The Mechanical Property Test Of High-performance Single-filament Carbon Fiber

Carbon fiber and composite materials excellent performance, not only is the aerospace and military industries indispensable new material, but also in civilian industrial upgrading of new composite materials. Accurate measurement of the mechanical properties of carbon fiber composite materials and design is to understand the basis for the study of the relationship between microstructure and properties of carbon fibers are also important.Strength carbon fiber filaments can exclude the influence of composite molding process and intuitive performance carbon fiber performance is good or bad, its discrete monofilament strength is good or bad impact on the stability of the mechanical properties of the composites. In this paper, the Weibull distribution in the form of carbon fiber tensile properties were statistically summarized, analyzed and discussed one by one.Using Weibull distribution and Gauss distribution of three kinds of mechanical properties of carbon fibers are tensile properties; tensile strength, tensile modulus, fracture strain fitting obtained Weibull distribution fitting is more suitable for the three mechanical properties. The tensile strength of carbon fiber having a significant volume effect, fiber gauge or different diameters, the fiber tensile strength have a certain impact,three different samples gauge (10mm,18mm,25mm) analysis, with increasing gauge, the shape parameter is reduced, the average strength of the fiber is reduced, the scale parameter is reduced; With decreasing fiber diameter, the tensile strength increased, at the same time reducing the shape parameter,increased dispersion. By T300, T700, M40J three kinds of PAN-based carbon fiber tensile strength of Weibull distribution fitting to give maximum shape parameter T300, T700 minimum shape parameter, the higher the PAN-based fiber strength, the less its shape parameters, discrete greater. The coefficient of variation obtained shape parameters and fiber strength is directly proportional to both reflect the degree of dispersion fiber. Five laboratory-made pitch-based carbon fiber tensile strength distribution fitting Weber, reached a similar PAN-based carbon fiber pattern.A non-contact laser micrometer was introduced to a conventional single filament tensile testing instrument to directly measure small displacement of single carbon fiber samples, allowing the modified system to measure and monitor the change of Young's modulusduring the fiber stretching process simultaneously and accurately.The nonlinear behaviors of single carbon fibers from both polyacrylonitrile and mesophase pitch feedstock were studied and compared in terms of the coefficient describing the modulus dependency onstrain(y). It was found out all fivetypes of carbonfiber exhibitsimilar non-Hookean elastic behaviors, thattheiry increase with theinitialmodulus.The mesophase pitch based carbon fiber, with similarinitial modulusto that ofpolyacrylonitrilebased carbon fiber,hadmuch highervalue of y,presenting stronger non-linearity in mechanical properties.The increment of ywiththe initial modulus for mesophase pitchcarbon fibers wasmuch higher than that of polyacrylonitrile based carbon fibers as well.