Hierarchical micromechanical modeling for CNT-coated fuzzy fiber composites accounting for viscoplasticity and interfacial damage

This study investigates fuzzy fiber composites, characterized by a viscoplastic matrix and fuzzy fibers, i.e. fibers coated with radially aligned carbon nanotubes (CNTs). A comprehensive micromechanical framework is developed to model and optimize these composites, with a particular emphasis on interfacial damage mechanisms introduced through microvoids growth in the region between the fuzzy fibers and the matrix. By developing an equivalent fiber model, the complexity of the multi-phase structure is effectively reduced, facilitating efficient parametric analyses. Various homogenization techniques, including Composite Cylinder Assemblage (CCA), Transformation Field Analysis (TFA), and periodic homogenization, are combined to predict the overall stress–strain responses of the equivalent fiber approach and then the full fuzzy fiber composite. The identification of the framework and model parameters enabled a parametric/sensitivity analysis to study the effect of varying key parameters, including the volume fraction. The results of this paper contribute to a deeper understanding of unidirectional fuzzy fiber composites and establish a foundation for future parametric investigations and fuzzy fiber composite applications accounting for nonlinear regimes. • Multiscale framework for nonlinear fuzzy fiber composites. • Hybrid technique combining full-field and mean-field homogenization strategies. • Accounting for matrix viscoplasticity and interfacial damage. • At microscale the matrix-CNTs medium has transversely isotropic viscoplastic behavior. • Equivalent fiber approach using micromechanics and Transformation Field Analysis.