Accession Number : AD0872137

Title :   Mechanisms of Fatigue in Filament-Reinforced Metals.

Descriptive Note : Technical rept., 1 Apr 69-31 Mar 70,

Corporate Author : MIDWEST RESEARCH INST KANSAS CITY MO

Personal Author(s) : Hancock, J. R.

Report Date : MAY 1970

Pagination or Media Count : 49

Abstract : The mechanisms of low-cycle fatigue were studied in composites of aluminum reinforced with 34 vol. % of continuous beryllium filaments. Two series of composite specimens were tested, one series fabricated using as-drawn (rough surfaces) beryllium wire and another using electropolished (smooth surfaces) beryllium wire, to determine the effects of mechanical interlock at the filament-matrix interface on fatigue performance. Axial, strain-controlled fatigue tests were performed. The cyclic stress-strain curves were identical for the two series of composite specimens, while composites reinforced with as-drawn filaments exhibited longer fatigue lives than composites reinforced with electropolished filaments. This difference in fatigue lives between the two series of composites was attributed to the difference in the rate of crack growth parallel to filament-matrix interfaces. It was concluded that rough filament surfaces impede interfacial crack growth, and that interface conditions and the resistance of the matrix to crack growth are important considerations in the design of fatigue-resistant, filament-reinforced metals. (Author)

Descriptors :   (*COMPOSITE MATERIALS, FATIGUE(MECHANICS)), ALUMINUM, BERYLLIUM, FIBERS, MANUFACTURING, INTERFACES, ELECTRON MICROSCOPY, SURFACES.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE