Stiffness Prediction of Triaxial Braided Composites Accounting for Manufacturing Parameters

Abstract

Textile composites are applied to aerospace and automotive industries because they have good fatigue characteristics, and higher specific stiffness and strength compared to metallic materials. In addition, textile composites have better out-of-plane performances such as the resistance of impact and inter-laminar delamination, in addition to greater structural flexibility than the traditional unidirectional composite materials. In this paper, we studied a stiffness prediction method for the effective stiffness of triaxial braided composites accounting for manufacturing parameters such as fiber volume fraction, number of filaments in a yarn, braiding angle, and gap between fiber yarns. The repeating unit cell (RUC) of the triaxial braided composites and the geometric model of yarn architecture were defined in consideration of the gap between adjacent yarns. The gap size between yarns was measured from the photographic image of the cross-section of the triaxial braided composite specimens. The fiber yarn discretization method and the stress averaging method were applied to predict the effective mechanical properties of triaxial braided composites. The predicted properties by the proposed model have good agreement with experimental results.