Material Matters

Original article was published on Autonomous Vehicle Technology


Equipped with a plethora of sensors and increasingly electrified, connected and autonomous vehicles of the future will require a fundamental rethink about the nature of materials.

While breakthroughs in battery technology may help lighten the load, OEMs will need to work with chemical companies and other partners to develop durable components that allow sensors to transmit signals without interference.

“The move to electrification will substantially increase the durability, or lifetime, of the vehicle,” Lux Research Senior Analyst Anthony Schiavo explained. “While batteries have a somewhat limited life, EVs overall have fewer moving parts, are subject to less vibration, and maintain a narrower range of temperatures than combustion powered vehicles.”

If an EV is constructed in a body-on-frame arrangement, the frame and drivetrain will likely still be functional long after the interior and exterior of the vehicle have become worn out.

“Our analysis of the space found that automakers account for 23 percent of the investment in future vehicle technologies, the second largest group after electronics companies like Intel, Samsung, and Huawei,” he said. “With that said, the coming transitions in electrification and automation do not require any changes in materials.”

The costs of batteries have fallen from between $1000 to $800/kW·h a decade ago to $100/ kW·h today, while the costs of lightweighting have remained mostly constant.

“Due to these costs, our modeling has shown that, for passenger vehicles, the cheapest option to extend range will be to increase battery pack size, even though batteries add weight,” Schiavo noted.

While the evolution of the materials used in the automotive industry are not exclusively determined by electrification or autonomous driving, electric vehicles require materials that should allow a good electronic integration, high thermic dissipation, better electric isolation, and electromagnetic protection.

In the case of autonomous driving, the use of radars requires very tight thickness tolerances, while sensors should meet many parameters both in their location and in the geometry of the environment.

At Spanish automaker Seat, the company is already using materials in its vehicles that allow proper radar signal transmission, which is important not only for autonomous driving but also for current advanced driving assistance systems (ADASs).

These materials, which are mostly placed in front and rear bumpers, fulfill strength and lightness requirements, and they will also be used in other places of the car due to the increasing number of sensors required for new and improved ADAS architectures.

Dr. Thomas Bayerl, Segment Marketing Manager for E&E applications at BASF, explained that plastics experts at the company are improving materials for sensor housings, providing them with a higher durability and resistance toward environmental challenges or improving the electromagnetic transparency.

“Metallic body panels usually block the view from sensors and thus sensors are usually mounted behind transparent materials such as plastics,” he said. “However, even behind a transparent material, the sensor beams interfere with all layers which they need to pass.”

A variety of factors—including bumper substrate, thickness, and geometry; positioning of the radar sensor; usage of primer and its type; coatings layer thickness in general; as well as coatings process and repair film-builds—could all influence radar attenuation.

For these reasons, BASF’s coatings division works in close collaboration with each OEM customer to develop coatings applied in the range of radar sensors, all aimed at supporting high radar attenuation.

“We have already formed partnerships with OEMs to jointly work on new materials, innovative applications and future requirements,” he added. “We are always looking for new and innovative materials that contribute to e-mobility or automated driving.”

Rinspeed CEO Frank Rinderknecht said light weight is the “key issue” for the industry, because the more weight one can save while building the vehicle, the less energy needed to move it. That, in turn, increases the performance and also allows OEMs to compensate for the additional weight of new elements like computing platforms and sensors.

“The automotive industry, per nature a slow one, is based on costs,” he noted. “New materials are generally more expensive, and the OEM will carefully compare savings versus costs.”

In his view, the exterior materials will generally not be changed, although there might be applications, such as hiding or integrating sensors, where materials will be used that do not interfere with the performance of those sensors.

“In our view there would be a wide field of weight-saving measures,” he said. “However, they might also interfere with marketing claims, customer expectations, and engineering goals or values.”

With swappable bodies, the likes of which Rinspeed is developing, one can overcome that big obstacle and also increase the efficiency of the vehicle in use, Rinderkneckt said.

Lux Research’s Schiavo also pointed out shared mobility will accelerate fleet ownership rather than personal ownership of vehicles.

“Beyond the use of more durable materials, this mismatch between the lifetime of the structure and the interior can create a whole new industry structure,” he said.

He predicted OEMs could become suppliers of rolling stock, which contains all the necessary components to make a vehicle drive but without an interior and, potentially, no exterior.

“Fleet operators could then fit these rolling stocks with bodies and interiors as they see fit and continuously refresh these rolling stocks with bodies as they age,” Schiavo explained.

BASF’s Bayerl noted a powerful electric drivetrain is much more dependent on an efficient cooling system and a densely packed battery, and BASF is contributing to this with solutions to use engineering plastics in e-mobility drivetrains that allow versatile designs and offer the possibility for function integration.

He said that flame-retardant plastics also offer new ways to design batteries in a different way for achieving a higher energy density of the battery pack.

“Moreover, we are working on setting standards in cooling electric powertrains with our solutions for coolants out of our Glysantin portfolio, which are already in use in various electric vehicles today,” he said.

Coolants for electric vehicles are designed to achieve the highest possible heat uptake and dissipation to allow for maximum lifespan and driving range.

With more high-voltage parts entering the proximity of the coolant circuit, the coolant’s safe operation under these conditions requires careful adaption of parameters such as conductivity, corrosion protection, and flammability.

“But there is also a contribution to overall weight reduction: The more efficient a coolant is, the less volume—and weight—is needed,” he said.