In the marine industry, the application of high-performance fibers improves structural strength and effectively reduces weight. This article briefly introduces several types of composite fiber reinforced fibers for marine ships, including glass fiber, carbon fiber and aramid fiber, and combines their application examples A review was conducted.
In the past fifty years, most of the improvements in composite structures for marine vessels have been achieved through better performance resins. However, fibers have also played an important role in the development of advanced composite laminates for marine vessels. Specifically, the use of glass fibers with excellent properties can increase the weight and optimize the strength and rigidity of the material. However, it was later discovered that by using high-strength / high-modulus fiber materials such as carbon fiber, aramid fiber, etc. in combination with glass fiber, a more efficient and economic composite structure can be produced.
1. Application of glass fiber in marine ships
Due to its cost and relatively good strength-to-weight characteristics, glass fibers account for more than 90% of the reinforcing fibers for plastics; in addition, glass fibers have good chemical resistance and processability. However, when a load is applied for a long time, the excellent tensile strength of the glass fiber may decrease.
Due to its good strength properties and resistance to water degradation, E-glass (lime aluminum borosilicate) fibers are the most commonly used reinforcement materials for marine composites. The tensile strength of S-glass (silica, aluminum, and magnesium oxide) fibers is increased by about one-third, and it can exhibit better fatigue resistance. Because the cost of S-glass fiber is about three to four times that of E-glass fiber, its use in the marine industry is limited. Table 2 shows the performance comparison of some high-performance fibers.
2. Application of carbon fiber in marine ships
2.1 Overview of carbon fiber characteristics and its application in the marine industry
Carbon fiber includes high-strength medium-modulus carbon fiber and high-modulus carbon fiber (also known as graphite fiber). The carbon content in high-modulus carbon fiber is above 99%, while the carbon content in high-strength medium-modular carbon fiber is 93-95%. So far, all continuous carbon fibers have been made with organic precursors. In addition to PAN (polyacrylonitrile), they also include viscose and asphalt.
Carbon fiber has the highest strength and rigidity of all commonly used reinforcing fibers, and the fiber will not be subjected to stress fracture or stress corrosion like glass fiber and aramid fiber. In addition, the high temperature resistance of carbon fiber is particularly prominent. The main disadvantage of PAN-based carbon fiber is the relative high cost, which is the result of high raw yarn cost and high energy consumption manufacturing process.
The application of carbon fiber in the composite structure of marine ships is most suitable for the design limited by rigidity, such as a long and thin body and a structure with a small cross-sectional modulus. This is why carbon fiber is often used in catamarans and trimarans. Some ships with a large area, such as hovercraft or M-Ship concept ships, can also benefit from the carbon fiber sandwich structure.
In addition, carbon fiber is also specifically used for composite masts, rudder posts and other sailing hardware, and for truss covers when the truss height is limited.
At present, the fibers used in high-end sailboats are all carbon fibers. For example, in the fiercely competitive TP52 world sailing competition, almost 100% of the sailboats use carbon fiber.
2.2 Application examples of carbon fiber in marine vessels
M-Ship built the carbon fiber Stiletto, a double-M hull ship, 80 feet long and 40 feet beam. The ship's full load draught is 3 feet and the design speed is 50-60 kts. Its superior performance is based on M Ship Co.'s global patented technology, which can recapture the bow wave, thus creating an air cushion for more effective planning.
The M80 Stiletto is also striking because it is the largest naval ship in the United States and is constructed with carbon fiber composite materials and epoxy resins to produce a very light but strong hull.
2.3 Application of high modulus carbon fiber in marine ships
New Zealand High Modulus is a world-leading provider of composite technology and offshore structural engineering services. The company is currently developing high-modulus carbon fiber in all three projects.
The first is a 37m long 60-section vacuum-infused carbon fiber / epoxy / foam motor yacht. The designer is the British Rob Humphreys yacht design company, and the builders are McMullen and Wing in New Zealand. The project uses a lot of ultra-high modulus fibers, mainly used for very light internal cortical structures such as deck panels.
The second is a 40-meter-long luxury day sailor ship, which uses carbon fiber prepreg, foam and honeycomb core structure. The designer is Javier Soto Acebal in Argentina, and the builder is Wally in Italy. The project uses a considerable amount of high-strength medium-mold carbon fiber in the hull and deck to obtain overall rigidity, while the rudder stock contains standard modulus, high-strength medium-mold, and high-modulus carbon fiber.
The third is a large number of cooperation with Amsterdam Rhebergen Composites, mainly around the mast structure of large (80-120 meters) motor yachts. These structures mainly depend on their vibration behavior, so more and more high modulus carbon fibers (mainly Japan Toray M46J and Toho HS40) are used in the structure to increase rigidity but not increase the weight in order to adjust the inherent structure frequency.
3. Application of aramid fiber in marine ships
3.1 Characteristics of aramid fiber and its application in marine industry
The most common aramid fiber currently on the market is Kevlar® developed by DuPont, which is an organic reinforcing fiber. The use of aramid fiber can be traced back to the early 1970s as an alternative to tire steel belts. The outstanding characteristics of aramid fiber are light weight, high strength and modulus, impact resistance and fatigue resistance, and woven.
Aramid fibers are not as compressive as glass fibers because they exhibit non-linear plasticity at low strain values. The water absorption rate of unimpregnated Kevlar® 49 is greater than that of other reinforcement materials, although the ultra-high modulus Kevlar® 149 has a water absorption rate that is nearly two-thirds less than that of Kevlar® 49. If the proper weaving method and processing technology are adopted, the unique characteristics of aramid can be fully utilized.
3.2 Application example of aramid fiber in marine industry
For example, the Tawainese Patwanis patrol boat of the Seventh Peacekeeping Police Corps in Taiwan, this patrol boat built by Longteng Shipbuilding Company is 92 feet in length. The shipyard based in Taiwan, China has built six patrol boats to date, and all patrol boats use Kevlar / E-glass in the main structure.
By mixing Kevlar® fiber / glass fiber on these ships, the strength of the hull and other structures can be improved, and the speed loss weight can be reduced; and after mixing glass fiber and Kevlar, the problem of hygroscopicity is successfully solved. By using low-cost glass fiber mixed woven, the overall material cost is also reduced.
4. High-performance fibers for other marine marine composite materials
Other high-tech fibers such as basalt have yet to gain a foothold in the marine market. Although basalt fiber has high modulus characteristics, in practical applications, it is found that basalt unidirectional materials are not much stronger or harder than glass fiber unidirectional materials. However, due to its potential for ultra-high strength, ultra-high heat resistance and flame retardancy, basalt fiber also has great potential for development in the marine industry.
Nova Craft Canoe has developed a laminate that combines Kevlar® fiber and carbon fiber and is coated by the infusion process. The result is a hard canoe that is surprisingly lightweight and easy to handle.
Although high-performance carbon fiber and Kevlar® fiber have made significant progress in the field of marine composite materials, glass fiber is still the main force in the industry. Of course, when the weight is higher, it is often reasonable to use Kevlar® or carbon fiber laminates; for designs with limited rigidity, carbon fiber unidirectional materials can help optimize the laminate.