Three‐dimensional FE model for fiber interaction effects during microbuckling in composites with isotropic and anisotropic fibers

A three-dimensional finite element model is proposed for the fiber interaction effects during fiber microbuckling in fiber-reinforced composites. The model considers an elastic matrix reinforced by a periodic fiber series subjected to compression in axial direction. It accounts for the distinct difference in mechanical properties of the reinforcement and the matrix, as well as for the spatial problem character at the fiber-matrix scale. Perfect bonding at the fiber-matrix interfaces and the periodicity of the buckled system in the plane of fibers (in-plane microbuckling) are assumed. For comparison purposes, a dilute approximation model dealing with a single fiber in a matrix is presented as well. An eigenvalue analysis of the considered systems fiber-matrix is performed. Calculations are carried out for the cases of both isotropic and transversal isotropic fibers in elastic isotropic matrices. Results show that the fiber interaction results in a significant increase in the buckling wavelength and in an important decrease in the critical shortening.