Chapter 60. Specimem Geometry Effect on the Determination of Slow Crack Growth Parameters of Advanced Ceramics in Constant Flexural Stress-Rate Testing at Elevated Temperatures

  1. Ersan Ustundag and
  2. Gary Fischman
  1. Sung R. Choi1 and
  2. John P. Gyekenvesi2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470294567.ch60

23rd Annual Conference on Composites, Advanced Ceramics, Materials, and Structures : A: Ceramic Engineering and Science Proceedings, Volume 20, Issue 3

23rd Annual Conference on Composites, Advanced Ceramics, Materials, and Structures : A: Ceramic Engineering and Science Proceedings, Volume 20, Issue 3

How to Cite

Choi, S. R. and Gyekenvesi, J. P. (1999) Specimem Geometry Effect on the Determination of Slow Crack Growth Parameters of Advanced Ceramics in Constant Flexural Stress-Rate Testing at Elevated Temperatures, in 23rd Annual Conference on Composites, Advanced Ceramics, Materials, and Structures : A: Ceramic Engineering and Science Proceedings, Volume 20, Issue 3 (eds E. Ustundag and G. Fischman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294567.ch60

Author Information

  1. 1

    Cleveland State University, Cleveland, OH 44115

  2. 2

    NASA Lewis Research Center, Cleveland, OH 44135

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1999

ISBN Information

Print ISBN: 9780470375631

Online ISBN: 9780470294567

SEARCH

Keywords:

  • logarithm;
  • ceramic;
  • crack shape;
  • parameter;
  • reliability

Summary

The effect of specimen sizes on the determination of slow crack growth (SCG) parameters of advanced ceramics in constant flexural stress-rate testing at elevated temperature was investigated by using both experiments and numerical analysis. The SCG parameters were ocnsistent regardless of specimen sizes, either ASTM “A” size, ASTM “B” size, or wide thin plate specimens. The two-dimensional numerical solutions showed that the change in crack shape into an ellipse for thin small specimens was significant particularly at lower stress rates. Notwithstanding the significant change in crack shape together with appreciable crack growth comparable to the specimen dimensions, the difference in SCG parameters between the infinite and the finite bodies was insignificant (less than 1 %). This was due to the extremely long incubation time of an initial crack, unique to most advanced ceramics subjected to constant stress-rate testing. The conventional simple solution of strength as a function of stress rate can be used without compromising accuracy for any specimen sizes specified in ASTM C1211.