A serious traffic accident occurred in Yiwu recently. A video posted online shows a Nio ES8 crashing into a road pillar at a fork in the road, severely damaging the vehicle, which broke apart and caught fire. Rumors say the vehicle was traveling at 150 km/h.
Yiwu Public Security Bureau issued a warning that on August 1st at 1:48 pm, a traffic accident occurred at Lingyun overpass section of the airport road. After investigation, the driver of the vehicle, Shen, drove a small ordinary passenger car through the intersection of the west ring road and the auxiliary road of the airport road when it hit a road post, causing the vehicle toYiwu Public Security Bureau issued a warning that on August 1st at 1:48 pm, a traffic accident occurred at Lingyun overpass section of the airport road. After investigation, the driver of the vehicle, Shen, drove a small ordinary passenger car through the intersection of the west ring road and the auxiliary road of the airport road when it hit a road post, causing the vehicle to catch fire. At present, the driver Shen died after rescue failure, there were no other people in the car, and the cause of the accident is under further investigation.
All-aluminum enhanced, NIO ES8 safety is questioned?
It is understood that the new ES8 adopts an all-aluminum body structure, with an aluminum alloy content of 90.5% and 39,400 Nm/Deg, far exceeding the industry standard of 22000Nm/deg.
Looking back on the birth of the ES8, Roger Mulkusson, vice president of NIO Vehicle Engineering, said: "On the first day, we decided to use an all-aluminum body. Because we believe that lightweight will be the future trend of electric vehicles, because it is lighter, stronger and more environmentally friendly."
Traditional car manufacturers have been using aluminum body structures, but there are few mass-produced cars that use 100% aluminum components like Nio's, so Nio has been questioned about the safety of its body.
Public data shows that at the beginning of the birth of ES8, the use rate of aluminum is as high as 96.4%, which is the highest proportion of aluminum application in the global mass production of all-aluminum body. In order to ensure the strength of the vehicle, ES8 white body comprehensively uses 3 series, 5 series, 6 series and 7 series aluminum. Among them, the 3 series alloy is vacuum high pressure die casting aluminum alloy, which has the characteristics of high strength, high dimensional accuracy, good fluidity in the casting process and heat treatment strengthening, which can form complex structures and promote lightweight design; the 5 series aluminum belongs to relatively mature plastic aluminum alloy, which is widely used in the door cover opening and closing parts and body outer covering parts; the 6 series plate material has high strength, can be baked strengthening, and gives consideration to molding and performance, which is the main material of the body skeleton; in addition, extruded aluminum alloy (extruded profile) is mainly the 6 series, which has high strength, excellent impact toughness and energy absorption performance, and has been used in military equipment, armor plate and missile device.
Zhang Kang Kang, a famous automobile blogger and doctor of automobile department of Tsinghua University, once said that "the crash safety of all-aluminum structure is definitely poor" is unscientific; "the strength of steel-aluminum mixed body is definitely higher than that of all-aluminum structure", is also unscientific. The design concept that can best reflect the technical level and bring the most value should be "the right material applied to the right place".
However, although the Nio ES8 received a five-star safety rating from the European New Car Safety Assessment Programme (Euro NCAP) in 2021, its overall score was below 90%, and there are still questions about the Nio ES8's collision results due to the lack of full coverage of the side airbags and poor head protection.
150,000 have all aluminum body, aluminum for steel is good?
Before Jaguar XJ, Land Rover Range Rover, Audi A8, and after NIO ES8, BMW 5 series all adopted the all-aluminum body design, so the impression of Before Jaguar XJ, Land Rover Range Rover, Audi A8, and after NIO ES8, BMW 5 series all adopted the all-aluminum body design, so the impression of aluminum body has always been the exclusive of luxury and high-end models.
But from this year, more and more civilian class models, especially new energy vehicles, prefer aluminum body, such as Xpeng G6, Tesla Model Y aluminum die-casting body, and Chery recently released the first domestic aluminum-based lightweight platform S5X, the all-aluminum body technology to the 150,000 yuan level of Chery eQ7, so that we thoroughly feel the lightweight aluminum body is no longer so far away.
So is aluminum a good or bad choice for a car body? Will "all aluminum" be the trend of the future?
All-aluminum body is not "all-aluminum" material
Many people will understand the body of the car is made of aluminum alloy material, inMany people will understand the body of the car is made of aluminum alloy material, in fact, the "body" in the body of the car mainly refers to the body weight frame main structure, also known as the "white body", and the "all aluminum" in the body of the car refers to the main material of the white body is aluminum alloy, some important structures that affect the safety of the collision in the white body will still use high strength hot forming steel.
That is to say, the all-aluminum body is actually a steel-aluminum composite body, 100% aluminum alloy made of all-aluminum body in the mass production of the car does not exist.
For example, the first domestically produced Jaguar XFL, which was famous for its all-aluminum body, only applied 75% of aluminum to its body. These RC5754 high-strength aluminum alloys developed by Nobelis were mainly applied to many body structural parts of Jaguar XFL.
For example, AC600 aluminum alloy is applied to body reinforcement, AC300 aluminum alloy is applied to crash beam structure, AC170 aluminum alloy is applied to outer plate banding and side coveringFor example, AC600 aluminum alloy is applied to body reinforcement, AC300 aluminum alloy is applied to crash beam structure, AC170 aluminum alloy is applied to outer plate banding and side covering parts.
Another aluminum car body in the world's mass production of aluminum application ratio is the highest is NIO ES8, the body aluminum use rate is only as high as 96.4%, but this still makes the ES8 such a huge body size, the body weight is only 335 kg.
Aluminum body has obvious advantages
Aluminum body has many advantages, one of which is well-known is lightweight. As the saying goes, "a white hides a hundred ugly, a heavy destroy all", in the car to increase a horsepower is often less than a kilogram of weight, lightweight for modern automotive importance is self-evident, lighter body means lower energy consumption, better acceleration, handling and braking performance.
And the use of aluminum alloy is undoubtedly one of the most effective means of weight reduction of vehicles at present.
Data show that using aluminum instead of traditional steel can reduce the weight of the whole car by 30-40%; using aluminum to manufacture the engine can reduce the weight by 30%; aluminum radiator is 20% to 40% lighter than the same copper products.
For example, the fourth-generation Range Rover adopted an all-aluminum body, which successfully achieved a weight loss of nearly 200 kilograms. The Ford F-150 adopted an all-aluminum body, which reduced the weight of more than 300 kilograms. The Chery eQ7 adopted an all-aluminum body, which also achieved a weight loss of 30%. Obviously, the weight loss effect of replacing steel with aluminum is significant.
Secondly, the all-aluminum body also has the characteristic of corrosion resistance.
You should know that aluminum products will quickly form a dense oxide film on the surface after contacting with air. Although the thickness of this film is only 100,000th of a centimeter, it is very tough and stable, which can prevent the inner aluminum from being eroded.
So aluminum body is generally more corrosion resistant, in addition to the body life is longer, but also save the process cost.
In addition, aluminum body will have some advantages in structural strength. Although the strength of aluminum alloy is not as high as that of high-strength steel under the same structure, it can still improve the stiffness of the body while ensuring lightweight through reasonable structural design.
There are calculation data showingThere are calculation data showing that the thickness ratio of steel and aluminum alloy with the same strength is 1:1.4, while the weight ratio is only 1:0.5. In simple terms, under the same strength, aluminum alloy is half lighter than steel.
At the same time, the collapse energy absorption performance of aluminum alloy material is better, which can be used for the collapse area of the front and rear anti-collision beams of the car body to absorb energy better, buffer impact, so as to ensure the "soft landing" of the occupant cabin and reduce collision damage.
Aluminum Bodywork Has Its Drawbacks
Everything has two sides, and the all-aluminum body is no exception.
Firstly, the manufacturing process is a problem. In a word, it is difficult to process and costly.
Because for the steel and aluminum these two different materials splice, using traditional welding technology its difficulty will be very big, and the welding strength is difficult to guarantee.
In addition, the toughness of aluminum plate is poor, which is generally difficult to stamp. The stamping forming of aluminum plate requires higher precision of equipment and process compared with steel plate.
So to make a steel-aluminum body, more stitching processes, such as riveting and gluing, will be developed, which is much more complex than traditional vehicles and will increase manufacturing costs.
Then there is the strength problem. No matter what process is used, under the same structure, the all-aluminum body is still not superior to the body supported by hot-formed steel in terms of rigidity and guarantee of the integrity of the passenger compartment.
As global automotive safety systems become increasingly stringent, many models have had to abandon all-aluminum body designs.
For example, the Audi A8, the third generation body from all aluminum into a steel content of 8%, and then to the fourth generation body, the steel content has been increased to 40%.
Finally, the maintenance problem, aluminum ductility is very poor, once the accident, aluminum body covering parts is difficult to repair sheet metal, and if encountered a larger collision accident, it can only be replaced, the maintenance costs may be close to the price of a new car.
In general, although the cost of aluminum body and late maintenance is still a problem, but under the same conditions it can bring the vehicle's high safety, high control, low energy consumption and corrosion resistance has proved its value. Of course, aluminum is not perfect in the car, now we have higher and higher requirements for the safety of the car, after all, no matter how exquisite the appearance, how high-tech interior, still can not hide the safety or one of the most important factors in car purchase.