Abstract: This study investigates the uniaxial tensile behavior and numerical simulation of 1311RTM/GW300 unidirectional fiber composite laminates fabricated by variable-angle tow steering seam laying technology, aiming to explore the influence of fiber orientation deviation on mechanical properties and failure modes. The results indicate that, the stitched specimens exhibit reduced tensile strength and stiffnesscompared to non-stitched specimens. The fracture locations and crack propagation paths consistently correspond to the distribution of stitching needle traces, demonstrating that local fiber orientation deflection affects mechanical performance. A modeling approach reflecting fiber deflection characteristics at stitch points is developed, combined with Hashin’s damage criterion to simulate fiber deflection and damage evolution. The predicted tensile strength and modulus exhibit good agreement with experimental results, and the strain distribution characteristics match the test observations.

Key words: variable angle tow placement, composite materials, uniaxial tensile test, fiber deflection