Mechanism‐Driven Regulation of Deposition Quality in Additively Manufactured Continuous Fiber Reinforced Polymer Composites: Balancing Rheology and Geometry

ABSTRACT This study investigates the multi‐factor coupling effects on the deposition quality of 3D‐printed continuous carbon fiber reinforced thermosetting epoxy composites. Utilizing Response Surface Methodology (RSM) combined with a Box–Behnken Design (BBD), the synergistic impacts of printing temperature, speed, spacing, and layer height on flexural properties were systematically evaluated. The established high‐precision quadratic regression models ( R ² > 0.98) revealed that internal porosity and fiber damage are predominantly governed by strong “saddle‐shaped” coupling effects: the geometric matching between printing spacing and layer height, and the rheological compensation between temperature and speed. By correlating 3D response surfaces with scanning electron microscopy (SEM) and micro‐computed tomography (CT) analyses, the physical mechanisms of defect formation under parameter mismatches were systematically elucidated. Multi‐objective optimization determined a global optimal process window (printing temperature (T) = 120°C, printing speed (V) = 500 mm/min, printing spacing (S) = 1.3 mm, and layer height (H) = 0.4 mm). Validation experiments demonstrated excellent predictive accuracy for flexural strength (604.97 MPa) with a relative error of only 2.1%. Notably, this optimal configuration minimized the internal void content to an ultra‐low level of 2.3% and effectively suppressed premature delamination, resulting in an actual flexural strength increase of 27.7% compared to the unoptimized baseline. Meanwhile, the observed deviation in flexural modulus was theoretically linked to deposition‐induced micro‐level fiber waviness.