FRP is a common high-performance composite material. Carbon fiber resin composite materials exceed FRP in many aspects. The strength and elastic modulus depend on the performance of the raw fiber. Compared with glass fiber, the elastic modulus of carbon fiber is 4-6 times that of glass fiber, and the tensile strength is slightly higher than that of FRP. For example, the strength and elastic modulus of carbon fiber-epoxy resin composite materials exceed those of aluminum alloy and are even close to high-strength steel, which makes up for the disadvantage of low elastic modulus of FRP.
Carbon fiber has the highest elastic modulus, and composite parts can be allowed to work under the ultimate stress state, overcoming the disadvantage that glass fiber resin composite materials are only allowed to work under conditions below 60% of the ultimate stress. The mechanical properties of carbon fiber resin composite materials also improve with the increase in fiber content. The best content of 60%-70% (volume) of fiber in the composite material is optimal. When the fiber content is higher, the integrity of the composite material will be destroyed and the performance will decrease.
1. Carbon fiber composite materials have excellent fatigue resistance.
This is because the interface between carbon fiber and matrix in the composite material can hinder the propagation of cracks, and the imperfect combination of fiber and matrix is conducive to the blunting of the front part of the propagation crack. The cracks stop expanding in the direction of the load. The soft base of the composite material also has a hysteresis and hindering effect, so that the brittle cracks will not continue to expand. Carbon fiber composite components, if subjected to a force of about four times per square centimeter, can withstand cycles of up to 20 million to 30 million times (2,000 cycles per minute) without fatigue failure.
2. Carbon fiber composites have good impact resistance.
Someone shot a piece of carbon fiber composite material less than one centimeter thick with a gun at a distance, but could not penetrate it. What is interesting is that when other fibers (such as glass fibers and organic fibers) are mixed with carbon fibers as composite material reinforcements, the impact performance of this mixed fiber composite material can be 2-3 times greater than that of carbon fiber composite materials.
3. The strength loss of carbon fiber composite materials in high-temperature aging tests is smaller than that of fiberglass.
The anisotropy of the mechanical properties of broken fiber composite materials exceeds that of boron fiber composites and fiberglass. When the composite material is filled with fibers in the form of multi-dimensional partial weaves in space, this phenomenon is smaller than when it is filled with reinforcing fibers. In another case, cross-laying fibers can also reduce this phenomenon.
