Application of composite materials in the field of UAV drones
Due to differences in application fields and usage purposes, there are significant differences between unmanned aerial vehicles and conventional carrier aircraft in terms of manufacturing materials and body structures. When designing a carrier aircraft, the first consideration should be the human carrying factor, and there are corresponding standards and requirements for the safety of the aircraft structure and material load-bearing. However, drones do not need to consider human safety performance issues and can have more attempts and choices in body structure design and manufacturing materials. Composite materials have better performance in terms of stiffness, strength, seismic and fatigue resistance, and thermal expansion coefficient, and are therefore the preferred materials for unmanned aerial vehicle manufacturing.
(1) Application parts of composite materials for unmanned aerial vehicles
- Structural components: The main structure, wings, tail fins, and other parts of the drone can be made of composite materials. Composite materials have lightweight, high strength, good fatigue resistance, and impact resistance, making unmanned aerial vehicles have a longer service life and better flight performance.
- Motor compartment: The core components of unmanned aerial vehicles, such as motors, controllers, etc., can also be protected using composite materials. Composite materials can provide good electromagnetic shielding performance, effectively reduce electromagnetic interference, and ensure the stable operation of unmanned aerial vehicle electrical systems.
- Heat dissipation material: Drones generate a large amount of heat during flight, and composite materials can be used to make heat dissipation fins to help drones effectively dissipate heat and ensure the normal operation of equipment.
- Fuel system: The application of composite materials in unmanned aerial vehicle fuel systems is becoming increasingly important. For example, composite hydrogen storage tanks can be used to store hydrogen gas as a power source for drones.
- Sensor casing: Drones need to be equipped with various sensors, such as GPS, barometer, gyroscope, etc. Composite materials can be used to create lightweight and high-strength shells, protecting sensors from external environmental influences and ensuring their accuracy and stability.
(2) Analysis of Manufacturing Process for Composite Components of Drones
- Hot press molding process
The hot press molding process can make the internal and external quality of composite components for unmanned aerial vehicles lightweight and excellent, with uniform resin content and excellent mechanical properties. Therefore, it has become the preferred process for manufacturing composite components for the main load-bearing components and high-speed requirements of unmanned aerial vehicles. The drawback of the hot press molding process is its poor economic efficiency, which is mainly reflected in its high requirements for manufacturing equipment, initial investment, and processing costs, which also to some extent restricts the popularization of this technology. Therefore, due to considerations of economic benefits, low-temperature and low-pressure molding technology is often easily replaced in the actual manufacturing process of drones.
- Vacuum bag forming process
The advantages of vacuum bag forming technology are high cost-effectiveness, achieving ideal manufacturing results with minimal cost investment, and low difficulty in process operation, making it easier to popularize and implement. Its drawback is that the molding pressure is relatively small, so the implementation targets are mostly composite material components with relatively low quality standard requirements. From the perspective of application scope, vacuum bag forming technology is relatively common in the manufacturing of composite materials for small low-speed unmanned aerial vehicles. From the perspective of operation methods, the preliminary operations of vacuum bag forming technology mainly include two methods: pre impregnated material laying and wet laying. From the perspective of operational effectiveness, the adhesive coating of composite components under the pre impregnated material laying process is uniform, with good stability and quality.
- Compression molding process
The advantages of the compression molding process are high production efficiency, easy operation, good economy, high molding pressure, and the ability to balance the cost input and quality output of drone manufacturing. In terms of the scope of application, the molding process is mostly used in the manufacturing of composite components of UAV foam sandwich structure. From the perspective of operation process, the molding process is divided into two steps: ① foam core production and skin paving, ② molding, pressing and curing. From the implementation effect, the use of this process in the composite material components of drone wing panels has significantly improved the aesthetics and accuracy of drone wings. In addition, attention should be paid to the reasonable selection of the compression machine to ensure the optimal effect of the compression molding process.
- Low temperature forming technology
The advantages of low-temperature molding technology are relatively low process cost and controllable energy consumption. It can cure low-temperature polymer resin into shape at 60-80 degree, making it an effective supplement to the current hot press molding process. From the perspective of applicability, low-temperature forming technology not only has strong dimensional tolerance for composite components, but also can directly cure and form composite materials at room temperature and pressure. Therefore, it is widely used in various types of drones. From the perspective of operational effectiveness, compared with high-temperature forming technology products, low-temperature forming technology can significantly reduce the manufacturing cost of unmanned aerial vehicles while ensuring excellent quality of composite components. In addition, in order to achieve good results in low-temperature molding technology, it is necessary to pay attention to the continuous improvement of resin and low-temperature molding prepreg.
(3) Proportion of composite materials for UAV
The main structure and wing components of drones are usually made of lightweight, high-strength materials such as composite materials, aluminum alloys, etc. These materials are relatively expensive, but lightweight, which is beneficial for improving the flight performance of drones. The proportion of structural materials in the cost of drones is about 20% -30%,
The weight proportion of composite materials in drone structures varies depending on the type, size, and application scenario of the drone. Generally speaking, the weight proportion of composite materials in drone structures can reach 50% or even higher. Here is a rough estimate:
Small unmanned aerial vehicles: For small unmanned aerial vehicles, the proportion of composite materials used is relatively high, which can reach 70% -80% of the body weight. This is because small drones often use lightweight materials to improve flight performance, while composite materials have high strength and stiffness, which can meet the structural requirements of small drones.
Medium sized drones: The proportion of structural materials in medium-sized drones is relatively low, with composite materials accounting for about 50% -60% of the weight. This is because medium-sized drones may need to carry more loads, such as fuel, sensors, and payloads, so the selection of structural materials focuses more on the balance between performance and weight.
Large unmanned aerial vehicles: The weight proportion of composite materials in the structure of large unmanned aerial vehicles may be relatively low, about 30% -40%. This is because large unmanned aerial vehicles mainly use heavy structural materials such as aluminum alloys, titanium alloys, etc. to withstand greater loads and wind loads. In addition, large drones often have more space to accommodate fuel, equipment, and personnel, so the proportion of composite materials used is relatively low.