Undoubtedly, the lightweight has become the future trend of new energy vehicles.In October 2016, the National Power Strategic Advisory Committee, Tsinghua University professor Ouyang Minggao as the representative released the much-watched "energy-saving and new energy vehicle technology roadmap" , It is clear that the development of lightweight technology has risen to the national level.
Among them, the roadmap includes seven major directions of energy-saving vehicles, pure electric and hybrid vehicles, fuel cell vehicles, smart car and automobile manufacturing, power battery technology, and automobile manufacturing technologies including light-weight technologies, as shown in the following figure.
Relevant studies in the field of lightweight technology concluded that weight reduction directly implies an increase in cruising mileage.If the vehicle weight of a pure electric vehicle is reduced by 10 kg, the driving range may increase by 2.5 km and Professor Yang Yasheng of the Chinese Academy of Sciences interviewed Said that the same recognition of this conclusion, and added that to enhance the driving range of electric vehicles, in addition to strengthening the battery and drive system, and the extent of lightweight body is also inseparable, and lightweight body is the most obvious feature of the material Choose.At present, the light-weight materials used in new energy vehicles are mainly high-strength steel, aluminum, magnesium alloy, carbon fiber and other several.
Icon: Lightweight material selection
Next, Xiao Bian on the following characteristics of several lightweight materials and applications to sort out for your reference.
1, lightweight materials - high-strength steel
High-strength steels used in the field of new energy vehicles can be divided into conventional high-strength steel (ConventionalHSS) and advanced high-strength steel (AHSS) according to the strengthening mechanism. The advanced high-strength steels have better ductility, and at the same time meet the process performance Also has a higher potential for light weight.
Pictured: yield strength of high strength steel
At present, the international mainstream models of high-strength steel accounted for more than 70% of the body, of which independent brands of high-strength steel has reached 45% .It is understood that China is the most common high-strength steel applications in the country, the proportion of close to the body 50%, expected to be as high as 60-65% in the future. However, ultra-high-strength and advanced high-strength steels have lagged behind with only 5% of the current use rate and are expected to have 3 times more room for improvement in the future.
Pictured: High-strength steel body
Industry experts believe that high-strength steels have significant advantages over aluminum and magnesium alloys in terms of anti-collision performance, process technology and cost, meeting the dual needs of reducing vehicle mass and improving crash safety, even from a cost and performance point of view Look, is the best material to meet the lightweight body, improve collision safety.
2, lightweight materials - aluminum
The density of aluminum is only 1/3 of steel, thermal conductivity is more than 3 times higher than the iron.Most of the most noteworthy is that the structure of the aluminum steel can be optimized to achieve secondary weight loss, the effect can be directly reduced by 50% - 100%. Related studies have shown that the use of automotive 1kg aluminum weight can replace 2.25kg steel, weight loss up to 125%, the entire life cycle can reduce emissions 20kg. Thus, aluminum with its high strength, can be Circumstances, corrosion resistance, low density and other high-quality performance become the preferred material for car weight loss, the use of aluminum in the car will grow rapidly, automotive aluminum into the golden period.
The domestic car prices on the application of aluminum alloy, you have to mention Chery New Energy, the company introduced a new generation of pure electric mini-car - ants (codename eQ1), the structure of the use of the 'aluminum space structure + Composite outer cover 'combination of forms, a very good control of the body weight, reduce manufacturing costs and achieve a better lightweight body.
Icon: small ants
Icon: Aluminum frame + composite outer cover
However, the full aluminum body can not be underestimated, when the body by the collision damage, the aluminum alloy material is more difficult to shape, once improper operation, parts are likely to crack or even break, the general aluminum parts damaged, if the sheet metal Gold technology can not be adjusted, basically only the overall replacement.In addition, the aluminum alloy requires special technology to be welded.Therefore, the aluminum body means that the latter part of the maintenance costs may be higher.
As a pioneer of pure electric vehicles in the world, Tesla has long been exploring ways to reduce the weight of vehicles, and its iconic ModelS uses a large amount of aluminum alloy body and aluminum alloy components through special welding technology Links to steel components.
Icon: Tesla MODEL3 aluminum body
3, lightweight materials - magnesium alloy
Magnesium density is small, even 1/3 lighter than aluminum, its specific strength (tensile strength and density ratio) higher than the aluminum alloy, good thermal conductivity; In addition, magnesium alloy dimensional stability, easy to recycle, with good cutting Sexual, vibration damping performance is better.
Icon: pure electric magnesium alloy bus
Silver pure electric magnesium alloy bus is also equipped with active balancing technology BMS system of high-performance lithium-ion battery with high safety, high stability, fast charge, anti-attenuation ability and other characteristics, combined with magnesium alloy body and many other advantages, While providing passengers with a more low-carbon, environmentally friendly travel solutions, the reliability is better and the city travels safely.
As we all know, China's magnesium production accounts for about 75% of the world, so that new energy vehicles to achieve lightweight car body has brought convenience.China Automotive Engineering Society made a roadmap for energy saving and light weight is expected in the next 10 years, magnesium is used in High-end vehicles can break 100 kg / vehicle, above the common car to break through 20 kg / vehicle.
At present, there are a number of companies trial production of aluminum alloy body, more experts believe that the magnesium alloy body may become the mainstream of automotive lightweight body material.
4, lightweight materials - carbon fiber
Carbon fiber mechanical properties, less than the density of steel 1/4, but the tensile strength of steel 7-9 times, is the only one in 2000 ℃ above the high temperature inert environment does not reduce the strength of the material.
According to a research report released by a consulting firm in China, the demand for carbon fiber in China in the next few years will enter a period of rapid growth. It is estimated that the demand for domestic carbon fiber will reach 25,000 tons by 2020, an average annual growth rate of about 15.5%. The rise in demand in the industrial sector will be even more pronounced.
As one of the pioneers of lightweight vehicles, BMW's large-scale use of i3 and i8 production cars is the culmination of carbon fiber making the car .In 2015 the sixth generation of BMW 7 Series for the first time carbon fiber composite materials and Combination of steel, aluminum and plastic, making this generation of 7-body white body weight loss 40 kg.
A subsidiary of the Japanese Teijin Group has successfully developed a lightweight passenger car roof, the car roof made of carbon fiber reinforced plastic, aluminum and other light materials, will be used in Toyota developed the world's first batch of Mass production of fuel cell bus SORA.
Icon: Toyota fuel cell bus SORA
In fact, the current price of carbon fiber 1,500,1,600 yuan per kilogram, is a brittle material, once the force is too large will be directly broken, basically unable to repair after the damage, and high manufacturing costs and recycling costs make the current application of carbon fiber is still mostly limited In high-end sports car, sport utility vehicle and sports car.
Summary: This revolution in the automotive industry driven by new materials, new processes and new designs will also affect the global automotive industry pattern with the popularity of these models, especially at the present stage of the triumph of new energy vehicles , The quality of its complete vehicle has become one of the obstacles restricting its development, and the development of lightweight automobile can not be delayed.With the progress of lightweight materials technology, it will bring more possibilities for the development of new energy vehicles.
