Accession Number : AD0716629

Title :   Longitudinal Strength of Unidirectional Fibrous Composites.

Descriptive Note : Final technical rept. Jan 68-Feb 70,

Corporate Author : TECHNION - ISRAEL INST OF TECH HAIFA DEPT OF MATERIALS ENGINEERING

Personal Author(s) : Lifshitz,Jacob M. ; Rotem,Assa

Report Date : SEP 1970

Pagination or Media Count : 94

Abstract : Theoretical and experimental investigation of the longitudinal strength ofunidirectional fiber reinforced composite has been performed. The fibers aretreated as having variable strength which results in fiber fractures prior tocomposite failure. The matrix is treated as a linear viscoelastic material.The size effect is included in the mathematical analysis and the proposedfailure mechanism agrees with observed failure geometry. The effect of lengthon strength is found to be very small. Unidirectional glass reinforced epoxyand reinforced polyester specimens with 60% VOLUME FRACTION OF FIBERS WERETESTED IN TENSION AT THREE TEMPERATURES (25 C, 78 C AND 130 C) and a widetime range; from creep (more than a month) to impact tests. The compositestrength under impact conditions was found to be about three times higherthan under static conditions. This increase in strength is due to the glassfibers, the strength of which is rate sensitive. Scattering of results is quitehigh (plus or minus 10% in strength values, and plus or minus 5% in modulivalues) and this is attributed to the structure of the composite materials.(Author, modified-PL)

Descriptors :   (*COMPOSITE MATERIALS, MECHANICAL PROPERTIES), (*REINFORCING MATERIALS, *FIBERS), (*REINFORCED PLASTICS, MECHANICAL PROPERTIES), VISCOELASTICITY, GLASS TEXTILES, POLYESTER PLASTICS, EPOXY RESINS

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE