Micromechanical Analysis of Unidirectional Fiber-reinforced Composites

Physical testing of composites to determine their elastic and strength properties is difficult owing to their inherent heterogeneous character. Multiscale analysis presents a sequential approach to the prediction of these properties at micro, meso and macro levels for 2D laminates and 3D composites. The homogenized properties at any length scale are always derived from the well-defined properties of the constituent phases of the composite. The micromechanical analysis of the repetitive unit cells (RUCs), along with the periodic boundary conditions, initiates the computation of homogenized properties of the composites. In this paper, different types of RUCs have been identified and appropriate periodic boundary conditions are formulated to determine the homogenized properties of the composites which can be further used for meso and macro-mechanical analyses. An algorithm based on the available literature is used to generate the random distribution of unidirectional fibers and check for their compatibility. In the random fiber generation, two types of models have been analyzed, the first is the random fiber unit cell with periodicity, and the second is without considering any periodicity at the edges of the RUC. This also leads to the evolution of a representative volume element (RVE). This paper also attempts to inspect the progressive degradation in properties of a debonded unidirectional composite by using contact criteria at the fiber-matrix interface.