Will cars become less safe after being lightweight? Safety and lightweight can be improved together

One of the development directions of the automobile industry today is lightweighting. The so-called lightweighting refers to reducing the weight of the car body by selecting different materials and different processing methods during the automobile manufacturing process, making the car body as light as possible.

Automotive lightweight materials are divided into two categories: metal and non-metal. Metal materials mainly include high-strength steel, aluminum alloy, magnesium alloy, etc. Non-metal materials include engineering plastics and composite materials. Among them, aluminum alloy materials have many advantages. Its density is 1/3 of that of steel. It has good ductility, corrosion resistance, and is easy to recycle. Moreover, it has good castability and can be processed into different shapes. It is one of the most popular lightweight materials at present.

Lightweighting has three major advantages: fuel saving, emission reduction, and improved driving experience. Tests show that if the weight of the vehicle is reduced by 10%, fuel efficiency can be improved by 6%-8%; for every 100 kg reduction in the curb weight of the vehicle, fuel consumption can be reduced by 0.3-0.6 liters per 100 kilometers; and for every 100 kg reduction in the weight of the vehicle, fuel consumption can be reduced by 0.7%. For every 100 kg reduction in the vehicle, carbon dioxide emissions can be reduced by about 5 grams per kilometer. In terms of driving, the acceleration performance of the vehicle will also be improved after it is lightweight, and the braking distance will also be reduced due to the small inertia in the event of a collision.

The cost of lightweight materials such as aluminum alloy is relatively high, but the cost will gradually decrease with the scale and maturity of technology in the future. The main problem of aluminum alloy is the repair after the collision. For steel car body, a small collision deformation can be directly restored to its original shape by knocking. However, aluminum alloy has very poor formability at room temperature, knocking will only damage the parts, and heating cannot guarantee the strength after cooling. Therefore, after collision deformation, the whole part often needs to be replaced, which is troublesome and expensive.

Theoretically, the lighter the car is, the smaller its inertia is. When the car brakes at the same initial speed, the less energy the brake consumes, the faster the braking deceleration is, the shorter the braking distance is, and the better the active safety of the car is. When a car collides, the impact energy is proportional to the mass of the car. Therefore, under the same conditions, the lighter the car is, the smaller the impact energy is during a collision, the smaller the deformation of the body structure, the amount of intrusion, and the impact acceleration of the occupants are, and the better and safer the car is for the occupants.

Lightweighting of cars can reduce the weight of the car while maintaining the original driving safety, crash resistance, shock resistance, comfort and other functions, and without increasing the cost of the car itself. Lightweighting does not mean reducing the safety and performance of the car. On the contrary, design optimization and manufacturing process improvement will help improve safety, and the lightweight materials used are better in rigidity and strength. Therefore, the smaller the deformation of the car during a collision, the better the protection effect on the occupants.

With the continuous development of materials science and mechanical engineering, the materials used in automobiles no longer need to simply increase the thickness and quantity of steel plates to improve safety performance. Through the application of new materials, continuous optimization of structural design and the interconnection of different materials, it is possible to maintain light weight without sacrificing safety performance.

Nowadays, more and more active and passive safety technologies are being used in vehicles. As a result, the trend of automobile development is bound to be safer and safer. Although materials are still the main factor in safety, they are no longer the only guarantee of safety.

At present, the active safety of automobiles has been supported by various technological configurations, such as pre-collision braking, radar ultrasonic assisted driving, and ACC adaptive cruise control.

In terms of passive safety, when a collision is inevitable, the safety of a car should be understood as how to minimize the energy of the collision from being transferred to the driver.

Energy changes are nothing more than conversion and transmission. Under the condition of protecting the integrity of the crew cabin and minimizing deformation, the correct design concept is to disperse the energy of the impact to various energy-absorbing areas of the vehicle body through the energy-absorbing structure, allowing different parts to absorb the energy, decompose and absorb it in the form of deformation and fragmentation, and thus reduce the physical damage caused by the collision energy to the crew. Compared with the use of multiple materials, the manufacturer's mastery and application of structural mechanics and material science is more critical.

As a winner of Toutiao's Qingyun Plan and Baijiahao's Bai+ Plan, the 2019 Baidu Digital Author of the Year, the Baijiahao's Most Popular Author in the Technology Field, the 2019 Sogou Technology and Culture Author, and the 2021 Baijiahao Quarterly Influential Creator, he has won many awards, including the 2013 Sohu Best Industry Media Person, the 2015 China New Media Entrepreneurship Competition Beijing Third Place, the 2015 Guangmang Experience Award, the 2015 China New Media Entrepreneurship Competition Finals Third Place, and the 2018 Baidu Dynamic Annual Powerful Celebrity.