Effect of weaving structures on the geometry variations and mechanical properties of 3D LTL woven composites

This paper presents a comprehensive experimental study of the effect of weaving structures on the geometry variations and mechanical properties of three dimensional (3D) layer-to-layer interlock (LTL) woven composites. 3D woven composites with four different weaving structures are prepared. Geometry variations of the unit cell structures are investigated based on the micro-computed tomography (micro-CT) images. Tension and compression tests are performed to the four composites. The digital image correlation (DIC) method is used to obtain surface strain fields of the specimens under tension load. Both tension and compression properties of the composites are affected by the waviness of load-bearing yarns. The addition of stuffer yarns significantly improves the warp direction performance. Nonlinear behavior, failure modes and scatter of testing results for the specimens are closely related to the weaving structures.