Lightweighting can be defined as “the process of making an object that weighs less without compromising its strength or performance,” states the American Society of Mechanical Engineers (ASME). This process is particularly popular among automobile and aircraft manufacturers aiming to decrease weight to increase fuel efficiency. Lightweighting can also improve durability, maneuverability, and acceleration in cars, and reduce the carbon footprint associated with making vehicles and planes, notes the ASME.
Lighter weights are usually attained by swapping heavy parts for lighter ones, using fewer components, and optimizing designs. The first method comes with a serious caveat: materials for airplanes and cars need to be rugged, tough, and resistant to corrosion. A tinfoil plane or car would certainly be lightweight but hardly practical or safe.
Given this, automotive and aerospace manufacturers often use composites for lightweighting. Composites are created by blending materials to produce a strengthened hybrid material. Concrete—a mix of cement, water, gravel, and sand—and plywood—created by affixing multiple layers of thinly cut wood together—are examples of composites used in daily life.
In automotive and aerospace circles, fiberglass—polymer resin mixed with glass fiber—and carbon fiber reinforced polymer (CFRP) are commonly used composites. The latter is particularly prized for its strength and is several times stronger than most metals while being significantly lighter. Metal and plastic decorative vehicle parts can be substituted with components made from polyurethane foam. Aluminum alloys, magnesium alloys, and steel alloys are also popular in automotive and aerospace.
Composites are typically used in tail and wing sections, fuselages, and interior components in airplanes, says “Materials Matter: The Science of Lightweighting in Aerospace,” a September 12, 2024 article in Quality magazine.
During World War II, the de Havilland Mosquito, a British plane made partly with laminated wood, was one of the first aircraft to feature the widespread use of composites. After the war, aerospace mogul Howard Hughes spearheaded development of the H-4 Hercules flying boat, aka “the Spruce Goose.” An enormous, eight-propeller transport plane, the Spruce Goose featured thin, laminated layers of birch. While the Spruce Goose was not lightweight and never entered commercial production, it pointed the way forward in terms of innovative use of composites.
Skip ahead to 2009, and the Boeing Corporation of Chicago introduced the pioneering 787 Dreamliner, a passenger jet with a structure comprised of 50 percent composite material. “The 787 Dreamliner was the first commercial passenger aircraft designed with advanced composite materials in the wing, fuselage, and empennage primary structure,” states the Hexcel Corporation from Connecticut, which provided advanced composite materials for the aircraft.
By utilizing CFRP among other composite materials, Boeing reduced the weight of the 787 Dreamliner by one-fifth compared to a typical plane. Hexcel provided advanced composites for other Boeing passenger jets such as the 737 MAX and 777X.
In 2013, Airbus of France introduced a composite-containing plane of its own, the A350 XWB passenger jet. Once again, almost half, by weight, of the A350 XWB consisted of composite material. Airbus aims to produce zero-emission commercial planes in the near future, a challenging goal that will almost certainly require greater use of composite materials.
Composites have also been featured in spacecraft, which makes sense given that anything sent into outer space needs to be both ultra-low weight and extremely fuel-efficient. Unlike airplanes, spacecraft cannot make emergency landings if they run low on fuel due to unforeseen circumstances.
“Composites have been used in space applications for decades and their use continues to grow. Composite applications can be found in human spaceflight vehicles, satellites, and payloads, and the launch vehicles that are used to get these to space,” according to the Society for the Advancement of Material and Process Engineering (SAMPE), adding that, “Solid rocket motors and pressure vessels for fuel and gas storage are typically reinforced with composites.”
Composites are “the standard for ablative and other high-temperature components in rocket motor nozzles and re-entry heat shields dating back to the Apollo era,” the society continues. High-modulus, carbon-fiber-reinforced laminates are commonly used on spacecraft while carbon fiber laminates are commonly used on payload support structures and satellites.
In the automotive sector, General Motors was one of the first domestic manufacturers to use composites in a major way. The 1950s-era Chevrolet Corvette was built with fiberglass body panels, a pioneering move at a time when such parts were usually made from steel. During the 1970s, the Organization of Petroleum Exporting Countries imposed tighter controls of oil exports, causing gas prices to skyrocket and spurring further interest in lightweighting.
“Replacing heavy steel components with materials such as high-strength steel, aluminum, or glass fiber-reinforced polymer composites can decrease component weight by 10 to 60 percent,” notes a U.S. Department of Energy report. “A 10 percent reduction in vehicle weight can result in a six to eight percent fuel economy improvement.”
In 2015, the Ford Motor Company became a lightweighting leader when it used aluminum instead of steel in the body of its F-150 pickup truck. Switching to aluminum reduced the truck’s overall weight by roughly 700 pounds. The F-150 proved enormously popular and Ford used aluminum on subsequent models such as the F-150 Lightning, a fully electric pickup truck.
Two years after the groundbreaking F-150 model was introduced, Fiat Chrysler used magnesium to lightweight its Pacifica minivan. GM’s Sierra pickup truck for 2019, meanwhile, boasted a CarbonPro truck bed made from advanced carbon fiber/thermoplastic composites.
In addition to being more fuel-efficient, such vehicles “can carry additional advanced emission control systems, safety devices, and integrated electronic systems without increasing the overall weight of the vehicle,” notes the Department of Energy report. Lightweighting is particularly beneficial for offsetting the weight of heavy batteries and motors in hybrid and electric vehicles, adds the Department of Energy.
Optimizing design is another way to lightweight planes and cars. The general concept is to use advanced technologies such as computer-assisted design (CAD) software to enhance existing designs or create new designs that emphasize lower weight. Custom molding can also be part of the process. “Rather than machining a sheet stock or block into the component’s shape, a custom tool is designed to mold the part from a lightweight material,” reads “How Light Can You Go?” a technical paper from General Plastics Manufacturing Company of Tacoma, Washington.
Thermoforming is another factory-floor method applicable to lightweighting. “This drape or mold forming process is easy to use and ideal for shaping shallow slopes and angles where machining would be more wasteful or time consuming,” states the paper.
A final method is to simply use fewer components. “As production processes and materials evolve, components can often be removed from assemblies entirely, while still meeting structural, flammability, and thermal requirements,” notes a May 9, 2022, blog post titled “What is Lightweighting and Why is it Important?” from the Boyd Corp, a firm that specializes in thermal solutions and sustainable engineered material.
Additive manufacturing will likely prove to be a wildcard within lightweighting circles. For aerospace production, the benefits of using 3D printing and advanced manufacturing techniques include design freedom where “engineers can create parts with complex geometries without sacrificing precision or increasing waste,” says Axiom Materials, Inc. of California. Other benefits include weight reduction and rapid prototyping. “Because prototypes can be manufactured more quickly, the entire design and testing process moves along at a faster pace,” says Axiom. Many of these points can apply to automotive manufacturing as well.
Still, 3D printing is slow compared to traditional production processes and is typically reserved for making spare parts or speciality items rather than mass-producing parts at this time.
While much of the focus on lightweighting concerns airplanes and automobiles, other manufacturers are also embracing the trend. “In the consumer electronics and medical industries, lowering the weight of a wearable or handheld device can enhance user comfort, extend the amount of time between recharging, and reduce shipping costs,” notes the Boyd Corp report.
For all that, automotive and airplane makers have a vested interest in creating lighter but durable versions of their vehicles and planes, and to this end, researchers continue to explore the use of new composites and other lightweight materials.
Growing environmental awareness among the public will likely hasten the move toward lightweighting. Manufacturers are eager to position themselves as green, and reducing fuel consumption by reducing weight is a good way to go about this. Government fuel mileage mandates are another spur, while advances in technology are making it easier to develop lightweight-friendly designs.
“Advanced software tools, incorporating techniques like topology optimization, artificial intelligence (AI), and machine learning (ML), enable engineers to design lighter and stronger components by removing excess material while maintaining structural integrity,” notes Materials Matter: The Science of Lightweighting in Aerospace. “AI and ML can analyze vast amounts of data to identify optimal design parameters, predict performance outcomes, and continuously improve design efficiency.”
