Tensile failure of multiaxial 3D woven composites with an open-hole: An experimental and numerical study

In the present work, the multiaxial 3D (M3D) woven composites and 3D layer-to-layer (3D LTL) interlock woven composites were designed and manufactured. Both unnotched and notched specimens of two composites were tested in quasi-static tension, and the macro mechanical behavior characteristics of all specimens were monitored using the digital image correlation (DIC) technique. Based on the meso-structure characteristics of the M3D woven composites, a macro-meso coupling and full-scale analysis model for the centrally notched specimens was proposed. Furthermore, the progressive damage analysis was performed to simulate the damage evolution processes of the open-hole (OH) specimens, and the failure mechanisms were revealed in cooperation with the CT measurement. The study concluded that the reduction in tensile strength for the OH-M3D composites was about 19.8% compared to the unnotched strength, which was significantly lower than the 3D LTL case. Besides, the strain field in the loading direction uniformly distributed on the surface of the OH-M3D specimen, and the notched plate failed along the + 45° and −45° directions, exhibiting a diamond like fracture behavior. The interwoven structure of M3D specimen with the + 45° and −45° yarns influenced the stress distributions in the vicinity of the hole and damage mode.