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Small-Crack Behavior and Safety-Critical-Design Criteria for Cyclic Fatigue in Mg-PSZ Ceramics

Research output: Chapters, Conference Papers, Creative and Literary WorksRGC 32 - Refereed conference paper (with host publication)peer-review

Abstract

Cyclic fatigue-crack behavior is studied in a Mg-PSZ ceramic heat treated by sub-eutectoid aging to K1c toughnesses in the range 2.9 MPa√m (overaged) to 16 MPa√m (TS grade). S/N data, derived from unnotched cantilever-beam specimens, show markedly lower lives under tension-compression compared to tension-tension loading; "fatigue limits'' (108 cycles) for tension-compression loading approach 50% of the tensile strength of the material. When "long'' (>3 mm) fatigue crack propagation is examined, crack growth rates are found to be power-law dependent on the stress intensity range, ΔK, and to show evidence of a threshold stress intensity range, ΔKTH, approximately equal to 50% K1c. Conversely, for naturally occurring "small'' (<100 μm) surface cracks, fatigue crack growth is seen to occur at applied ΔK levels some two to three times smaller than the long crack threshold, ΔKTH. The implications of such small crack growth behavior on safety-critical-design criteria for ceramic components is discussed.
Original languageEnglish
Title of host publicationCyclic Deformation, Fracture, and Nondestructive Evaluation of Advanced Materials
EditorsM. R. Mitchell, Otto Buck
PublisherASTM
Pages69-81
ISBN (Print)0803114443
DOIs
Publication statusPublished - Nov 1990
Externally publishedYes
EventSymposium on Cyclic Deformation, Fracture, and Nondestructive Evaluation of Advanced Materials - San Antonio, United States
Duration: 12 Nov 199013 Nov 1990

Publication series

NameASTM Special Technical Publication
Volume1157
ISSN (Print)1040-3094

Conference

ConferenceSymposium on Cyclic Deformation, Fracture, and Nondestructive Evaluation of Advanced Materials
PlaceUnited States
CitySan Antonio
Period12/11/9013/11/90

Research Keywords

  • ceramics
  • zirconia
  • Mg-PSZ
  • long crack
  • transformation toughening
  • cyclic fatigue
  • design criteria
  • advanced materials
  • fatigue (materials)

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