Synergistic Regulation of Carbon Fiber Orientation and Mechanical Anisotropy by the FGF Shear Flow Field

ABSTRACT

During fused granulate fabrication (FGF) of fiber‐reinforced thermoplastic composites, fibers preferentially align along the flow direction, inducing pronounced mechanical anisotropy. This inherent directional dependence severely restricts their deployment in high‐performance, multiaxial load‐bearing structures and represents a critical bottleneck for FGF adoption in advanced manufacturing sectors. To address this challenge, a shear screw (SS) incorporating integrated shear‐inducing elements was developed. Structural optimization was performed using a coupled simulation‐experimental methodology, enabling precise spatiotemporal control over carbon fiber orientation. Comparative analyses against a conventional screw (CS) demonstrate that the SS promotes a helical carbon fiber orientation regime, significantly attenuating the mechanical property disparities between orthogonal printing directions. The tensile strength anisotropy index decreased from 0.46 to 0.16, indicating a significant reduction in mechanical anisotropy. Concurrently, the SS favorably modulates crystallization kinetics, yielding tensile strength enhancements of 22% and 91% along the 0° and 90° printing directions, respectively, with corresponding improvements of 80% and 98% in tensile modulus. The present work introduces a high‐efficiency screw configuration for producing high‐performance composites with reduced anisotropy through FGF technology. Featuring direct interchangeability with standard screws in commercial FGF systems, this design eliminates the need for hardware retrofitting, thus facilitating low‐cost, rapid technology implementation. This development carries significant implications for scaling up the industrial application of advanced composites in aerospace, automotive, and other high‐value manufacturing domains.