Characterization Of Ultra-Thick Three-Dimensional Orthogonal Woven Composite

As a typical 3D construction composite, 3D orthogonal woven composites are known to have superior mechanical properties, especially the high resistance to delaminate and fatigue.The objective of this work was to study the mechanical properties of ultra-thick 3D orthogonal woven composites in comparison with that of 2D laminates. An automatically 3D weaving machine was used to produce the 15 mm thick 3D woven performs. This technique required to insert multiple filling (or weft) yarns simultaneously. Vacuum resin transfer molding was used to consolidate the final composites.Composite samples of the two kinds of structures have been tested for tensile strength and modulus, compression strength and modulus, interlaminar shear strength, and 3-point-bending strength and fatigue resistance. The results shown that all the quasi-static mechanical properties of 3D woven composites are all better than that of the 2D laminates due to low waviness of the warp and weft yarns and reasonably high fiber volume fraction (V_f) in the two directions since the Z yarn had low volume fraction of only 2.7%. The presence of Z yarn in 3D woven composites helped to promote interlaminar shear strength.The results of the 3-point-bending fatigue test showed that the fatigue property of weft direction was better than that of the warp direction. It indicated that the fiber volume fraction influenced not only static properties but also the dynamic properties. Theoretical analysis was used to predict the fatigue residual modulus of the composites. The results showed that the experimental data correlate reasonably well with the theoretical predictions.