Mechanical properties of carbon fiber composites with various wear characteristics during knitting process

The inherent brittleness of carbon fiber (CF) presents a significant challenge during the knitting process, as the yarn is prone to breakage under bending stress, resulting in the occurrence of hairiness that directly impacts the mechanical properties of the composites. Therefore, it is imperative to examine the frictional and wear characteristics of CF bundles in order to minimize potential damage incurred during the weaving process and enhance the overall properties of composites. This study initially modified the CF through flexible coating with polydimethylsiloxane (PDMS), followed by preparing a knitted preform. Subsequently, an investigation was conducted to assess the impact of contact area and sinking depth on CF damage. Furthermore, the finite element method was employed to simulate stress distribution during the loop formation of CF. Finally, the impact of CF wear on the mechanical characteristics of the composite was examined. After heat treatment and low damage treatment, the tensile strength and bending strength of CF@PDMS/TD-C increased by 16.7 % and 23.64 %, respectively. The energy absorption performance was measured at 17.79 J, 27.84 J, 37.77 J, and 42.34 J for impact energies of 20 J, 30 J, 40 J, and 50 J, respectively. These findings establish an experimental and theoretical foundation for mitigating damage during the weaving process.