Research on the Development of Lightweight Automobiles in China in the Past 5 Years

Lightweight vehicles have become an important development trend for energy conservation and emission reduction, especially in the past five years. With the rapid growth of car ownership, China, as the largest country in the production and sales of cars, is increasingly short of petrochemical products, and the total CO2 emissions continue to increase. Clean energy has not yet been fully popularized, and it is more urgent and important to solve the problem of reducing the weight of automobiles. The lightweight of automobiles is a systematic project. We cannot simply consider reducing the curb weight of the car. We must innovate in advanced design concepts, advanced materials, advanced manufacturing technologies, and advanced assembly processes to ensure safety, improve performance, and increase comfort while reducing weights.
 
In the 21st century, the automobile manufacturing industry shows the development trend of electrification, interconnection, intelligence and sharing. Under this background, the lightweight  of automobiles is one of the important strategic measures to realize the four modernizations of automobiles, including the implementation of strategic measures for the development of various system modularization and integration for automobile lightweight. The lightweight of automobiles is that under the premise of ensuring the strength and safety performance of the automobile, reduce the curb weight, thereby improving the power of the automobile, and achieving the purpose of energy-saving and emission reduction. According to data from the Alcoa Association, a 10% reduction in a vehicle's weight can reduce fuel consumption by 3.3%, and a 10% reduction in diesel vehicles' weight can reduce fuel consumption by 3.9%. Lightweight cars are conducive to active safety, can effectively increase operational stability, shorten braking distance and reduce weight by 10%. The braking length can be reduced by 5%, and the steering force can be reduced by 6%. The automobile manufacturing industry is a pillar industry of the national economy. China is the largest country in the production and sales of automobiles. With the emergence of energy shortages and environmental pollution, automobile lightweight becomes more important.
 
In the past five years, automobile lightweight is mainly reflected in meeting the performance of automobile products and necessary cost control. Through computer hardware and software, big data and lightweight design done by cloud computing, lightweight materials and technologies are used to obtain energy saving and emission reduction under good performance of automotive products.
 
1. Automobile lightweight technology improving day by day
1.1 Three ways to realize lightweight automobiles 
The realization of lightweight automobiles includes lightweight material applications, lightweight structural design, and lightweight manufacturing processes. The lightweight development in each field has evolved into the support of multiple technologies. In recent years, the evolution rate is accelerating.
 
1.2 Significant changes taking place in the design concepts and design methods of lightweight optimization
Regardless of the lightweight without good performance, it is difficult to be convincing. It's difficult to have a breakthrough for traditional design and structural optimization design concepts based on previous generation models. In this case, CAD, CAM or CAE integrated technology is applied and SFE CONCEPT parameterized design software is used to establish the corresponding 3D model and finite element model; innovate design, calculation and testing methods, relying on big data, cloud computing and Internet creation platform. Carry out corresponding analysis and simulation instead of real vehicle tests; pay attention to systematization, modularization, integration and integrated design. Comprehensively consider the structure, size optimization, static and dynamic characteristics of the car, considering the mixing of multiple materials, gradual thickness and hollow design according to the performance requirements for mechanical structure, improving the rigidity of the vehicle, reducing the weight, compressing the space, optimizing the development process and shortening the development cycle. It can be seen that automobile lightweight needs to do a good job in five aspects in the integration of structural modularization, lightweight of connection modes, lightweight finite element aided design, lightweight systems, and lightweight materials. At present, lightweight optimization design has become multi-disciplinary, multi-objective, multi-condition optimization design.
 
1.3 The lightweight technology of automobiles becoming a hot topic in the world's automotive scientific and technological innovation research
The lightweight technology of automobiles mainly includes lightweight structure optimization technology, manufacturing process technology and material technology. The innovation of lightweight structure optimization technology is the most active. The research, development and application of lightweight materials and the new manufacturing and processing technology and assembly technology that adapt to new materials have also achieved extraordinary results. At the same time, technologies such as environmentally friendly recycling and reuse of materials have also been launched. According to statistics, the total number of domestic patents related to structural optimization technology in 2016 was 2636, which has an increase of 686, compared with 1950 patents in 2015. The number of patents related to lightweight structure optimization was 1669, accounting for 63% of the 3 types of lightweight technology patents that year. There are 218 and 290 patents related to lightweight material technology and manufacturing process technology. The number of automotive scientific research personnel, scientific research projects, total funding for scientific research, and science and technology achievement awards have created a new record. In 2016, BYD and Hefei University of Technology have led domestic automobile patents. Since 2016, China's lightweight engines have continued to innovate. The weight of the high-quality 4N20 series engine is 10% lower than that of the previous generation. Power batteries are the core of new energy vehicles. The main innovations in battery materials include positive and negative materials, diaphragm materials, and electrolytes, which have made great progress. Nowadays, the energy consumption, lightweight, and intelligence of pure electric passenger vehicles are at the upper level in the world. The research on fuel cell quality hydrogen storage rates and volume hydrogen storage rates has made great progress.