Date of Award

12-1994

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Anthony N. Palazotto, PhD

Second Advisor

Greg Schoeppner, PhD [AFRL]

Abstract

This study evaluated the failure modes and mechanisms associated with increasing face sheet thickness of flat sandwich panels under low velocity impact. The sandwich panels were fabricated using 1.27 cm thick, 145 kg-m3 (9 lb-ft3), 3.175 mm (1-8 in.) cell size Nomex honeycomb core, FM 300-2 film adhesive and AS4-3501-6 graphite-epoxy face sheets. The thickness of the core remained 1.27 cm, and the thickness of the adhesive remained 0.25 mm. The thickness of the face sheets varied using the following stacking sequences: [0-90]s, [0-90]2s, [0-90]4s, [0-90]8s, and [0-90]12s. The sandwich panels were subjected to various low velocity impacts using the Dynatup Impact Test Machine. Pulse-Echo C-scans and optical microscopy of panel cross-sections were performed to characterize the damage. The cross-sections indicated that delamination and transverse cracking contribute to internal damage of the face sheets, while crushing, buckling, and crippling contribute to damage of the core. Cracks in the adhesive also contribute to damage in some cases.

AFIT Designator

AFIT-GAE-ENY-94D-22

DTIC Accession Number

ADA289420

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