A micromechanics-based finite element model for compressive failure of notched uniply composite laminates under remote biaxial loads

A micromechanics based failure initiation predictive capability for analyzing notched composite laminates loaded remotely in multiaxial compression is reported. The model relies on the results from a previous experimental study that investigated compression failure mechanisms in special "uniply" composite laminates. The finite element method (FEM) was used in the solution process. The experimental results showed that the dominant mode of failure initiation was kink banding near the hole edge. The kink band was confined in extent to a distance within one half of the hole radius. The fibers within the kink band were rotated both in plane and out of the plane of the laminate. The position of the kink band with respect to the center of the notch depended on the remote biaxial load ratio. In the FEM, the region in which kink banding takes place is contained within a finite size rectangular area, and is meshed as an alternatingly stacked region of fiber and matrix layers. The values of boundary loads on this rectangular area which correspond to kink banding is related to the remotely applied loads via an available closed form analysis for orthotropic laminates. Good agreement is found between experiment and analysis for a wide range of notch sizes.