Multiscale image-based modeling of progressive damage in 3D5D braided composites with yarn-reduction

The special-shape fiber-reinforced composites are improbable to be represented by the representative volume element (RVE). Hence, a multiscale image-based model is proposed to reveal the progressive damage in 3D5D braided composites with/without yarn-reduction. The microscale and mesoscale models of the materials are reconstructed by Micro-CT, considering the yarns’ twists, global compression, and yarns’ misalignment. Subsequently, the continuous damage method and the cohesive-zone model are proposed to characterize the damage behavior of the microscale and mesoscale constituents. These constitutive models are implemented by a user-defined subroutine UMAT in ABAQUS. Finally, based on the homogenization procedure and the multiscale analysis method, the effects of structures on microscale, mesoscale, and macroscale properties of 3D5D braided composites without/with yarn-reduction are analyzed sequentially. The results show that cross-section variations and twists in the yarns modify the damage initiation. The wedge-shaped stress migration phenomenon occurs near the yarn-reduction point. Besides, the macroscopic simulation of strain fields and the damage morphology agrees well with the DIC measurements and Micro-CT results. The established multiscale framework is expected to predict the progressive damage of 3D5D braided composites with/without yarn-reduction and provide the theoretical basis for the structure design.