Impact and Flexural Energy Absorption Mechanism of Hybrid Composites Interleaved CF/PA6 Fiber Papers Based On Real-Time Cracks Tracking

The effective utilization for recycled carbon fibers (rCFs) is significant for less pollution, low energy consumption and resource conservation. This paper proposed a path for reprocessing the recycled carbon fibers into CF/PA6 fiber papers using flexible papermaking technology. Then, the CF/PA6 fiber paper could be used as an interlayer component to continuous CF woven/epoxy resin composites to form hybrid composites. The configurations of hybrid composites and directions of papers effects on notched impact resistance and flexural performance were systematically discussed. The micro energy absorption mechanism was revealed based on real-time crack tracking. The results indicate that cracks migration between woven and paper contributes to impact and flexural energy absorption, most improving 22.64% and 40.85% respectively in one-layer paper with longitudinal direction in the middle location (L1). Whereas, there is a negative effect of hybrid composites on flexural strength and modulus compared with pure CF woven composites. The behaviors of hybrid composites with longitudinal direction of paper are greater than that with transverse direction on stress, modulus, and the absorbed energy in the same configurations. Furthermore, spatial flexural morphologies are also affected by damage path. The final failure modes integrate the continuous woven fabric composite and discontinuous CF/PA6 fiber paper composite, mainly including fiber and matrix fracture, fiber pull-out and delamination. It provides a guidance for material design and structural optimization in reusing of carbon fibers.