Accession Number : ADA301743

Title :   Toughening of Graphite-Epoxy Composites by Interlaminar Perforated Mylar (trade name) Films.

Descriptive Note : Technical memo.,

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

Personal Author(s) : Elber, Wolf

PDF Url : ADA301743

Report Date : MAR 1978

Pagination or Media Count : 16

Abstract : Fracture and notch-strength tests of graphite-epoxy composites have shown that unidirectional lay-ups generally exhibit longitudinal cracking before failure, whereas multidirectional lay-ups fail transversely with little longitudinal cracking. A simple qualitative analysis suggested that the higher matrix shear stresses in unidirectional materials cause the longitudinal cracking, and that this cracking is responsible for the higher toughness of unidirectional composites. In a series of comparative tests, the interlaminar strength of multidirectional composites was reduced by placing perforated Mylar films between laminae; tests on notched and slotted specimens showed that the inter-laminar films promoted delamination and longitudinal cracking near the notches and that, as a result, toughness, notch strength, and impact strength were substantially increased. (MM)

Descriptors :   *LAMINATES, *POLYESTER PLASTICS, *GRAPHITE EPOXY COMPOSITES, MATERIALS, COMPOSITE MATERIALS, CRACKS, FIBER REINFORCED COMPOSITES, COMPOSITE STRUCTURES, TOUGHNESS, STRENGTH(MECHANICS), FRACTURE(MECHANICS), IMPACT STRENGTH, EPOXY RESINS, LAMINAR FLOW, DELAMINATION, UNIDIRECTIONAL, NOTCH SENSITIVITY.

Subject Categories : Laminates and Composite Materials
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE