Prediction and optimization design for thermal expansion coefficients of three‐dimensional n‐directional‐braided composites

Abstract

A new model based on thermomechanics analysis is established to predict the coefficients of thermal expansion (CTEs) of 3D n-directional (n = 4, 5, full-5, 6, or 7)braided composites in this article. In this model, relationships between stresses and strains generated in fiber and polymer matrix are portrayed by a bridging matrix to obtain elastic constants of yarns. Based on equivalent fiber cross-sections and space projections of yarns, effective overall CTEs of 3D n-directional-braided composites are obtained. We introduce parameterization into the finite element modeling to complete our verification. The theoretical predictions are consistent with the finite element method and existing experiments. This article gives detailed insights into the effect of braiding parameters on CTEs to explore indication of addition yarns for thermal expansion performance. As an application of the proposed model, we utilize an improved genetic algorithm with objective weight mechanism and dynamic mutation to obtain the multi-objective optimization design for zero expansion 3D-braided composites. POLYM. COMPOS., 40:2495-2509, 2019. © 2018 Society of Plastics Engineers under the consideration of fiber undulation and porosity, Kong et al. [25] established a finite element model of 2.5D C/SiC composites. On the basis of morphology of the yarn unit model and numerical analysis, Hu et al. [26] studied variations on the CTE of 3D-braided C/C composites. Moreover, Lu et al. [27] developed a model to investigate the effect of interfacial properties on the thermophysical properties of 3D-braided composites. As previously

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

“…[1] Methods for predicting the mesostructure of the braided preforms are the focus of considerable research on braided composite materials, [2][3][4][5][6] because the parameters of the mesostructure of the preform, such as the braiding angle, braiding pattern, the distance between the yarns, and cross section of the yarns determine the mechanical properties of the braided composites. The mesostructure of braided preforms in a majority of publications [7][8][9][10] relies on highly idealized geometric assumptions, for example, constant cross section, parallel yarn paths, or polygonal cross section, for the ease of modeling of the structures. In the manufacturing process of braided preforms, yarn deformation such as bending, shifting, and nesting are introduced, which are on top of the idealized mesostructure of the braids.…”

Thermo-mechanical behavior of 3D multi-directional braided composites based on a two-scale method

“…[36][37][38] For numerical prediction, Lu and Xia [39][40][41] used finite element methods (FEM) based on periodic boundary conditions to predict the CTE of 3D four-directional (3D4D), 3D five-directional (3D5D) and 3D full five-directional (3DF5D) braided composites. Guo et al 42 used an improved genetic algorithm to optimize the zeroexpansion design of 3D n-directional braided composites. Pottigar et al 43 presented 3D braided composites with zero, negative and isotropic CTE based on an analytical homogenization technique.…”

High‐temperature properties and failure mechanism of 3D six‐directional braided composites under out‐of‐plane compression

“…Three‐dimensional (3D) braided composite breaks through concept of traditional composite laminated structure and overcomes weak performance and poor impact resistance of laminated material. Three‐dimensional braided composite has been widely applied in aerospace, biomedical, automobile and other fields …”