If a car is made 100 kg lighter, its fuel consumption decreases by about half a litre for every 100 km, according to the Fraunhofer magazine. Multiply this by the number of cars that ply on the roads, you will see that a little weight reduction makes an enormous difference. The magazine goes on to point out that if the weight of an Airbus 320 is reduced by 100 kg, it can save 10,000 litres of fuel per year.

Making things lighter is the newest tool available to mankind for fighting climate change.

Though lightweight materials are useful in all their applications, their utility is most evident in mobility. For decades, researchers have been toying with magnesium alloys for designing light-weighting automobiles, but there have been problems. According to a report, the average magnesium content in US-made cars has remained unchanged at about 5 kg for two decades. So, there is a need to move over to something else.

Researchers are therefore turning to composites, mainly carbon composites. Lightweight composite materials (LWCM) have been used in racing cars for a while — the task now is to mainstream it. Composites are an artificial combination of two different materials. The base material is called the matrix and the one bound to it is called filler. By toying with different combinations of matrices and fillers, researchers can come up with something good. But this is an arduous task. After developing each material, the scientists must test it for its ability to take different forms of stress, durability under various temperatures and other qualities such as water absorption.

This is where modern science is stepping in. Machine learning (ML) is helping fast-track material development. In a paper, researchers Nesrine Amor et al, of the Technical University of Liberec, Czech Republic, point to the growing use of computational intelligence in finding lightweight materials, especially composites. Testing the composites is also much faster and less expensive now. In the past, researchers would perform simulations to predict the material properties using ‘Finite Element Methods’— a time-consuming process. But in recent years, ‘computational intelligence’ (such as machine learning) has become the backbone of engineering. “ML methods work as excellent tools for LWCM due to their short development cycle, accurate prediction ability and strong data analysis. Nowadays, ML methods are widely used for the prediction of thermal and mechanical properties, dielectric constant and new materials design,” they say.

Scientists are finding success in bringing in lightweight materials into vehicles. Recently, the German Fraunhofer Institute announced that its applied polymer research scientists are working on a drive shaft made of fiber-reinforced plastic. Drive shafts transfer power from the gearbox to the wheels and must withstand high loads. Therefore, they have always been made of alloys of steel, aluminium or titanium. If the Fraunhofer scientists succeed, a drive shaft made of carbon fiber-reinforced plastic may become a reality. These drive shafts will be 60 per cent lighter than their metal counterparts but also have better mechanical properties.

Beyond mobility

The need for light-weighting materials goes beyond vehicles. For example, building materials could be made lighter and energy efficient. One research speaks of the immense potential that ‘lightweight concrete’ holds. The scientists investigated the merits of ‘lightweight expanded clay aggregate’ (LECA). They studied different levels of LECA mixed with conventional aggregates for making concrete and tested the lighter concrete for mechanical strength and water absorption. They found “10 per cent replacement” to be the “optimal percentage”. A cubic metre of this concrete weighs 1,821 kg, compared with 2,548 kg of conventional concrete.

But one could move away from concrete itself. Research is on for the use of alternative materials like bamboo, compressed earth blocks, fly ash bricks, and glass fiber–reinforced concrete.

“Lightweight construction is not just about making slight reductions in mass,” notes the Fraunhofer magazine. “This construction philosophy focuses on selecting materials, designing products... in a way that conserves materials and makes products lighter, while also improving functionality and safety at the same time,” it says.

In sum, lightweight materials are a new philosophy sweeping through the research world.