Date of Award
Master of Science
Department of Aeronautics and Astronautics
Anthony N. Palazotto, PhD
Sandwich beams consisting of a carbon foam core and graphite/bismaleimide face sheets were constructed and tested. Nine specimens were fabricated using three distinct cross-ply symmetric face sheet layups with a constant core thickness. Four-point bend testing controlled by a constant rate of midspan vertical displacement was used to load the specimens to failure. Displacements and strains from the experiment were compared to analytical sandwich beam theory and displacements and failure loads were compared to a layerwise finite element solution. A phenomenological failure criterion was developed that compares favorably with experimental failure data. The finite element solution gives failure within an average of 7.58% of experiment and a stiffness within an average of 11.16%. The analytical sandwich beam theory predicts stiffness within 4.83% of experiment and strain within 5.27% of experiment. This research shows that the finite element theory has the ability to predict failure onset and location in a sandwich structure and that the face sheet layups within higher stiffness delay the onset of shear failure in the core.
DTIC Accession Number
Welker, Troy C., "Experimental and Computational Failure Analysis of Graphite/Bismaleimide Laminated Composite and Carbon Foam in Sandwich Construction" (2003). Theses and Dissertations. 4151.