Research on Testing Methods and Influencing Factors for Interlayer Fracture Toughness of Carbon Fiber Reinforced Composite Laminates

Abstract

Interlayer fracture toughness is a critical performance indicator for carbon fiber reinforced composite laminates, directly governing structural integrity under delamination-prone loading conditions. This study systematically investigates testing methodologies and key influencing factors affecting interlaminar fracture resistance. A comparative experimental framework was established across multiple standardized and modified test configurations-including mode I, mode II, and mixed-mode interlaminar fracture tests-using identical material batches to isolate methodological variability. Specimen geometry, stacking sequence, surface preparation protocols, adhesive interface quality, and environmental conditioning were each varied in controlled parametric studies. Quantitative fracture energy metrics were extracted from load-displacement records and crack propagation tracking. Statistical analysis revealed that interfacial roughness and moisture content exerted the strongest influence on measured toughness values, while test configuration choice introduced up to 37 percent variation in reported GIC values. The findings provide an evidence-based hierarchy of factor sensitivity and clarify discrepancies commonly observed across literature datasets, supporting more reliable benchmarking and design-oriented material qualification.