Nonlinear Degradation of Tensile Properties in Unidirectional <scp>CFRP</scp> Under Small Fiber‐Load Misalignment: Experiments and Macro‐Meso Analysis

ABSTRACT To address small‐angle misalignment between the fiber direction and loading direction that may occur during machining, assembly, and service of unidirectional carbon fiber reinforced polymer (CFRP) composites, this study combines tensile testing, macroscopic finite element simulation, mesoscopic representative unit‐cell (RUC) modeling, and fractographic analysis to investigate the effects of 0°‐3° misalignment on tensile response, strength degradation, and damage‐evolution trends in unidirectional CFRP. The results show that, for the present T300/2019B unidirectional CFRP system, [0] 8 lay‐up, specimen geometry, and cutting/testing configuration, the ultimate tensile strength decreases from 2305.23 to 1182.27 MPa as the misalignment angle increases from 0° to 3°, corresponding to an accumulated reduction of approximately 48.7% and indicating pronounced nonlinear strength degradation. Fractographic observations provide qualitative support for changes in failure characteristics; with increasing misalignment angle, fracture‐path irregularity, matrix cracking, fiber splitting, and stepped fracture features become more evident. Macroscopic simulations indicate that angular misalignment promotes a transition of the stress field from a relatively uniform distribution to edge concentration. Mesoscopic RUC analysis further shows enhanced local stress concentration near fiber surfaces and in the vicinity of the fiber/matrix interface. This study provides a macro‐meso mechanistic interpretation for tensile‐property degradation in unidirectional CFRP under small fiber/load misalignment.