With the increasingly stringent emission regulations and the mandatory demand for fuel economy, in addition to working hard on power, reducing the weight of vehicles as much as possible has also become a major task for car companies. The weight loss mentioned here is not cutting corners. In professional terms, it is lightweight.
​​
The lightweight of the car is to reduce the curb weight of the car as much as possible on the premise of ensuring the strength and safety performance of the car, thereby improving the power of the car, reducing fuel consumption and reducing exhaust pollution. For every 100 kg reduction in the curb weight of the car, the fuel consumption per 100 kilometers can be reduced by 0.3-0.6 liters. Due to the needs of environmental protection and energy saving, the lightweight of automobiles has become the trend of automobile development in the world.
​​
In terms of lightweighting of automobiles, in conclusion, it is usually used to replace lighter materials. This method is the simplest and most effective, but lighter and stronger materials will lead to higher costs. Therefore, the optimization of the body structure and components, the improvement of structural strength, and the reduction of the amount of materials are also considered one.
​​
At present, car companies have their own choices of R&D and development paths in the lightweight field. Let me take a look at the representatives of the most representative car companies in various fields.
​​
Audi is the first to advocate the concept of an all-aluminum body, like the flagship Audi A8, which is based on an all-aluminum structure. Audi didn't hold out, though, and the new Audi A8 is noticeably heavier. Mercedes-Benz's all-aluminum body design is a match for Audi. The new-generation Mercedes-Benz E-Class made in China is heavier than the overseas version, because the Mercedes-Benz E-Class replaces the doors and hood from aluminum with steel. Needless to say, Tesla is a newcomer and is currently only at the stage of trying out an all-aluminum structure, but only models under Jaguar Land Rover have been insisting on this.
​​
Take Jaguar's new-generation XFL as an example. It is a new car developed based on Jaguar Land Rover's latest modular intelligent all-aluminum body structure. The weight reduction effect of the Jaguar XFL after adopting the all-aluminum body structure is very obvious. The curb weight of 1590KG is basically equivalent to the lower B-class car. Competitors BMW 5 Series, Mercedes-Benz E-Class and Audi A6L all weigh around 1750-1760kG. There is no doubt that the Jaguar XFL is at least 160KG lighter than these models.
​​
The all-aluminum body is not simply replacing steel with aluminum, but also involves redesign and consideration of body strength and structure. And aluminum can't use the spot welding process to solve the splicing problem like steel, but requires riveting instead of spot welding, and with the gluing process, so the use of an all-aluminum body involves very complex links, requiring enterprises to have a large number of It is very difficult to control the cost within a reasonable range with extensive experience in aluminum application.
​​
At present, Jaguar Land Rover's models all use a large amount of aluminum to varying degrees. In order to improve the sports performance of the vehicle and achieve better performance, a large number of aluminum parts are also used in the chassis. In addition to reducing weight, it can also Improve the responsiveness and agility of the entire chassis.
​​
The full English name of carbon fiber reinforced composite material is CarbonFiberReinforcedPolymer, and its density is usually about 1.7g per cubic centimeter, which is far lower than the steel commonly used in manufacturing. In an environment up to 2200 °C, CFPR can still retain room temperature strength, and fracture toughness, fatigue resistance, creep resistance tensile strength and elastic modulus are higher than ordinary carbon materials. Before civilian cars, CFPR has been widely used by the aerospace industry. From Boeing 787 airliners to F-35 stealth fighter jets, carbon fiber materials are magic weapons to reduce weight and reduce thermal expansion coefficient.
​​
However, the cost and manufacturing difficulty are obstacles to the large-scale application of carbon fiber. Most of the carbon fibers we see in cars now appear in the form of interior panels, roofs, hoods and other components, and most of the cars with this design are high-performance cars, which are expensive. And those that can use carbon fiber cockpit or body are basically top-level super sports cars (for example, McLaren's sports cars are all carbon fiber cockpits), and the civilian level is only seen on the BMW i series.
​​
Now we can buy the cheapest carbon fiber body model in the market, only the BMW i3. Its cheapest official guide price is 420,000 yuan, and it is less than 300,000 yuan after having a terminal discount. This is for a car with a carbon fiber body. It is very powerful to control the cost to this level, which shows how profound BMW's accomplishments in the field of carbon fiber are.
​​
However, BMW is going to give up carbon fiber on the new-generation i3 and use aluminum alloy material. The high cost is only one aspect. The main problem is that the after-sales cost is higher, and the repair can only be done by replacement. Once the body structure is damaged, only the overall carbon fiber body part assembly can be replaced, and the cost is too prohibitive for consumers to buy an i3. Therefore, BMW has adopted the application of local carbon fiber in the new generation of 7 series, and applied the advantages brought by the characteristics of carbon fiber to the blade.
​​
The new-generation 7 Series has a core material made of CFRP inserted into the inner side of the closed section made of steel plate, which improves rigidity and strength while reducing the weight of the car body. The weight of the new-generation 7 Series is reduced by 130kg compared with the previous generation model, the body frame is reduced by about 40kg, and the torsional rigidity of the body is strengthened.
​​
Ten years have flown by since Ford introduced soy-based seats on the Mustang in 2008. Ford said it has used the biomaterial in at least 18.5 million vehicles.
​​
In 2008, the year that oil prices skyrocketed, Ford Motor began producing foam from soy extracts, mainly for car seat cushions, backrests and headrests. For 10 years, Ford researchers have developed a series of biomaterial-based products. For example, the materials used for thermal insulation are coconut fiber, reinforced resin and denim chips, while kenaf can be used to make door frames and battery boxes, and more open-minded materials have also been included in the research scope, including: Collected carbon dioxide; tomato seeds; dandelion; bamboo; seaweed; agave fiber!
​​
Like the front and rear doors of the Mondeo, kenaf fiber-reinforced materials are also used, which can reduce the weight of parts by more than 30% compared to traditional materials. In addition, rice husks, coconuts, cotton, and soybeans can be magically transformed into raw materials for automobile manufacturing. The application of biomaterials can not only reduce vehicle manufacturing costs, but also meet the current stringent requirements for environmental protection.
​​
Finally: From the perspective of the development direction of these three car companies, carbon fiber will definitely become a hot material, aiming to greatly reduce the weight of the body. However, due to its high price and not a large number of applications, the way out for carbon fiber may be more suitable for the application of super-high-priced supercars. On the contrary, aluminum alloys may be a good way out. As long as car companies improve their assembly lines and processes, they can effectively reduce the cost of aluminum alloys to a certain extent and achieve better lightweight performance. The biomaterials used by Ford is a different route. Not only are the materials environmentally friendly, but some materials can effectively reduce weight. It is indeed a new path. However, Ford's promotion of biomaterials is not in place, and it is also possible that the current domestic Ford does not use it. Same technology. In the future, there will be those outstanding lightweight technologies, let us wait and see. (Source: 58 cars)