Carbon fiber tube is the most basic kind of carbon fiber products.
At present, it is mostly made by rolling or molding process. During the production process, different tubes are made by adjusting the mold. Carbon fiber tubes are widely used in drones, robotic arms, shafts, sports equipment and other components. For the application of carbon fiber in various fields, its performance can be analyzed through some data.
1. Density
The density of carbon fiber tubes is determined comprehensively by the ratio of carbon fiber strands to epoxy resin. It can be obtained by calculation that when the density of the carbon fiber tube is 1.5g/cm^3, the resin content accounts for 55.2%. Compared with the resin content of the prepreg, it is higher, indicating that the pores of the carbon fiber tube are too large, which seriously affects its mechanical properties.
When the resin content is about 38%, the density is 1.03g/cm^3, which is not much different from the resin content in the prepreg. Resin content has a great influence on the mechanical properties of composite products. The fluctuation of resin content will cause uneven distribution of mechanical properties, so the deviation of resin content should be as low as possible. It should be controlled within ±3% at least to ensure the stability of the volume content and mechanical properties of the carbon fiber tube.
2. Bending shear strength and modulus
When the carbon fiber tube itself is subjected to the lateral bending force, the tube wall also bears the shear stress in the vertical direction. After testing by the researchers, it was found that the theoretical bending shear modulus can reach 8.54GPa, but the measured value is 8.38GPa. , there is not much difference.
When the carbon fiber tube is bent and sheared, the shear stress is very complex, not only the tangential shear stress along the tube wall, but also the interlaminar shear stress perpendicular to the tube wall. Theoretically, the shear strength of this carbon fiber tube is 112MPa, and the actual measured value is 103MPa, which is also very close to the theoretical value.
3. Tensile modulus
Tensile modulus measures the maximum tensile force a fiber can withstand. Its unit is PSI, which indicates how many pounds of tensile force it can withstand per square inch. Carbon fibers with a tensile modulus below 34.8 million PSI will be classified as low modulus carbon fibers. Others include standard modulus, intermediate modulus, high modulus and ultra-high modulus. The tensile elastic modulus of ultra-high modulus carbon fiber is 72.5 million-145 million PSI (500-100 million kPa). In comparison, the tensile modulus of steel is about 29 million PSI (200 million kPa).
Using the real measurement data, you can know a number of performance indexes of the carbon fiber tube, and you can also judge whether the carbon fiber tube meets the actual needs of customers.