Nonlinear Analytical Approach for Preliminary Sizing of Discrete Composite Stringer Terminations

Arecently developed nonlinear approach is adapted and used to predict crack initiation in stringer terminations of discretely assembled composite panels made from skin and stiffeners. A linear elastic fracture mechanics based submodel is used to simulate the crack initiation in the critical regions and the influence of ply drop-off is captured. The von Karman formulation for moderately large deflections in plates is used to capture the nonlinear structural behavior; three-dimensional assemblies are schematized and the effect of eccentricity is included in the simulation. An optimum design criterion is sought and basic guidelines for good design are provided. Furthermore, a method for preliminary assessment of structural strength is proposed and predictions are validated against detailed nonlinear finite element analysis. [PUBLICATION ABSTRACT]