Accession Number : AD0722009

Title :   The Initiation and Growth of Fatigue Cracks in Filament-Reinforced Aluminum Alloys.

Descriptive Note : Technical rept. 1 Apr 69-28 Feb 71,

Corporate Author : MIDWEST RESEARCH INST KANSAS CITY MO

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

Report Date : MAR 1971

Pagination or Media Count : 34

Abstract : The low-cycle fatigue behavior of filamentary composites of 1235 aluminum-beryllium, 6061 aluminum-beryllium, and 7075 aluminum-boron were compared. The effects of the strength and ductility of the filaments and matrix, and the role of interfaces on fatigue hardening, and on fatigue-crack initiation and growth were evaluated to develop guidelines for the design of fatigue-resistant composites. Generally, brittle filaments, a ductile matrix, weak interfacial bonds, and a large modulus difference between constituents are the factors which lead to greater fatigue resistance in filament-reinforced metals. The observed modes of fatigue-crack growth confirmed the theoretical predictions of the effects of stress distribution at a crack tip at an inferface, and extended the applicability of these predictions to filamentary composites. (Author)

Descriptors :   (*COMPOSITE MATERIALS, FATIGUE(MECHANICS)), (*ALUMINUM ALLOYS, COMPOSITE MATERIALS), FILAMENTS, BERYLLIUM, BORON, CRACK PROPAGATION, REINFORCING MATERIALS, CRACKS

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE