Finite Element Methods for the Frequency Response Prediction of Bonded Composite Structures

The present study examines the effect bonded lap joints have on the frequency response of a given structure. The test article developed consist of carbon fiber composite sections joined with epoxy single-lap joints. The motivation for this study stems from the initial findings of previous works conducted at the Air Force Research Laboratory. This work shows the key factors affecting the influence of bonded lap joints on the system frequency to be: section stiffness, bond configuration and type, boundary conditions, and mass distribution. In addition, sensitivity analyses conducted give direction to the level of detail necessary to model bonded lap joints with adequate efficiency and accuracy. To aid in determining an effective and accurate methodology, the following sensitivity studies are conducted: element formulation, composite ply angle, and mesh discretization. Validation of these studies with experimental data for various configurations allow for an uncertainty assessment of the numerical data presented.