Mechanical analytical modelling of non-axisymmetric overbraiding

Abstract

Overbraiding allows the production of complex hollow composite preforms. Various mechanical modelling methods have been proposed in the literature to help optimizing this process. However, these are either analytical, and computationally fast, but limited to axisymmetric braiding, or based on finite element methods (FEM) but computationally very expensive. The present work proposes a novel approach to model mechanically and in a computationally efficient manner the braid along its formation and deposition. Thereby, the geometrical and mechanical equilibrium of the whole braid in the convergence zone is described without symmetry assumption using a system of equations which is solved using the Newton-Raphson method. The new model, treating yarn-yarn friction, is evaluated using results from the literature, and demonstrates that friction is not the only physical mechanism that must be considered to simulate accurately the process. Finally, significant calculation time reduction is obtained compared to the most recent FEM simulations.

Metamodel-Based Uncertainty Quantification for the Mechanical Behavior of Braided Composites

“…Alternative analytical approaches based on differential geometry can be found in (Guyader, Gabor, and Hamelin, 2013) and (Na et al, 2014). More recent endeavors include a method correlating process and structure parameters via an oblique coordinate system and curve fitting (Mei et al, 2020) and a method based on the mechanical equilibrium of yarns (Imbert, Finckh, and Gresser, 2021).…”

High‐fidelity modeling of the braiding process for generating the realistic mesostructure of preforms in braided composites

“…The mesostructure of the preforms is determined by the yarn path and interlacement in the convergence zone. [12,13] To provide an accurate geometric model for structural design and performance analysis of braided composites, the convergence zone that links the process parameters and the geometric parameters of the preform mesostructure should be taken into account.…”

“…[18][19][20][21][22] However, the negligence of yarn-yarn interaction in the convergence zone was found to cause deviations in the prediction of yarn paths of the braided preform, as reported in the literature. [12,13] In order to improve the accuracy, analytical methods which can account for the normal and tangential behavior of the contact between the yarns have been established. These methods solve the yarn segments' tensile force and friction force to derive the yarn path.…”

“…[ 18–22 ] However, the negligence of yarn‐yarn interaction in the convergence zone was found to cause deviations in the prediction of yarn paths of the braided preform, as reported in the literature. [ 12,13 ]…”

“…Zhang's model provides a practical method to evaluate the friction in the biaxial braiding processes. Imbert et al [ 12 ] simulated the unsteady braiding process and studied the relation between the convergence zone and the braiding angle. However, the cross section of the yarns in Imbert's model is defined as a circle.…”