2D finite elements for the analysis of fiber reinforced composites subjected to 3D stresses

A numerical model suitable for the prediction of the overall mechanical response of unidirectional fiber reinforced composites (FRCs) under any macroscopic stress condition has been developed. This model consists of a mesh of plane finite elements, with particular boundary conditions that account for the periodicity of the reinforcing array. The finite elements have been expressly developed to describe particular 3D microscopic displacement fields, associated with strain fields that do not vary along the fiber axis. Elements with the above features have been implemented in a commercial finite element code and employed to analyze elastic FRCs under general 3D stresses. The effectiveness of the proposed elements has been checked though comparisons with available experimental and theoretical results regarding the macroscopic thermoelastic properties of different FRCs. The model turns out to be definitely advantageous in comparison with fully 3D finite element models in terms of computing time and number of constraints to be accounted for to enforce the boundary conditions periodicity.