On mechanical properties of double-sided-loop 2D woven laminated composites

Carbon fiber laminated composites are widely used in the aerospace industry due to their excellent lightweight and excellent mechanical properties. However, when subjected to external impact, delamination damage occurs between the layers of composite materials, and thus how to suppress delamination and improve the interlaminar strength of composite laminates has become the focus of the research field. Based on the idea of interlayer toughening, a new double-sided-loop two-dimensional (2D) woven laminated composites (DWLC) is designed, woven and laminated using the RTM molding process. DWLC is based on a 2D fabric with the introduction of loop warp yarns in thickness direction, which form Z-directional loops and thus form a synergistic toughening layer with the resin matrix between the layers after lamination during the forming process. In order to study the mechanical properties of DWLC, the tensile, compressive, interlaminar shear mechanical properties and damage behavior of DWLC are experimentally and numerically investigated. In addition, the internal damage and failure fracture are examined using micro computed tomography (Micro-CT). Strength prediction model of DWLC is established based on a representative volume element (RVE) with a mesoscopic geometric model. Three-dimensional (3D) Hashin and Von-Mises criteria are introduced as the failure criteria for the component materials. The results show that due to the existence of loops, the in-plane fiber volume content of DWLC decreases, resulting in a decrease of tensile and compressive strengths but an increase of interlaminar shear strength.