A coupled multi-scale method for predicting the viscoelastic behavior of resin-based 3D braided composites

A new alternative multi-scale calculation procedure was presented to characterize the time-dependent viscoelastic behaviors of resin-based three dimensional (3D) braided composites. The present investigation was processed based on micro-scale fiber/resin, meso-scale yarn/resin and macro-scale homogeneous composite. Integrating with the asymptotic expansion homogenization (AEH) method, the multi-scale physical fields in the three-scales is established, and the multi-phase finite element (MFE) method is adopted to overcome the difficulty in discretization for the heterogeneous structural models. The time-dependent stress relaxation responses under three-scales were particularly investigated by the coupling MFE-AEH multi-scale method. The time-dependent effective viscoelastic properties in the micro-sclae and meso-scale were also calculated by utilizing the Prony Series fitting to simplify the inverse Laplace transform. The accuracy and reliability are validated by the corresponding experimental and numerical results, the effects of braided angle and relaxation time on the viscoelastic properties of 3D braided composites were studied, respectively. (c) 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).