Abstract: Combine with the fracture morphology, Acoustic Emission (AE) technology and Digital Image Correlation (DIC) method were used to study the law of deformation and damage of three-dimensional (3D) five-directional braided composites under transverse tensile condition. Transverse tensile mechanical response, AE characteristic parameters and deformation field information were analyzed. The results show that the limit load for 3D five-directional braided composites under transverse tensile condition is relatively low and the mechanical curve is divided into two phases including linear and nonlinear phases. The failure curve is nonlinear and related to the failure mechanism of transverse tension. The increasing trend of the cumulative counts can reflect the damage evolution process of transverse tension better. The transverse tensile fracture of 3D braided composites is not flush along the direction of fiber braiding and the failure modes are mainly matrix cracking, fiber deboning and few fiber fracture. The surface full-field information in the process of transverse tension reflects the damage evolution characteristics of the materials and provides basis for the structural health monitoring of 3D braided composites.

Key words: three-dimensional five-directional braided composites, acoustic emission, digital image correlation, transverse tension