A multiscale approach to model fiber‐reinforced composites, those that are characterized by an isotropic orientation of fibers, is presented. To this end, a bottom‐up approach is used to formulate a hierarchical model. The primary basis for the mesoscopic description revolves around the assumption that the composite network consists of fibers resting on foundations of the native material matrix. Molecular dynamics (MD) simulations of such fibers on foundations are performed, and crucial material parameters, such as the stiffness of the particle matrix and Young's modulus of the fibers are evaluated. Subsequently, a micro‐mechanical constitutive model is formulated, wherein fiber‐reinforced composites are characterized by a homogeneous distribution and an isotropic orientation of fibers. The fibers are modeled as beams undergoing bending and stretching while resting on Winkler‐type of elastic foundations. The 3D macroscopic network behavior is finally presented. As an example, the particle matrix used is a silica aerogel and the fibers are modeled as double‐walled carbon nanotubes. In the proposed modeling approach, MD simulations are shown to provide a physical estimation of the micro‐mechanical model parameters.
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