Micromechanical stress analysis of closely packed fibrous composites

By considering variations in topology, material properties and adhesion characteristics, the micromechanical stress states developed within fibrous composites that contain a heterogeneous interphase region has been predicted numerically. The formulation of a generalized computational simulation developed to treat specific features of these materials yields stress predictions using a finite-element approximation. The parametric description of the geometry and the incorporation of material inhomogeneities by a sequence of homogeneous subregions allows for the treatment of any material combination including closely packed composites and conditions of imperfect adhesion. Considering square and hexagonal arrays of fibers, two major finite-element grids were generated where the features and the constrains are automatically being assigned. Numerical results illustrate the influence of material parameters on local critical stress states and indicate regions of high stress concentration. It has been proved that, fiber interaction substantially intensifies stress concentrations within the interphase region, although imperfect adhesion relieves stresses. (C) 2000 Elsevier Science Ltd. All rights reserved.