A unit-cell approach to prediction of the microbuckling strength of composites with non-uniform fiber imperfections under combined axial compression and in-plane shear

A new micromechanical model for predicting the failure locus of long fiber composites under combined axial compression and in-plane shear is proposed. The model is based on a periodic unit cell with centrally located imperfections. Predictions of the compressive behavior for various biaxial loading ratios are made. The role of distribution of fiber imperfections in predicting the biaxial strength is discussed. The failure locus calculated from the new model is found to be in good agreement with experimental data available in the literature and less conservative than that from the periodic model with uniform imperfections.