Mechanisms of cyclic fatigue-crack propagation in a fine-grained alumina ceramic: The role of crack closure

被引:25
作者
Gilbert, CJ
Ritchie, RO
机构
[1] Dept. of Mat. Sci. and Mineral Eng., University of California, Berkeley
关键词
D O I
10.1111/j.1460-2695.1997.tb01502.x
中图分类号
TH [机械、仪表工业];
学科分类号
0802 ;
摘要
Cyclic fatigue-crack growth and resistance-curve behavior have been studied in a fine-grained (similar to 1 mu m), high-purity alumina. Specific emphasis is given to the mechanisms associated with crack growth that are controlled by the maximum (K-max) and the alternating (Delta K), stress intensities and to the role of crack-face interference (crack closure), which is known to be an important crack-tip shielding mechanism in metal fatigue. Significant levels of subcritical crack growth were detected above a threshold stress intensity of similar to 60% of the fracture toughness (K-c) in the alumina, with growth rates displaying a far larger dependence on K-max compared to Delta K. The role of crack closure was examined using constant-K-max experiments, where the minimum stress intensity (K-min) was maintained either above or below the stress intensity for crack closure (K-cl). Where K-min < K-cl, growth rates were found to exhibit a lower dependence on Delta K, which was rationalized in terms of the frictional wear model for crack growth in grain-bridging ceramics. It is concluded that crack closure, as conventionally defined, has little relevance as a crack-tip shielding mechanism during fatigue-crack growth in grain-bridging ceramics, due to the low dependence of growth rates on Delta K compared to K-max.
引用
收藏
页码:1453 / 1466
页数:14
相关论文
共 41 条
[1]  
[Anonymous], ASTM STP
[2]  
[Anonymous], FATIGUE THRESHOLDS
[3]  
[Anonymous], 1984, FATIGUE CRACK GROWTH
[4]   CYCLIC FATIGUE-CRACK GROWTH IN SILICON-NITRIDE - INFLUENCES OF STRESS RATIO AND CRACK CLOSURE [J].
CHOI, G .
ACTA METALLURGICA ET MATERIALIA, 1995, 43 (04) :1489-1494
[5]   A FRICTIONAL-WEAR MECHANISM FOR FATIGUE-CRACK GROWTH IN GRAIN BRIDGING CERAMICS [J].
DAUSKARDT, RH .
ACTA METALLURGICA ET MATERIALIA, 1993, 41 (09) :2765-2781
[6]   CYCLIC FATIGUE-CRACK GROWTH IN A SIC-WHISKER-REINFORCED ALUMINA CERAMIC COMPOSITE - LONG-CRACK AND SMALL-CRACK BEHAVIOR [J].
DAUSKARDT, RH ;
JAMES, MR ;
PORTER, JR ;
RITCHIE, RO .
JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 1992, 75 (04) :759-771
[7]  
DAUSKARDT RH, 1989, CLOSED LOOP, V17, P7
[8]  
Elber W., 1970, Engineering Fracture Mechanics, V2, P37, DOI 10.1016/0013-7944(70)90028-7
[9]  
Erdogan F., 1963, J. Basic Eng., V85, P528, DOI [DOI 10.1115/1.3656900, 10.1115/1.3656900]
[10]   DYNAMIC FATIGUE CRACK-GROWTH IN POLYCRYSTALLINE ALUMINA UNDER CYCLIC COMPRESSION [J].
EWART, L ;
SURESH, S .
JOURNAL OF MATERIALS SCIENCE LETTERS, 1986, 5 (08) :774-778