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Cyclic fatigue-crack propagation in ceramics: Long and small crack behavior

Conference ·
OSTI ID:5294101
; ;  [1]
  1. Lawrence Berkeley Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

Stress/life (S/N) and cyclic fatigue-crack growth properties are studied in a Mg-PSZ, with particular reference to the role of crack size. S/N data from unnotched specimens show markedly lower lives under tension-compression compared to tension-tension loading; fatigue limits'' (at 10{sup 8} cycles) for the former case approach 50% of the tensile strength. Under tension-tension loading, cyclic crack-growth rates of long'' (> 3 mm) cracks are found to be power-law dependent on the stress-intensity range {Delta}K with a fatigue threshold, {Delta}K{sub TH}, of order 50% K{sub c}. Conversely, naturally-occurring small'' (1 to 100 {mu}m) surface cracks were observed to grow at {Delta}K levels some 2 to 3 times smaller than {Delta}K{sub TH}. The implications of such data for structural design with ceramics is briefly discussed. 21 refs., 3 figs., 1 tab.

Research Organization:
Lawrence Livermore National Lab., CA (United States)
Sponsoring Organization:
DOE; USDOE, Washington, DC (United States)
DOE Contract Number:
AC03-76SF00098
OSTI ID:
5294101
Report Number(s):
LBL-28243; CONF-900764--3; ON: DE92000899
Country of Publication:
United States
Language:
English