Investigation of fiber slippage in the chopping process of carbon fiber tows under rigid support

As an important application form of carbon fiber (CF), short CFs and their production process have self-evident research value. In this work, the chopping process of CF tows under rigid support and the essential cause of high cutting forces were explored. Large-tow CFs containing 1–3000 single filaments were chopped, and the fracture processes were observed and described. It was found that obvious fiber slippage phenomena and intermediate fracture behaviors occurred during the chopping process. These factors not only increased the cutting force but also caused an uneven distribution of the cutting force along the width. A mechanical model was established to explain the fiber slippage and intermediate fracture. Based on material mechanics and analytical mechanics, the real process of fiber slippage and intermediate fracture was described by Hamilton’s principle. Moreover, a width constraint experiment was designed to indirectly verify fiber slippage phenomena and intermediate fracture behaviors. Through the analysis of the stress curve, it was proven that a reasonable width constraint could effectively limit fiber slippage and improve the uniformity of the distribution of the cutting force along the width of the tool, thus reducing the cutting force. This work can be used as an excellent guide for the chopping process in CF production.