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.

PDF Url : ADA289420

Report Date : DEC 1994

Pagination or Media Count : 274

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/cu m (9 lb/cu ft), 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: (O/90)s, (O/9O)2s, (O/90)4s, (O/90)8s, and (O/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.

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