Experimental research of the longitudinal compressive strength of carbon fiber

In order to confirm the compressive stress of carbon fiber, a method for the direct measurement of the compressive strength of carbon fibers was studied, and a direct measurement system of a single carbon fiber's compressive strength was set up. By using this system, high strength and modulus levels of PAN-based carbon fibers were examined at sample gauge lengths of 20 to 150 μm, and the compressive strength was shown to be constant when the length of carbon fiber is 20~90 μm. Additionally, with a gauge length from 90~150 μm, the mode of distortion was not compressed but flexed. Finally, the compressive and tensile strengths of some kinds of PAN-based carbon fibers were compared, showing that the compressive strength of carbon fiber increases with the rise of tensile strength, and the compressive strength is about 50% of the tensile strength, which provide some value to the design of composite materials.