Trans‐scale thermo‐viscoelastic behavior prediction of 3D tubular braided composites

Abstract The prediction of viscoelastic behavior of resin‐based three‐dimensional (3D) tubular braided composites is important due to their long‐term application at different temperatures in fields such as aerospace. Based on the time–temperature superposition principle and the automatic translation algorithm, this study establishes isotropic and transversely isotropic thermo‐viscoelastic constitutive models for defect‐containing resin and yarn respectively. In addition, based on micro‐CT technology and multi‐scale continuum mechanics, a realistic trans‐scale finite element model from microscopic (fiber/matrix representative volume element [RVE], resin/pore RVE) to macroscopic (3D tubular braided composites) has been developed to sequentially simulate the long‐term viscoelastic properties of 3D tubular braided composites at different scales. The results show that defects have a minor effect on the viscoelastic properties of the matrix, while temperature significantly affects the time it takes for the elastic properties of the material to stabilize at all scales. Although the braiding angle does not affect the time for the axial compression relaxation modulus of 3D tubular braided composites to reach stability, it is positively correlated with the rate of change of the axial compression relaxation modulus. The accuracy of the proposed model is verified by good agreement with the experimental curves at different temperatures. Highlights A trans‐scale thermo‐viscoelastic constitutive model is established. The viscoelastic behavior of 3D tubular braided composites at different temperatures is predicted. Experimental curves show good agreement with the model predictions.