Impact-damage characterization in laminated composites

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5571227

Joshi, S P

Comprehensive studies of impact-induced fracture in laminated composites are lacking, largely because of the complexity of the problem. This research provides a starting point for a simple working model for an impact-induced fracture. An interactive study that uses a finite-element numerical analysis together with experimental observations is done. A three-layer cross-ply graphite epoxy laminate is initially chosen for both experimental and numerical studies. The studies done on cross-ply laminates are extended to quasi-isotropic laminates. Experimental data for the three-dimensional problem of impact of a flat strip by a spherical impactor are presented and interpreted qualitatively by comparison with a plane strain numerical analysis of an infinitely wide plate impacted by a cylindrical impactor. The role of transverse shear stress and flexural stress in damage initiation is established. A detailed presentation of damage is provided with exact delamination zones. Strain responses, using a plate finite element, are correlated with the experimental observations to provide a simple model for damage initiation in laminated composites. The results establish that the crack in the distal ply (opposite to the impact side) is produced when the transverse flexural strain in the ply reaches 9000 ..mu.. Strain in the impact zone.

• Research Organization: Purdue Univ., Lafayette, IN (USA)
• OSTI ID: 5571227
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360303* -- Composite Materials-- Mechanical Properties-- (-1987)
CARBON
COMPOSITE MATERIALS
DAMAGE
ELEMENTAL MINERALS
ELEMENTS
EPOXIDES
FRACTURE PROPERTIES
GRAPHITE
IMPACT TESTS
LAYERS
MATERIALS
MATERIALS TESTING
MEASURING METHODS
MECHANICAL PROPERTIES
MECHANICAL TESTS
MINERALS
NONMETALS
NUMERICAL SOLUTION
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
TESTING