Date of Award
Doctor of Philosophy (PhD)
Mechanical and Aerospace Engineering
Davidson, Dr. Berry D.
Aerospace Engineering | Engineering
The research conducted for this dissertation focused on understanding the nature and extent of barely visible impact damage (BVID) in composite sandwich structures. This was part of a larger research effort that included studies on the influence of BVID on the compressive strengths and failure modes of composite sandwich structures. In this dissertation, the nature and extent of BVID is studied in aluminum honeycomb core sandwich panels with eight and sixteen ply, quasi-isotropic, graphite/epoxy face sheets. The damage in the sandwich structure is created quasi-statically using spherical indentors of two different sizes. Apart from the face sheet thickness and indentor size, other parameters that are varied in the experimental investigations include the core thickness, core density and face sheet layup. The effects of these parameters on the nature and extent of damage in the sandwich structure is evaluated. The different damage metrics of dent diameter, dent depth and planar area of delamination are used for damage characterization and these damage metrics are evaluated non-destructively. The damage resistance of the different sandwich configurations based on these damage metrics is then assessed. It is shown that when the extent of damage in a sandwich structure is determined based on the dent depth or the dent diameter, the sandwich structure that uses a higher density core is the most damage resistant. However, when the extent of damage is based on the planar area of delamination, the parameters that govern the damage size differ for the different face sheet thicknesses. An analytical model is developed in this dissertation to predict the quasi-static load versus displacement response of the sandwich structure during loading, including the onset of damage and the subsequent unloading behavior. It is shown that the analytical model is capable of predicting the residual dent depth and the residual dent diameter of the sandwich structure for damage within the vicinity of BVID
Singh, Abhendra K., "Damage Characterization and Analytical Modeling of Quasi-statically Indented Graphite/Epoxy-Honeycomb Core Composite Sandwich Stru" (2013). Mechanical and Aerospace Engineering - Dissertations. 77.