Meso-macro numerical modeling of noncircular braided composite parts based on braiding process parameters

In the past few decades, the applications of composite structures reinforced with braided preforms have been growing increasingly in various industries due to their intrinsic properties. Therefore, their mechanical properties are worth studying experimentally, analytically and numerically. In this respect, the goal of the current study is to perform a finite element modelling on biaxially and triaxially braided composites with constant arbitrary cross-section. Thus, the braid angles formed by clockwisely and counter-clockwisely moving of carriers on noncircular parts, have been initially demonstrated to be unequal, unlike in circular parts. As a result, considering a parallelogram shape for the representative unit cell (RUC), the geometrical relationships for a RUC of 2D biaxially and triaxially braided composite are derived and implemented in VUMAT subroutine. Then, after determination of 3D effective stiffness matrix for each RUC, the finite element modelling is performed to predict bending behavior of final braided composite part. In these simulations, the stiffness variation all over the part is considered and mechanical behavior of composite parts is predicted based on the initial parameters of the braiding process. The obtained results from both experimental and simulations showed an acceptable agreement.