Application of Composite Materials in The UAV Industry

Due to differences in application fields and intended use, UAVs (Unmanned Aerial Vehicles) differ significantly from conventional manned aircraft in terms of manufacturing materials and airframe structures. When designing manned aircraft, the primary consideration is human safety, which imposes strict standards and requirements on the structural framework and material load-bearing capacity. In contrast, UAVs do not need to account for passenger safety, allowing for greater flexibility in structural design and material selection. Composite materials, with their superior stiffness, strength, resistance to vibration and fatigue, and low thermal expansion coefficient, have become the preferred choice for UAV manufacturing.

(I) Application Areas of Composite Materials in UAVs

1. Structural Components: The main structure, wings, tail fins, and other components of UAVs can be manufactured using composite materials. These materials offer lightweight properties, high strength, excellent fatigue resistance, and impact resistance, enhancing the UAV's durability and flight performance.

2. Motor Housing: The core components of UAVs, such as motors and controllers, can also be protected using composite materials. These materials provide excellent electromagnetic shielding, effectively reducing interference and ensuring the stable operation of the UAV’s electrical systems.

3. Thermal Management Components: UAVs generate significant heat during flight. Composite materials can be used to manufacture heat dissipation components, ensuring effective thermal management and stable operation of the UAV.

4. Fuel System: Composite materials are increasingly used in UAV fuel systems. For example, composite hydrogen storage tanks can store hydrogen fuel, serving as an energy source for UAVs.

5. Sensor Housings: UAVs carry various sensors such as GPS, barometers, and gyroscopes. Composite materials can be used to manufacture lightweight, high-strength housings that protect these sensors from environmental factors, ensuring accuracy and stability.

(II) Manufacturing Processes of Composite UAV Components

1. Autoclave Molding ProcessThe autoclave molding process ensures lightweight, high-quality composite components with uniform resin content and superior mechanical properties. This process is preferred for manufacturing UAV load-bearing structures and high-speed components. However, its economic efficiency is relatively low due to high equipment requirements, significant initial investment, and high processing costs. As a result, low-temperature, low-pressure molding techniques are often used as an alternative in UAV manufacturing.

2. Vacuum Bag Molding ProcessThe vacuum bag molding process is cost-effective, requiring minimal investment while achieving desirable manufacturing results. Additionally, it is relatively easy to operate and widely applicable. However, the low molding pressure limits its use to composite components with lower quality requirements. This process is commonly used in small, low-speed UAVs. There are two primary methods: prepreg layup and wet layup. Prepreg layup results in a more uniform resin distribution, offering greater stability and quality.

3. Compression Molding ProcessThe compression molding process is efficient, easy to operate, and cost-effective while providing high molding pressure. This process balances cost and quality in UAV manufacturing and is particularly suitable for producing foam-core composite structures. The process involves two key steps: (1) foam core fabrication and skin lamination, and (2) mold pressing and curing. In UAV wing panel manufacturing, this process significantly enhances precision and aesthetics. Proper selection of the pressing machine is crucial to achieving optimal molding results.

4. Low-Temperature Molding TechnologyLow-temperature molding technology offers cost advantages and energy efficiency. This process can cure low-temperature polymer resin at 60–80°C, making it a viable supplement to autoclave molding. It supports a broad range of component sizes and allows direct curing at room temperature and atmospheric pressure, leading to widespread adoption in UAV manufacturing. Compared to high-temperature molding techniques, low-temperature molding reduces manufacturing costs while maintaining quality. To optimize results, continued improvements in resin formulations and low-temperature prepreg materials are essential.