Carbon Fiber Chopped Mechanism Investigation And Equipment Optimization

Based on Hertz contact theory and Griffith crack theory build up the Hertz cutting theoryand brittle wreckage theory to explain the carbon fiber how to cut off. Base on the Hertzcontact theory reduce the contact stress of two orthogonal cylinders. Based the Hertz contacttheory while the contact stress is over ultimate strength, carbon fiber is cut off by cutter.Based on the Griffith crack theory and the cutting parameters build up the carbon fiber brittlebreaking off model. The carbon fiber brittle breaking off model is a theory that the defects incarbon fiber sharply decrease the strength. Carbon fiber is bent by the cutter and the strain ofthe external layer of the carbon fiber is largest. While strain in carbon fiber is over the limitingstrain, the crack expands at the place that exist the defects and expands along the defects,finally the carbon fiber is broken off. Then validate these two models which one is right bycalculating the stress at contact area, taking SEM photos and simulating contact stress andstrain with Deform. The result shows that the the carbon fiber brittle breaking off model isbetter. At last based on the carbon fiber brittle breaking off model optimize and determine theparameter of the carbon fiber cutting device, including the cutter penetration depth, the heightof the rob, the material of the cutter, the material of the rubber covered roller and the radius ofthe cutter rollers and the rubber covered roller.