Dual-Scale Synergistic Design: Oriented Material Stiffness and Deposition Path Planning for Enhanced Performance in Large-Format Additive Manufacturing of Short Carbon Fiber Components

Short carbon fiber-reinforced thermoplastic composites (SCFRTPCs) are widely employed in energy, aerospace and competitive sports due to their high specific strength/stiffness and design freedom. The Large Format Additive Manufacturing (LFAM) process, as an advanced technology for fabricating thermoplastic composite components, enables the rapid production of complex large-scale composite components and prototypes. Nevertheless, achieving satisfactory mechanical load-bearing performance remains a key challenge. To overcome this limitation, a methodology was developed for manufacturing short carbon fiber/Nylon 6 (SCF/PA6) composite components with programmable load-bearing performance via large-format additive manufacturing-compression molding (LFAM-CM). This process innovatively synergizes material stiffness enhancement with component deposition path planning, utilizing the high-orientation and low-porosity tape-shaped beads produced by LFAM to fabricate components. The experimental results demonstrate a peak load capacity of 549N, representing 33%, 231%, and 144% enhancements versus randomly oriented fiber, high-porosity, and non-path-planned components, respectively. Simultaneous meso- and macro-scale bearing performance analysis demonstrated the cross-scale synergistic enhancement effect of this process on component load-bearing capacity. Finally, a systematic analysis of energy dissipation, stiffness, and damage tolerance revealed the underlying mechanisms for enhanced load-bearing performance. This work establishes an expanded design paradigm where multivariate coupling replaces linear structure-property relationships, providing practical frameworks for the development of next-generation functionally graded components with tailored mechanical-electrical-thermal multifunctionality.