Accession Number : ADA302017

Title :   Effects of Partial Interlaminar Bonding on Impact Resistance and Loaded-Hole Behavior of Graphite/Epoxy Quasi-Isotropic Laminates.

Descriptive Note : Technical memo.,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER

Personal Author(s) : Illg, Walter

PDF Url : ADA302017

Report Date : JUL 1986

Pagination or Media Count : 48

Abstract : An interlaminar weakening concept that was developed to improve fracture toughness of composites was evaluated for its effects on resistance to impact and for behavior around a loaded hole. Mylar sheets with 25- and 15-percent perforations were interleaved between 24 composite prepreg layers. Specimens were impacted by 13-mm-diameter aluminum spheres while under tensile or compressive loads. Failure thresholds and residual strengths were obtained. The loaded-hole specimens were tested in three configurations: bearing critical, shear critical, and tension critical. Ultrasonics and X-radiography were used to detect damage. The tensile and compressive strengths of undamaged specimens were reduced by 36 and 30 percent, respectively, by partial bonding. Partial bonding reduced by 50 percent the velocity of impact that could be survived while under compression. Also under compression, the prestrain threshold level for failure was about one-half that under tension for all bonding percentages. Little benefit of partial bonding was uncovered for tension, and serious degradation occurred for compression.

Descriptors :   *LAMINATES, *GRAPHITE EPOXY COMPOSITES, TENSILE STRENGTH, DEGRADATION, STRESS ANALYSIS, IMPACT TESTS, DISPLACEMENT, MODULUS OF ELASTICITY, BEARING STRENGTH, STRAIN(MECHANICS), STRENGTH(MECHANICS), FRACTURE(MECHANICS), IMPACT STRENGTH, HOLES(OPENINGS), BONDING, FAILURE(MECHANICS), COMPRESSIVE STRENGTH, ELONGATION, AXIAL LOADS, COMPRESSIVE PROPERTIES, POISSON RATIO, BEARING CAPACITY.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE