Effect of Braiding Angle on Low‐Velocity Impact Performance of UHMWPE 3D Braided Spacer Composites

ABSTRACT To meet the urgent demand for ultra‐lightweight and high‐energy‐absorption materials, this study employed ultra‐high molecular weight polyethylene (UHMWPE) fibers combined with a three‐dimensional (3D) braided spacer structure to systematically investigate the effect of braiding angle on the low‐velocity impact performance and damage mechanisms of the composites. Composites with three braiding angles (25°, 35°, and 45°) were fabricated and subjected to low‐velocity impact tests at energy levels of 10, 15, and 20 J. The structural regulatory role of the braiding angle was revealed through analysis of load–displacement curves, energy‐time responses, and macro and microscale damage morphology. The results showed that the braiding angle significantly influenced the dynamic mechanical response and failure behavior of the composites. Specimens with a smaller braiding angle (25°) exhibited higher initial bending stiffness (0.48 kN/mm at 10 J) and peak load (2.68 kN at 10 J) due to fiber alignment closer to the axial direction, resulting in faster impact response and more localized damage. Their failure mode was dominated by fiber‐driven compressive deformation, which maintained optimal structural integrity and yielded the highest residual compressive strength (209.1 MPa after 10 J impact). This study clarifies the mechanism by which the braiding angle regulates the impact performance of composites by controlling the fiber‐matrix load transfer path, providing a basis for the structural optimization and performance design of ultra‐lightweight protective materials.