Accession Number : ADA195604

Title :   Modeling of Micromechanisms of Fatigue and Fracture in Hybrid Materials.

Descriptive Note : Annual rept. no. 1, 15 Apr 87-14 Apr 88,

Corporate Author : CALIFORNIA UNIV BERKELEY DEPT OF MATERIALS SCIENCE AND MINERAL ENGINEERING

Personal Author(s) : Ritchie, R O ; Yu, W ; Siu, S C

PDF Url : ADA195604

Report Date : May 1988

Pagination or Media Count : 59

Abstract : The obvious benefits of the design of aerospace structures using lighter materials with high specific strengths and stiffness has led in recent years to the development of numerous reinforced composite materials, which have become serious commercial competitors to traditional monolithic metallic alloys. While significant advances in processing technology have made the fabrication of such hybrid materials more of an economic reality, their widespread use in airframes or other critical structures has in general been limited by serious deficiencies in particular mechanical properties, such as ductility, toughness and fatigue. This problem is often compounded by the lack of fundamental studies which provide a rational basis for the underlying sources of crack-propagation resistance in these materials, and in particular which define the critical role of composite microstructure. Accordingly, the current program is aimed at studying the physics and micromechanisms of fracture toughness and particularly the fatigue-crack growth resistance in laminate, discontinuously-reinforced and continuously-reinforced metal-matrix composites, with special reference to the role of microstructure. Keywords: Fatigue(Mechanics); Fracture toughness; Subcritical crack growth; Metal-Matrix; Composites; Laminates; Fatigue cracks; Crack closure; Crack bridging; Aluminum alloys; Magnesium alloys; Crack propagation. (jes)

Descriptors :   *FATIGUE(MECHANICS), *FRACTURE(MECHANICS), *HYBRID SYSTEMS, AEROSPACE CRAFT, AIRFRAMES, ALUMINUM ALLOYS, BRIDGES, CLOSURES, COMPOSITE MATERIALS, CRACK PROPAGATION, CRACKS, DUCTILITY, LAMINATES, MAGNESIUM ALLOYS, MATERIALS, MECHANICAL PROPERTIES, MICROSTRUCTURE, PHYSICS, PROCESSING, REINFORCING MATERIALS, RESISTANCE, SOURCES, STIFFNESS, STRENGTH(GENERAL), STRUCTURES, SUBCRITICAL ASSEMBLIES, TOUGHNESS

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE