastat line, which prevents the accumulation of dust on parts such as the car’s dashboard.
The contribution of plastic goes beyond this, to also enable recycling and a circular economy. A recent reinforcement in this regard is BASF’s ChemCycling initiative, which uses pyrolysis oil derived from plastic waste as a raw material in its own production, as a substitute for fossil resources. In this way, plastic waste is transformed into new, high-quality materials. In a pilot project, Jaguar Land Rover is already testing the material on a front part of its first 100% electric model, with the aim of evaluating the use of recycled material on a large scale in vehicles in the future.
Conclusion:
As discussed, there are three main elements to address in making cars more fuel efficient: aerodynamics, weight, and engine. The more aerodynamic and lighter a car is and the more efficient its engine runs, the less the driver of the vehicle will spend to refuel.
However, a major problem with lighter materials is cost. “Weight is expensive to reduce.” Data from a study by the International Council on Clean Transportation show that a mass reduction of around 5% adds a little more than USD $ 1,000 to the cost of the vehicle. If the reduction is 10%, the cost rises to something close to $2,000. If it is 20%, the increase exceeds $3,000.
All lightweighting decisions are made with the industry’s logic of achieving the maximum gain for the smallest possible output. With this, the search for innovation in the manufacturing process and new materials to replace the previously used metals has been the main objective to ensure the lightness of cars. Considering the logic behind the creation of automobiles, which requires millions of calculations and considerations, it can be said that we are moving toward having vehicles that are lighter, more aerodynamic, and equipped with more efficient engines.
