Prediction of effective mechanical properties of 2D triaxially braided composites using a geometrical model incorporating flat portions of composite yarns

This study aims to predict the effective mechanical properties (EMPs) of a 2-D triaxially braided composite (TBC) using an analytical model and to investigate the effects of various geometric parameters on them. The 2-D TBC, a type of braided textile composite, consists of an axial yarn and two braider yarns that are oriented in different diagonal directions within a plane, alternating between running below and above each other. A geometrical model is built considering the flat portion of the composite yarn to adjust the fiber volume fraction of the 2-D TBC while keeping other parameters constant. The prediction method is verified by comparing it with experi-mental and predicted results reported in various references, demonstrating good agreement. A parametric study indicates that geometric parameters affect the undulation path of a braider yarn and the volume content or each composite yarn, resulting in significant impacts on EMPs. The proposed prediction method is competitive in terms of computing time compared to finite element-based methods and can contribute to the design and improvement of composite structures.