The development of carbon fiber is an important material for the defense industry and the national economy. It belongs to technology-intensive key materials, and the carbon fiber industry is also a strategic emerging industry that the country has focused on. Carbon fiber composite materials have extremely high specific strength and specific rigidity, and are ideal materials for large-scale integrated structures. They have important application significance in military aircraft and military ships.
1.Carbon fiber superstructure
Composite materials have been used in the gunboat deckhouses of patrol gunships since the mid-1960s, and in the early 1970s, composite materials have also begun to be used in the superstructure of mine-hunting boats. The superstructure of the Royal Finnish rapid patrol boat Rauma also uses a composite sandwich structure, and the hull is made of aluminum alloy.
Compared with steel and aluminum, carbon fiber superstructures have many disadvantages, such as high manufacturing costs, because the connection with the steel deck is expensive. For medium frigates, the use of carbon fiber composite materials instead of steel in the superstructure will increase the construction cost by 50 % —150%. Nevertheless, many ship builders and navies have begun to accept higher manufacturing costs because they can save life cycle costs and reduce overall costs.
Carbon fiber propeller
The propeller materials of naval vessels have always been nickel-aluminum-copper alloys. There are many problems such as the high cost of machining complex blades, the blades are prone to fatigue and cracks, the acoustic damping is relatively poor, and noise is caused by vibration. So navy designers had to consider other materials, the most striking being stainless steel, titanium alloys, and carbon fiber.
The design and performance of carbon fiber propeller systems are highly confidential, and research progress in recent years has not been published. However, it is well known that the fibers in carbon fiber blades can withstand major hydrodynamic and centrifugal forces. At present, a large number of naval vessels are equipped with carbon fiber propellers, such as landing ships and minesweepers. In addition, carbon fiber propellers are also used in torpedoes and small ships.
3.Carbon fiber mast
Composite materials were first applied to masts in the 1960s. The traditional steel mast uses an open structure, which protrudes outside, which will interfere with the ship's radar and communication system and is prone to corrosion. The United States Navy began developing an advanced fully enclosed mast / sensor system (AEM / S) in 1995. The entire structure is 28m high and 10.7m in diameter. It is the largest carbon fiber aquatic structure on US Navy ships.
4.Carbon fiber propulsion shaft
In the trend of reducing the weight of hulls, the weight reduction of the power transmission components of the propulsion system is also mentioned on the agenda. Typically on high-speed ships where two or four high-speed diesel engines drive waterjets through reduction gearboxes, the distance between the diesel engine and the gearbox, or between the gearbox and the waterjet propulsion device is shortened.
Especially in the small space of the catamaran, four diesel engines are required to be staggered. The power emitted from the front diesel engine must be transmitted through the rear diesel engine. Therefore, this requires a transmission with the lightest weight and the fewest parts. The use of a carbon fiber composite material drive shaft can easily achieve the purpose of reducing the weight of transmission parts.
5.Other components
Many navies are considering applying carbon fiber composite materials to weapon covers and deck shields, as well as missile impact shields to protect them from high-speed projectiles and grenades; some experts are developing applications of carbon fiber composite materials Bulkheads, doors and decks.
At present, carbon fiber is widely used in naval vessels. However, most mature technologies are only applied to relatively small naval ships, such as frigates, patrol boats, MCMV, etc., or non-structural and non-critical components of some large ships. Norion Composites is also actively studying the application of carbon fiber in the military industry. It has developed carbon fiber military transportation boxes and communication radar cases for a military research institute, and has successfully passed acceptance. It is believed that with the development and progress of science and technology, the application of carbon fiber composite materials on naval vessels will become increasingly mature and the application range will become wider and wider.