Carbon Fiber Pultruded Composites: Innovation and Prospects for Cross-Field Applications

 

Carbon fiber pultruded composites have been widely used in wind turbine blades, automobile manufacturing, drones, rail transit and construction. In wind turbine blade manufacturing, the use of carbon fiber main beams has modulus advantages and lightweight characteristics, and the pultruded carbon plate stacking infusion process provides high fiber volume content and excellent mechanical properties. In the field of automobile manufacturing, carbon fiber pultrusion technology achieves lightweight parts and improves safety and fuel economy.

 

In the field of drones, carbon fiber pultruded pipes show excellent mechanical properties. In the field of rail transit and construction, carbon fiber pultruded profiles provide new structural design possibilities through lightweight and strength advantages. Emerging technologies such as large tow carbon fiber pultrusion and carbon fiber reinforced thermoplastic pultrusion have brought new opportunities for improving the performance of composite materials and expanding their application areas. These advances have painted an attractive picture for the future development of carbon fiber pultruded composites.

 

 

1. Application of Carbon Fiber Pultruded Composite Materials

 

Wind Turbine Blades

As wind turbines continue to grow in size, the length and weight of blades are increasing rapidly. Recently, Dongfang Electric has successfully developed and launched the world’s longest 126-meter ultra-long blade. In this context, the necessity of using carbon fiber main beams as large blades is highlighted:

 

1. The modulus growth of glass fiber materials is close to the limit, while the modulus of carbon fiber is 3-8 times higher than that of glass fiber.

 

2. The specific gravity of carbon fiber is about 30% lower than that of glass fiber.

 

 

Carbon Fiber Pultrusion Process (Second from Left) has Comprehensive Performance Advantages

 

The wide application of carbon fiber pultrusion process in the field of wind turbine blades has been recognized by the industry as a whole. Blade manufacturers such as Sinoma Technology, Times New Materials, Zhongfu Lianzhong, and Ailang Technology, as well as companies such as Sany Heavy Energy, Mingyang Electric, and Shanghai Electric have released blades using carbon fiber or carbon-glass hybrid pultruded beams.

The carbon fiber pultrusion carbon plate lamination infusion process developed by Vestas uses an efficient pultrusion molding process to prepare carbon fiber into unidirectional carbon fiber sheets, and arrange them in layers, and then infuse them with resin and solidify them into wind turbine blade main beams.

 

Compared with traditional vacuum infusion and prepreg processes, the pultruded carbon plate lamination infusion process has a higher fiber volume content and better fiber arrangement, resulting in excellent mechanical properties. The pultrusion process itself is a continuous automated process, which makes the quality of carbon plates more consistent, production efficiency higher, and manufacturing volume larger. In addition, the production length of pultruded carbon plates is not limited, and large-length carbon plates can be cut to the length required by the end user.

 

UAV

 

 

The application of carbon fiber pultruded composites in the field of drones is mainly reflected in the manufacture of pultruded carbon fiber tubes. Pultruded carbon fiber tubes have excellent mechanical properties such as stiffness, durability and lightness in building the structural frame of drones, and are very suitable for manufacturing drone parts. Due to the characteristics of the pultrusion process, the resulting tubes are consistent in performance, behavior and quality, which is crucial for manufacturing drones with reliable performance.

 

Automobile Lightweight

 

 

Chassis Made of Carbon Fiber Reinforced Plastic parts is 60% lighter than comparable steel structures

 

The carbon fiber pultrusion process is an economical way to produce parts that replace extruded steel and aluminum. Although the technology is currently only suitable for “straight parts”, it has already been used in some automotive fields. Zoltek in the United States has developed pultruded door sills/rocker panels and door intrusion beams, while Daimler and Secartechnologie won awards in 2016 for the use of pultruded carbon fiber reinforced pillars in the Mercedes C-Class Cabriolet and S-Class. Krauss-Maffei’s iPul technology in Germany produces carbon fiber pultruded profile parts and can be produced at a speed of 2.25 meters per minute under a pulling force of 20 tons. The advantage of pultruded carbon fiber is that composite parts with optimized functions and costs can now be produced economically on a larger scale. This technology has been put into practical use on today’s roads and has a wide range of potential applications.

 

Rail Transportation

 

The introduction of pultruded profiles has injected new vitality into the rail transportation field. Through precise manufacturing processes, carbon fiber pultruded profiles can not only meet the stringent requirements of rail transit projects for structural strength and durability, but also reduce vehicle weight and improve operating efficiency. Its excellent tensile and compressive properties make it play a vital role in the structural components of rail transit systems, laying a solid foundation for the sustainable development of modern urban rail transit systems. The carbon fiber pultruded profiles of CG RAIL in Germany combine multi-cavity sections with a wall thickness of up to 26mm, and adopt unidirectional fibers and textile reinforcement.

 

2. Technical Trends

 

Large Tow Carbon Fiber Pultrusion Composite Material Process

 

Large Tow Carbon Fiber Pultrusion Composite Material Process is an efficient and environmentally friendly composite material preparation technology. It bundles large-sized carbon fibers into a bundle, injects resin during the stretching process, and then undergoes multiple processes such as curing and subsequent processing to finally obtain a composite material with excellent performance. The main raw materials include carbon fiber, resin and additives. Carbon fiber is used as a reinforcing material for composite materials. Its selection should take into account factors such as mechanical properties, surface state and price. Large tows of carbon fiber with a diameter of 10-13μm and a length of more than 40mm are usually used. The resin plays a bonding and filling role. Different types of resins are selected according to specific needs, such as epoxy resin and phenolic resin. The use of additives can improve the curing performance and processing fluidity of the resin. Large-tow carbon fiber pultruded composite materials have the characteristics of high performance, good surface quality and environmental sustainability.

 

Bending Pultrusion Process

In the bending pultrusion process, Liu Tianqiao, Feng Peng and others combined the latest technology and proposed a bending pultruded arch beam, which gave the pultruded profile beam member a certain pre-arch to offset the vertical deflection. At the same time, the cross-section of the pultruded profile was optimized, and the premature failure of the member due to buckling was successfully avoided. The bending pultruded arch beam can be directly designed using the design method of traditional straight components, which has obvious advantages. On this basis, a 20-meter-long covered bridge has been built, located in Beijing MCC Construction Research Institute. The bridge meets the design requirements in terms of strength, deflection and vibration. Especially under the condition of end fixation, a certain axial force will be generated in the beam, which makes the bridge have a shallow arch force mode, further increasing the stiffness of the structure. The use of curved pultruded arch beams can further improve the mechanical properties of pultruded profiles and expand the application scope of composite materials in the field of civil engineering.

 

Carbon Fiber Reinforced Thermoplastic Pultrusion Process

In the carbon fiber thermoplastic pultrusion process, thermoplastic resin becomes plastic under high temperature conditions, and carbon fibers are evenly distributed in it, forming a high-strength and rigid composite material structure. This process has been widely used in aerospace, automobile manufacturing, building structures and other fields. In the aerospace field, the lightweight and high-strength characteristics of carbon fiber thermoplastic pultrusion products help improve aircraft fuel efficiency and reduce overall weight. In automobile manufacturing, the parts manufactured by this process can not only reduce the weight of the vehicle, but also improve the safety and fuel economy of the vehicle. In the field of construction, the carbon fiber thermoplastic pultrusion process can produce lightweight but strong structural materials, improving the durability and wind resistance of buildings.