Digital Repository, ECF14, Cracow 2002

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Failure Mechanisms of Composite Sandwich Beams under Impact Loading

Last modified: 2013-02-10


An experimental investigation of the failure mechanisms of a compositesandwich beam under central low-velocity impact was undertaken. The beam was made ofunidirectional carbon/epoxy facesheets and various core materials including aluminumhoneycomb, balsa wood, polyurethane foam and foam-filled honeycomb. Damage of thebeam depended on the level of impact energy and the properties of the core material. Forlow impact energies, the impactor after reaching the specimen bounces transferring energyback to the impactor as kinetic energy. For higher energies core crushing coupled withbending of the upper facesheet took place. The upper facesheet deforms permanently withoutfailure. As the impact energy increases delamination of the facesheets or debondingbetween the core and the facesheets occurred. For much higher energies wrinkling or perforationof the upper facesheets was recorded. Damage was assessed by visual inspectionand photomicrographs taken in a microscope under various magnifications. Macroscopicand microscopic failure mechanisms were recorded. Macroscopic mechanisms include indentation,surface cracking, delamination and perforation. Microscopic mechanisms includefiber breakage and matrix cracking. Results concerning the mechanisms and damagedevelopment for various core materials and impact energies were obtained.

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