As of June 2020, China has opened 86 main railway lines with a length of 37,000 kilometers. There are 3665 trains operating online, and both the operating mileage and the number of trains account for 2/3 of the world.
According to the plan of the China National Railway Administration, by 2030, the railway mileage will reach 45,000 kilometers and 7,000 trains will be put into use. In the field of intercity rail transit, as of the end of 2019, 40 cities in China had opened 208 subway lines with a mileage of 6,736 kilometers and the number of trains reached 6,966. "It is estimated that a total of 7,800 kilometers will be built by 2025, and the number of trains will exceed 16,000 by then. This will bring huge market demand for carbon fiber composite materials."
At the "2020 China Smart Rail Transit Industry Summit" co-sponsored by Qingdao Metro Group Co., Ltd., Smart Rail Transit Industry Observation, China Technical Market Association Rail Transit Professional Committee, and National Advanced Rail Transit Equipment Innovation Center, CRRC Qingdao Sifang Locomotive Gao Yulong, Director of Composites R&D Department of Vehicle Co., Ltd., shared the application of carbon fiber composites in rail transit.
Gao Yulong said that there are currently 3,800 high-speed trains in China. If the utilization rate of carbon fiber and other composite materials reaches 30%, it will generate a demand of 300,000 to 500,000 tons. If it is extended to areas such as urban rail and freight transport, the demand will exceed 1 million tons. . "If it goes well, the use of carbon fiber composite materials in rail transit trains can expect a market scale of 30,000 to 50,000 tons/year."
Application experience matures
It is understood that since the 1950s, carbon fiber composite materials have been used in cutting-edge fields such as aviation and aerospace for their unique properties such as light weight, high strength, fatigue resistance, and strong designability. With the continuous improvement of the performance of carbon fiber composite materials And the cost reduction has been widely used in the fields of automobiles, ships, wind power and other fields. The rail transit vehicles draw on the application results of different fields, and have made a lot of attempts from the secondary load-bearing parts to the main load-bearing parts, and accumulated rich experience.
The application of carbon fiber composite materials in rail transit trains in China is relatively late, but it has developed rapidly. A large number of research and development attempts have been made in different application fields such as locomotives, passenger cars, freight cars, high-speed trains, intercity and urban rail, and accumulated rich experience.
He said that carbon fiber composite materials have gradually become a system solution. For example, in terms of lightweight, the overall molding of the train hood reduces the weight by 20%; the overall molding of the windshield plate reduces the weight by 40%; the overall molding of the cab reduces the weight by 35 %; The console mold is formed to reduce the weight by 30%; the equipment compartment is reduced by 35%; the skirt is integrally formed, and the weight is reduced by 30%.
At present, the application of carbon fiber composite materials is gradually developing toward the main structure. He said that the main structure of the next-generation subway driver's cab, car body, frame and equipment compartment at a speed of 140 kilometers per hour is exploring the design process of large-scale carbon fiber composite materials. Prepare technical reserves for the migration of the main structure to carbon fiber composite materials, and the application assessment has been completed.
"Carbon fiber composite materials are gradually developing into the field of high-speed trains." He said that carbon fiber composite materials are used in high-speed rail modular structures, which can be single-piece, modular and integrally disassembled to form a pull-out bottom plate and a folding skirt. Easy to assemble and maintain. As a result, compared with the traditional aluminum alloy, the weight is reduced by 35%, and it can withstand vibration and shock, high temperature, high humidity, wind, sand, rain and snow erosion.
At the scene, he introduced the development status of carbon fiber composite materials in the field of high-speed trains.
Breakthrough and challenge
Gao Yulong analyzed the current technological breakthroughs in the application of carbon fiber composite materials in rail transit trains.
He said that after the R&D and process optimization of the fourth-generation equipment cabin, the application cost of carbon fiber composite materials has reached 1.5 times that of aluminum alloys, and it has reduced weight by 30%. "Driven by mass production, it can achieve the same cost as aluminum alloy."
In terms of material selection, we explored fabrics, prepregs, core materials, and adhesive systems suitable for rail vehicles that meet the technical requirements of low cost, medium strength, medium temperature, weather resistance, and impact resistance; in terms of resin systems, we explored the flame retardancy of different resins. Various flame-retardant solutions such as modification methods and surface fire-retardant films have solved the fire-proof problem of the equipment compartment, and found out a fire-resistant solution suitable for the structure of rail vehicles.
In terms of inspection and verification, it has passed the verification requirements of equipment cabin frame and module strength test, modal test, fire test, impact test, and non-destructive testing.
"In the future, we need to fully explore the characteristics of composite materials, further optimize the structure, explore efficient and automated production processes, and improve product production efficiency and yield."
Finally, he analyzed the challenges faced by the application of carbon fiber composite materials.
"Form a one-stop lightweight solution based on TQC control for carbon fiber composite material selection, structural design, simulation optimization, test verification, manufacturing inspection, maintenance, recycling, etc. in the rail transit field, and achieve the goal of engineering migration. Facing daunting challenges."