Accession Number : AD0919963

Title :   Increasing Strengths of Boron Fiber and Graphite Fiber Plastic Composites.

Descriptive Note : Final rept. May-Dec 71,

Corporate Author : NORTHROP CORPORATE LABS HAWTHORNE CA

Personal Author(s) : Mills, George J. ; Wochos, W. M. ; Brown, Gary G.

Report Date : DEC 1971

Pagination or Media Count : 119

Abstract : Prestressing of boron/epoxy prepreg tape material yields com-posites with substantial improvements in both average tensile strength and standard deviation over that obtained with conven-tional prepreg to laminate processing. The process has a fundamental effect on the prepreg fiber strength properties by prebreaking the fibers at their weak sites, and these induced changes are then carried into the composite as a reduction in property dispersion. The effects of processing parameters are evaluated by characterizing the details in the fiber strength distributions. The induced changes in fiber strength distri-bution are correlated with the composite strength properties. Prestressing essentially performs a quality control function on commerical type prepreg by reducing the inherent variability of unprocessed material. Fracture mode control has also been demonstrated for boron/ polyimide systems by a laminating method of alternating layers of resin rich and fiber rich prepreg mater-ial. (Author, modified-PL)

Descriptors :   (*COMPOSITE MATERIALS, STRENGTH(MECHANICS)), (*EPOXY RESINS, COMPOSITE MATERIALS), (*BORON, COMPOSITE MATERIALS), (*GRAPHITE, COMPOSITE MATERIALS), (*PRESTRESSING, COMPOSITE MATERIALS), REINFORCING MATERIALS, LAMINATES, SYNTHETIC FIBERS, POLYIMIDE RESINS, MANUFACTURING, MECHANICAL PROPERTIES, TENSILE PROPERTIES, MATRIX MATERIALS, FILAMENTS, FAILURE(MECHANICS), INTERFACES, TAPES.

Subject Categories : Laminates and Composite Materials
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE