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 analyzi ng notched composite laminates loaded remotely in multiaxial compression is reported. The model relies on the results from a previous experimental stu dy that investigated compression failure mechanisms in special "uniply" com posite 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 with in the kink band were rotated both in plane and out of the plane of the lam inate. The position of the kink band with respect to the center of the notc h depended on the remote biaxial load ratio. In the FEM, the region in whic h kink banding takes place is contained within a finite size rectangular ar ea, and is meshed as an alternatingly stacked region of fiber and matrix la yers. The values of boundary loads on this rectangular area which correspon d to kink banding is related to the remotely applied loads via an available closed form analysis for orthotropic laminates. Good agreement is found be tween experiment and analysis for a wide range of notch sizes.