Investigation of the Z-binder role in progressive damage of 3D woven composites

The lack of strengthening mechanisms in the through-thickness direction of two-dimensional (2D) laminated composites often results in the incubation and initiation of distinct damage patterns such as delaminations and cracking. To address this issue, 3D woven composites containing z-binders have been introduced to provide means for enhanced damage tolerance. To assess the benefits of such novel composite architectures, this article uses an experimental mechanics approach coupled with a multiphysics nondestructive evaluation and characterization methodology involving Digital Image Correlation (DIC), Acoustic Emission (AE) and X-ray micro-computed tomography (micro-CT) to investigate the role of z-binder in the damage process of a specific example of a 3D composite. The novelty in this approach stems from the combined evaluation of globally calculated and locally resolved strain patterns which track the 3D damage process. Strain localizations are linked with out-of-plane deformation related to damage and are cross validated by the AE data and micro-CT analysis.