Tailoring fiber arrangement in subsurface damage layer of unidirectional CFRP composites by reverse multi-pass cutting

While the directionality and integrity of microscopic fiber arrangement play an important role in governing the mechanical properties and deformation behavior of unidirectional carbon fiber reinforced polymer (UD-CFRP) composites, minimizing or eliminating the deformation-induced evolution of fiber arrangement is crucial for maintaining the high performance of the advanced composite materials. In the present work, we elucidate the depth-sensing deformation mechanisms of UD-CFRP under different cutting strategies of conventional single-pass and multi-pass by experiments and corresponding micromechanical finite element simulations. Experimental and simulation results reveal diversiform maps of fiber arrangement evolution in subsurface damage layer under different cutting strategies, as well as their correlations with machined surface quality in terms of surface finish, residual stress and mechanical properties. Subsequently, a novel cutting strategy of reverse multi-pass is proposed to tailor the directionality and integrity of microscopic fiber arrangement in subsurface damage layer, which is accompanied with reduced subsurface damage layer, lowered surface roughness and enhanced hardness and elastic modulus, as compared to the cutting strategy of conventional multi-pass. Current findings provide a theoretical basis for the understanding of formation mechanisms of machined surface of CFRP composites, as well as the rational selection of cutting strategies for improving the machinability of CFRP composites.