Failure criteria for fibrous composites based on multiscale modeling

Abstract

Failure criteria were proposed to describe physics-based failure modes of the fibrous composite at its micro-scale level. The criteria consist of four failure modes at the constituent material level, and they are: fiber breakage, fiber buckling, matrix cracking, and fiber/matrix interface debonding. The failure criteria for these failure modes were expressed in terms of stresses and strains at the micro-scale, i.e., those occurring within the fiber and matrix materials. To determine the micro-scale stresses and strains and to apply the failure criteria to the macro-scale composite material, a multiscale analysis was employed. The multiscale analysis links the micro-scale and macro-scale using the unit cell approach. The unit cell can compute the macro-scale (i.e., effective) material properties from the micro-scale (i.e., constituents) material properties. In addition, the unit cell can also compute micro-scale stresses and strains from macro-scale stresses and strains. The proposed failure criteria can be used for composite structures such as laminated fibrous composites, woven fabric composites, etc., The criteria were applied to multiple example cases under combined loading, which had available experimental data, to assess their reliability. The prediction using the proposed failure criteria agreed well with the experimental data.