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:

1971-12-01

Pagination or Media Count:

119.0

Abstract:

Prestressing of boronepoxy 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