Mechanism of mechanical fatigue of fused silica: Progress report, January 1, 1986-November 30, 1986

Technical Report · Mon Dec 01 04:00:00 EST 1986

OSTI ID:7224765

Tomozawa, Minoru

The mechanical strength of glass is strongly influenced by crack geometry. A different fatigue mechanism has to be invoked depending upon whether the crack tip is sharp or blunt; a sharp tip crack can simply propagate, but a blunt tip crack has to be sharpened before it can propagate. It was shown that the crack tip of glass becomes blunt upon annealing. Similarly, the formation if a blunt crack was demonstrated earlier for glass specimens treated in hot water. Next, effects of the crack tip blunting on both dynamic fatigue and static fatigue were investigated in various liquids. It was found that fatigue of specimens with sharp cracks can be explained by the slow crack growth model satisfactorily, but fatigue of specimens with blunt cracks involves the initiation of a sharp crack in addition to the crack propagation. In static fatigue this crack initiation was found to require a far longer time than the crack propagation does. Furthermore, it was found that sharp crack initiation from a blunt tip under subcritical stress is possible only in water and not in non-aqueous liquids. Microhardness of glass in various liquids was investigated, and it was discovered that water enters SiO/sub 2/ glass during indentation while non-aqueous liquids do not.

• Research Organization: Rensselaer Polytechnic Inst., Troy, NY (USA). Dept. of Materials Engineering
• DOE Contract Number: FG02-85ER45217
• OSTI ID: 7224765
• Report Number(s): DOE/ER/45217-2; ON: DE87003794
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ANNEALING
CHALCOGENIDES
CRACK PROPAGATION
CRACKS
FATIGUE
GLASS
HEAT TREATMENTS
MECHANICAL PROPERTIES
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SILICA
SILICON COMPOUNDS
SILICON OXIDES