Accession Number:

ADA289420

Title:

An Experimental Investigation of Sandwich Flat Panels Under Low Velocity Impact.

Descriptive Note:

Master's thesis,

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s):

• Harrington, Timberlyn M.

Report Date:

1994-12-01

Pagination or Media Count:

274.0

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 kgcu m 9 lbcu ft, 3.175 mm 18 in. cell size Nomex honeycomb core, FM 300-2 film adhesive and AS43501-6 graphiteepoxy 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 O90s, O9O2s, O904s, O908s, and O9012s. 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.

Descriptors:

• *IMPACT STRENGTH
• *GRAPHITE EPOXY COMPOSITES
• *SANDWICH PANELS
• STRESS STRAIN RELATIONS
• THICKNESS
• COMPOSITE MATERIALS
• LAMINATES
• IMPACT TESTS
• CRACKING(FRACTURING)
• DAMAGE ASSESSMENT
• THESES
• COMPOSITE STRUCTURES
• STRAIN(MECHANICS)
• BENDING
• LOW VELOCITY
• BUCKLING
• DROP TESTS
• FAILURE(MECHANICS)
• STACKING
• ADHESIVES
• DELAMINATION
• POISSON RATIO
• HONEYCOMB CORES
• CRUSHING

Subject Categories:

• Laminates and Composite Materials
• Structural Engineering and Building Technology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE