Chapter 50. Time-Dependent Strength Degradation and Reliability of an Alumina Ceramic Subjected to Biaxial Flexure

  1. John B. Wachtman Jr.
  1. Luen-Yuan Chao and
  2. Dinesh K. Shetty

Published Online: 28 MAR 2008

DOI: 10.1002/9780470314180.ch50

Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8

Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8

How to Cite

Chao, L.-Y. and Shetty, D. K. (1993) Time-Dependent Strength Degradation and Reliability of an Alumina Ceramic Subjected to Biaxial Flexure, in Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials, Part 1 of 2: Ceramic Engineering and Science Proceedings, Volume 14, Issue 7/8 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314180.ch50

Author Information

  1. Department of Materials Science and Engineering University of Utah Salt Lake City, UT 84112

Publication History

  1. Published Online: 28 MAR 2008
  2. Published Print: 1 JAN 1993

ISBN Information

Print ISBN: 9780470375266

Online ISBN: 9780470314180

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Keywords:

  • reliability;
  • randomly;
  • biaxial flexure tests;
  • dynamic;
  • parameters

Summary

Fracture stresses of a sintered alumina ceramic were assessed in qualified uniaxial (three- and four-point) and biaxial (uniform pressure-on-disk) flexure tests under inert conditions (dry N2, 100 MPa/s stressing rate) and in deionized water at a low stressing rate (1 MPa/s). The size and stress-state effects on the inert fracture stresses of the alumina ceramic could be explained by a reliability analysis based on randomly oriented surface flaws and a mixed-mode fracture criterion. The decreased fracture stresses measured in both uniaxial and biaxial flexure tests in water were consistent with subcritical crack growth behavior inferred from dynamic fatigue tests in water. The analysis of the size- and stress-state effects on and time-dependent degradation of fracture stresses for conservative assessment of reliability required consideration of the statistical uncertainty (90% confidence bands) in the fracture stress data and in the estimated parameters of the fracture stress distributions (Weibull modulus, m, and characteristic strength, s̀θ) and of the slow crack growth (stress-intensity exponent, N, and critical crack growth rate, Vc).