Study On Axially Compressive Behaviors Of Carbon Fiberwinding Composite Cylinders

Carbon fibers have excellent mechanical properties, such as high strength,high modulus, light. It has been widely applied in various fields. Windingmolding is an important forming method of carbon fiber composite materials. It isvery suitable for hollow products, which usually requires the materials towithstand high pressure and other special conditions. By studying the axiallycompressive behaviors of carbon fiber epoxy wounding composite cylinders anddoing finite-element analysis, we can have a full-scale understanding of theendurance and weak links of materials under the outside world. The important, italso can guide and improve production practice.This experiment focuses on studying the influences of cylinder size, windingangle, pre-crack angle and carbon nanotubes on the compression behavior ofwinding cylinder. Experimental results show that the compression performance ofcylinder with an aspect ratio of2:1is better than that is1:1, strengthening layercan significantly improve the strength of the end of the cylinder and increase theoverall compression performance of the cylinder. The experiment studiescylinders with different winding angles (20°,40°,60°and80°). According to theresults, except the40°winding angle, with the increase of the winding angle, thecompressive strength of the cylinder decreases and the strain increases. Thecompression strength and strain of40°winding angle are less than20°,60°and80°. Besides, with the increase of the winding angle, compression modulusdecreases while the compression efficiency increases. At the macro level,40°winding angles cylinders damage in the way of partial expand, while the othersmajor damage along the fiber winding direction. Furthermore, different windingangles correspond to different failure mechanisms,20°for the brittle failure,40° for the local buckling,60°and80°for the lamina bending. By observing thedisintegrating slag of the failure cylinders through optical microscope andresearching the failure mechanisms, we also get the conclusion that compressionefficiency increases with the winding angle increasing.According to the analysis of the destructive path of the cylinders undercompression experiment, we suppose that the closer of the pre-crack angle andwinding angle, the lower of the compressive strength and modulus of the cylinder.The experimental results confirm this conjecture. Besides, during the experimentwe also observe the failure of the cylinder always begin from the pre-crack, andthe results of finite-element simulation agree to this appearance.Carbon nanotubes do not have a significantly enhanced effect ofcompressive strength on the cylinder, but the modulus and stiffness of thecylinder increase, the failure strain decreases.