Carbon fiber products are inorganic polymer fiber materials with high carbon content, it is "soft outside and rigid inside", lighter than metal aluminum, and its strength is higher than steel. It comes in four product forms: fiber, cloth, prepreg billet and cut fiber. Fabric refers to fabric made of carbon fiber; Prepreg billet is the carbon fiber in one direction uniformly arranged, and the carbon fiber or fabric through resin impregnation to transform it into sheet; Staple fibers refer to short strands. In different ratios, these products and resins are used together to form carbon fiber reinforced composites (CFRP). At present, the new materials used to manufacture carbon fiber sports equipment accessories are mainly composite materials, and carbon fiber composite materials are the best of them. In a sense, modern competitive sports is a sport that challenges the limit of human physical strength, and the slight improvement of any world record often needs and relies on the promotion of science and technology. The use of new materials to improve the performance of competition equipment, so as to improve sports performance cases are not uncommon.
First, the advantages of carbon fiber composite materials for sports equipment
1, light quality like poles, golf clubs, tennis rackets, bicycles, skis, kayaks and other sports equipment that rely on manpower to make its movement, people want its quality as light as possible; Even the equipment that relies on other forces than manpower to make its movement, such as racing cars, sailing boats, motor boats, etc., is also light under the same conditions. Carbon fiber composites have incomparable advantages in this respect, and their density is 1.76 to 1.80. g/cm3, the composite density is 1.50 ~ 1.60  g/co, while steel is about 7.87  g/cm3, aluminum 2.7  g/cm3, titanium 4.5  g/cm3. Obviously, carbon fiber composites are much lighter than metal materials.
2, high specific strength and high specific modulus of carbon fiber composite material specific strength (strength per unit mass) and specific modulus (modulus per unit mass) are 4 times and 3 times of Chinese fir, 3.4 times and 4.4 times of Chinese Indus wood, 7 ~ 1  of steel; 2 times and 3-5 times. Outstanding specific strength, specific modulus, so that it can be used to manufacture light and strong and rigid products, especially suitable for the production of sports equipment.
3, the fatigue strength of large carbon fiber structure is stable, and its strength retention rate can still reach 60% after millions of cyclic stress fatigue tests, while steel is 40% and aluminum is 30%. High fatigue resistance makes the service life of sports equipment longer.
4, thermal expansion coefficient of small carbon fiber thermal expansion coefficient at room temperature is almost negative, when the temperature is 200 ~ 400℃, its thermal expansion coefficient is zero; When the temperature is below 1. At 000℃, the coefficient of linear expansion is 1.5×10 K.
5, the damage safety performance is good in carbon fiber composite materials, due to the role of the matrix, the strain of each fiber is basically the same when it is pulled along the direction of the fiber. Due to the stress transmitted by the matrix, most of the fibers still play a role except at the fracture. The breakage of individual fibers will not cause a chain reaction and catastrophic rapid damage, so the damage safety performance is very good.
6, the polymer matrix of carbon fiber composite material with good damping performance has viscoelasticity, and there is friction in the matrix and the interface where there are micro-cracks and de-bonding. In the vibration process, the viscoelasticity and friction convert part of the kinetic energy into heat energy. Therefore, the damping is larger than that of steel and aluminum alloy, and the damping can be increased if specific measures are adopted.
7, the development of large composite molding technology has greatly improved the design freedom. Anisotropy is a prominent feature of fiber composites. By changing the layup direction and way of fiber, the stress state in a certain direction can be locally enhanced or enhanced. It can be designed according to the age, gender, skill level, physical strength and other different situations of the players to maximize the use of sports equipment, which is difficult to achieve with isotropic metal materials. Second, the product form of carbon fiber and the main molding technology for sports equipment Carbon fiber composite materials can be formed as a whole through reasonable design, which can save many combined frames and assembly frames, and reduce production costs. With the development of technology, there are many molding methods for sports equipment, including winding molding, die molding, RTM molding, pultrusion molding and other technologies.
1, winding molding technology in a special winding machine, the prepreg blank evenly and regularly wound on a rotating mandrel, later curing, remove the mandrel to obtain products. The winding method is suitable for the manufacture of simple rotating bodies, such as cylinders, spheres and some positive curvature rotating or cylindrical products, and can also be used for the manufacture of non-rotating parts. Its remarkable feature is that the fiber can be arranged according to a certain law according to the stress of the product, so as to give full play to the strength of the fiber and obtain light and high strength products; In the process can achieve continuous, mechanized production, and short production cycle, high production efficiency, low labor intensity; The disadvantage is that the core mold needs to be removed after the product is cured, and it is not suitable for the manufacture of products with concave curved surface. Golf clubs and fishing rods can be made in this way. 2, die molding technology Die molding process is a method of molding composite products with the help of heating and pressure curing in a closed die cavity. The die is composed of two parts, the negative die and the positive die, and the reinforcing material is generally cut fiber felt, continuous fiber felt and fabric. The molding method has high production efficiency, accurate product size and smooth surface, especially suitable for manufacturing large quantities and products with high precision and repeatability requirements. Products with complex structure can be formed at one time, without auxiliary processing (such as turning, milling, planing, grinding, drilling, etc.), and the appearance and size of products have good repeatability. Its disadvantages are: mold design and manufacturing is complex, the initial investment is high, easy to be limited by equipment. 3, RTM molding technology RTM(resin transfer molding, referred to as RTM) is a more commonly used molding technology for composite materials. The technology is to lay the fiber or preformed blank into a closed mold cavity, inject the resin liquid into the mold cavity with pressure, soak the fiber or preformed blank, and then cure and release the molded product. The advantages of RTM technology are: it can manufacture complex composite materials with high quality, high precision, low porosity and high fiber content, and obtain smooth double surfaces without gelcoat resin; Short time from design to production, high production efficiency; RTM molds and products can be designed using CAD, mold manufacturing is easy, material selection is wide; RTM molded components and pipe fittings are easy to achieve local reinforcement or manufacture local thickening components, and composite materials with core materials can be formed at one time; Less volatilization in the RTM molding process is conducive to protecting workers and the production environment. RTM technology is currently used to mass-produce body parts for bicycles and rowboats.
4, pultrusion molding technology for the continuous production of fiber composite profiles. Pultrusion refers to a method in which fiber bundles or ribbon fabrics are drawn by external forces, impregnated, extruded, heated and cured, and cut at fixed length to make linear products with specific cross-sectional shapes and lengths. The impregnated continuous fiber passes through a molding mold with a certain cross-section shape, and is cured in the mold cavity or gel in the mold cavity, and is heated and cured in the mold. Under the action of traction machinery, the infinite length of the profile product can be continuously pulled out. Pultrusion molding process is simple, high efficiency; In the pultrusion process, the strength of the reinforced fibers can be utilized effectively because they are arranged in parallel axial direction. Isotropic products can be prepared by using fiber felt reinforced materials. The transverse strength of the product can be improved by using braided tape. Pultruded products have the characteristics of high strength, light weight, easy decoration and good surface quality. These properties are ideal for many types of sports facilities and related applications, such as fishing rods, bows, poles, ski poles, etc.
The higher the specific strength of carbon fiber composite materials, the smaller the weight of components; The higher the specific modulus, the greater the stiffness of the component. Therefore, making full use of the characteristics of carbon fiber composite materials can improve the performance of many sports.
1, carbon fiber pole vault in the first Olympic Games was officially absorbed as a competition event, when the pole was made of hickory wood, strong and heavy, lack of flexibility, poor energy storage characteristics of the players' kinetic energy is mostly wasted, so the better result of jumping out is only 3.3. m. Later, bamboo poles replaced wooden poles, in which the light weight of the air is conducive to running, and the elasticity is conducive to the transformation of energy. In the 1960s, athletes began to use nylon poles, and soon nylon poles were replaced by glass fiber poles. The continuous reform of pole materials has made the world record repeatedly brushed. Now the pole has developed to the fourth generation, glass fiber and nylon have been replaced by carbon fiber composite materials with better performance, and the material of different parts can be designed according to the difference in the force of the pole, so that the overall performance is better. The new carbon fiber pole can ensure that the pole is flexible and strong without breaking or kinking, and it can convert the kinetic energy of the athlete holding the pole to the elastic deformation energy of the pole. When the pole is bent to a large arc, this part of the elastic deformation energy is released and converted into the potential energy of the athlete, helping the athlete to jump in the air and fly over the bar.
2, carbon fiber golf accessories in the 1930s steel rod is the American standard golf club, in 1972 the United States first made of carbon fiber composite clubs, to 1998 the number of carbon fiber golf clubs significantly more than steel rods. Golf clubs are composed of grips, club bodies and club heads, and golf clubs made of carbon fiber composite materials can reduce the weight of about 10% to 40%. According to the law of conservation of momentum, when the total weight of the golf club is certain, the head weight of the golf club is lighter than that of the swing speed, which can make the ball obtain a larger initial speed. In addition, the carbon fiber composite material has high damping properties, which allows the ball to be hit longer and farther.
3, carbon fiber tennis racket The development trend of tennis racket is large, lightweight. At present, most of the high and mid-range tennis rackets in the world are made of carbon fiber composite materials. Large tennis rackets need to be made of lightweight, strong and larger than the mold carbon fiber composite material, which can withstand the tensile strength of the cable than the wooden racket frame, so as to ensure that the hit does not deform. The carbon fiber composite material with good vibration damping gives the athlete comfort and also makes the tennis ball obtain a larger initial speed.
4, carbon fiber bow and arrow in the archery project, improving the performance of archery equipment is an important way to improve the performance of archery, and the main way to improve the performance of its equipment is to improve the specific elasticity of the bow and arrow. The best bow in the world today is a series of carbon fiber composite materials, and the bow arm (bow piece) made of carbon fiber composite materials can withstand 50 % nbsp; The bending stress of kg/Hun2 gives the arrow its initial speed and long range. The fatigue resistance of carbon fiber composite material is unmatched by FRP and metal materials, so the service life of the bow arm is longer.
5, carbon fiber bicycle With the rapid development of modern society, the bicycle is not only a means of transportation and transportation, but also has a variety of functions such as fitness, tourism, competition and so on. The frame, front fork parts, wheels, crankshaft and seat bracket of high-end bicycles are made of carbon fiber composite materials, which not only makes the appearance of the bicycle more beautiful, but also gives the body good rigidity and shock absorption performance. The weight of the car body is further reduced, and the riding comfort is better.
The rapid development of modern science and technology has an unprecedented impact on sports. The sports competition in today's world is actually the competition of science and technology, and advanced and novel materials are one of the important conditions to improve the level of sports science and technology. Nowadays, in many sports, people's physical and mental stimulation have almost reached the limit, the victory and defeat are often only between the very small, it is difficult to win only by strong muscles and good competitive state, athletes are increasingly relying on the wisdom of scientists, and the fight is equipment. It is expected that through the upgrading of carbon fiber sports equipment accessories to drive athletes to challenge the limit, it can be said that the modern Olympic Games is no longer purely than which country's athletes run faster, jump higher, lift heavier, behind the competition between athletes and athletes, is the comprehensive competition of science and technology development and people's cohesion. The records in the Olympic Games are not only the embodiment of human breaking through physiological limits, but also the concentrated demonstration of scientific and technological innovation in sports.