A Study of Failure Characteristics in Thermoplastic Composite Laminates Due to an Eccentric Circular Discontinuity

The purpose of this thesis was to determine both experimentally and analytically the initiation and progression of failure, stress-strain response, and the failure loads of GraphitePolyetheretherketone GrPEEK laminates, incorporating an eccentric 0.4 inch circular discontinuity, loaded in axial tension at room temperature. For each ply lay-up, three values of eccentricity were considered the three values of eccentricity were determined by the hole location within each specimen. In addition, experimentation was conducted to study the effects of boundary conditions on the failure characteristics of the GrPEEK laminates this was accomplished through the use of a special mounting fixture which allowed in-plane rotation of the specimens. Finally, experimentation was conducted, using photoelasticity, to verify the gross stress states of the GrPEEK laminates predicted by the analytical study. Analytically, a nonlinear material finite element program was used to predict the initiation and progression of failure, stress-strain response, and the failure loads of the GrPeek laminates. In addition, the effects of boundary conditions on the failure modes of the GrPeek laminates was studied analytically. And finally, the gross stress states of the GrPEEK laminates were considered in the analytical portion of this thesis.