What emerging material innovations could make vehicles lighter?

What emerging material innovations could make vehicles lighter?

By Richik Nilay Mukherjee

In our first article, we covered the current applications of alternate lightweight materials in the automotive industry. Here, we cover some emerging material innovations to approach the challenges of lightweighting and fuel efficiency. 

Fuel efficiency is currently a predominant factor deciding the environmental sustainability of an automotive technology. The less fuel a vehicle consumes, the smaller  its carbon footprint. Recently, lightweighting of commercial vehicles has emerged as an efficient way to surge their fuel efficiency: a car’s fuel efficiency may increase by 6%-8% with a 10% reduction in its weight.

Original equipment manufacturers (OEMs) and automakers are now introducing lightweight materials for vehicles in developing countries. In these countries, the government regulations on emission controls are fairly stringent and based on a vehicle’s weight, which also attracts customers towards purchasing lightweight cars. In fact, the use of lightweight alternative materials is now trending in the worldwide automotive market as well. The global market for lightweight automotive materials expects to flourish by USD 91.3 billion, with a compounded growth of 11.4%, as reported by a recent market review.

Combining aluminum and carbon fibers: iStream Superlight

Currently, metals are the most popular among OEMs for making commercial vehicles. For instance, the global automotive market for metals is projected to cross USD 137.5 billion by 2025. Specifically, aluminum is now ruling the lightweight materials market. Reportedly, 82% of the key players in the lightweight automotive industry are using it for vehicle manufacturing.

Simultaneously, carbon fibers are also gaining popularity as an emerging material for lightweighting, with 53% of the key manufacturers currently using these composites. The carbon fibers market for automobile use is expected to reach 11,000 metric tons (MT) per year by 2025 compared to approximately 7,000 MT in 2017.

A recent innovation using both materials is iStream Superlight by Gordon Murray Design. This design produces lower emissions and a 50% weight reduction, compared to a metal body, without compromising its flexibility and stiffness. Murray plans to use this low-cost iStream Superlight technology in tiny city cars and sports cars, according to a report from March 2019.

Advantages of iStream Superlight.
Advantages of iStream Superlight. Source: Gordon Murray Design

While the technology promises to build cost-effective cars in the future, the price for a base model is still evaluated to be nearly USD 53 thousand, much higher than the other sports car models already in the market, which are below USD 29 thousand.

Combining ABS plastic and carbon fiber-reinforced plastic: Olli

Another important material that incorporates carbon fibers for weight reduction is carbon fiber–reinforced plastic or polymer (CFRP). CFRP is able to reduce weight by 10% compared to the traditional fiberglass-reinforced composites. This unique property is making CFRP a key material in automotive manufacturing, as corroborated by a recent report that predicts that the global market for CFRP in automobiles will be rapidly expanding, with a CAGR of 10.6% until 2023.

The latest innovation, Olli, is a lightweight ride-share vehicle utilizing CFRP by Local Motors. It is an eco-friendly, self-driving electric bus that is 3D printed from acrylonitrile butadiene styrene (ABS) plastic (80%) and CFRP (20%). Although Olli’s parts are recyclable and it is much lighter (5850 lbs) than presently available commercial shuttles, it still cannot achieve a speed over 25 mph and a carrying capacity of more than eight people, compared to a Type-B school bus weighing more than 10,000 lbs, which carries 10 persons. At present, Olli is serving as a university shuttle on the Sacramento State University campus.  

Next generation innovations from academia:

While many materials developments are emerging from the automotive industry, there are significant research breakthroughs from academia as well.

Combining flax seed fibers and PLA

The Lina electric car built by TU/Ecomotive, a student team from the Eindhoven University of Technology in the Netherlands, is a great example of the next generation of material innovations. The car’s body is manufactured from a bio-based composite resin made from flax seed fibers and polylactic acid (PLA).

The biodegradable resin not only makes the car eco-friendly, but also reduces its weight by five folds compared to traditional cars on the market. However, the car’s model was only demonstrated in a laboratory environment with a maximum achieved speed of 80 km/hr. Another downside of this technology is the physical property of the resin, which tends to break despite having a high strength-to-weight ratio.

A 3D-woven technical textile

Another new material comes from the University of Surrey: a 3D-woven technical textile developed in collaboration with Johns Hopkins University. This highly rigid substance can tolerate strong vibrations and provide excellent sound dampening characteristics. Initially, the goal was to make a robust and sound-proof car; but the use of 3D-woven textiles was also found to reduce weight and provide additional car space.

Figure 1
(a) 3D woven (3DW) lattice material is composed of Z- (green), warp (red) and fill (blue) wires; (b) Yellow color indicates the brazing locations (at the top and bottom). (c) Cross-section of 3D woven lattice with the stiff skeleton (the brazed portion on the top and bottom) and free lattice members in the core of the structure, (d) SEM image of the brazed top face, which confirmed metallurgical bonding of the metallic lattices. Source: Damping of selectively bonded 3D woven lattice materials in Nature Scientific Reports.

This technology, although successfully demonstrated in an academic setting, has no proven industrial benefits yet. However, it may have a promising future if tested in real commercial vehicles. At present, there is an increasing demand for textile components in lightweight vehicles, with the application of these materials surging to 35 kg in a mid-size car in 2019 from 20 kg in 2000. 

Lighter, but at what cost?

Lightweighting technologies are undoubtedly gaining significant attention in the automotive industry. However, market evaluators are questioning the cost effectiveness of lightweight cars in the future. Aluminium and carbon fibers, currently the two major lightweighting agents, are expensive to work with and further increase future auto repair costs. But despite this criticism, there are some recent successful productions and launches of lightweight cars on the market. The latest two examples are the 2020 BMW M2 CS and Riversimple’s Rasa, which are expected to hit large-scale production and commercial launch in 2020. It’s now just a matter of time to see how the manufacturers will pitch their promotional campaigns and simultaneously set a reasonable market price for these new lightweight models.  

Featured image shows the lightweight 2020 BMW M2 CS. Source: Car Scoops.

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