What are the characteristics of carbon fiber electric scooters?
With the increasing awareness of environmental protection, the carbon fiber electric scooter has been launched strongly, so what is the difference? What are the characteristics?
Carbon fiber is an inorganic polymer fiber with a carbon content of more than 90%. Among them, the carbon content is higher than 99% called graphite fiber. The microstructure of carbon fiber is similar to artificial graphite, which is a chaotic layered graphite structure. The spacing between the layers of carbon fiber is about 3.39 to 3.42A. The arrangement of the carbon atoms between the parallel layers is not as regular as that of graphite, and the layers are connected by van der Waals forces.
The structure of carbon fiber is usually regarded as composed of two-dimensional ordered crystals and pores. The content, size and distribution of pores have a greater impact on the performance of carbon fiber.
When the porosity is lower than a certain critical value, the porosity has no significant effect on the interlaminar shear strength, flexural strength and tensile strength of the carbon fiber composite material. Some studies have pointed out that the critical porosity that causes a decrease in the mechanical properties of materials is 1%-4%. When the pore volume content is in the range of 0-4%, every 1% increase in the pore volume content will reduce the interlaminar shear strength by approximately 7%.
Through the study of carbon fiber epoxy resin and carbon fiber bismaleimide resin laminate, when the porosity exceeds 0.9%, the interlaminar shear strength begins to decrease. It is known from the experiment that the pores are mainly distributed at the interface between fiber bundles and between layers. And the higher the pore content, the larger the pore size, and significantly reduce the area of the interface between layers in the laminate.
When the material is stressed, it is easy to break along the interlayer, which is the reason why the interlayer shear strength is relatively sensitive to pores. In addition, the pores are stress-concentrated areas with weak bearing capacity. When stressed, the pores expand to form long cracks, which are destroyed.
Even if two types of carbon fiber laminates have the same porosity (using different prepreg methods and manufacturing methods in the same curing cycle), they also exhibit completely different mechanical behaviors. The specific numerical values of mechanical properties decrease with the increase of porosity are different, which is manifested in the large dispersion and poor repeatability of the influence of porosity on mechanical properties.
Due to the large number of variable factors, the influence of pores on the mechanical properties of composite laminates is a very complex issue. These factors include: the shape, size, and location of the pores; the mechanical properties of fibers, matrix and interfaces; static or dynamic loads.
Compared with porosity and pore length-to-width ratio, pore size and distribution have a greater influence on mechanical properties. And it is found that large pores (area>0.03mm2) have an adverse effect on the mechanical properties, which is attributed to the influence of the pores on the crack propagation in the glue-rich zone between the layers.