Skip to main content
SpringerLink
Log in

Experimental evidence of crack tip shielding mechanisms in quasi-brittle materials

  • Published:
Journal of Materials Science Aims and scope Submit manuscript

Abstract

To gain insight into the shielding processes in quasi-brittle materials, in situ crack propagation and crack profile measurements were performed inside the scanning electron microscope (SEM). Crack tip shielding phenomena were studied in monolithic alumina and in SiC fibre-reinforced alumina matrix composites as a function of fibre coatings. The crack in the fibre-reinforced composite samples is bridged by a row of fibres which contains a fibre area fraction of 10%. The applied stress intensity factor necessary to extend the crack in the composite materials increased 25% for the gold coated fibre-reinforced alumina matrix composites and 13% for the polymer-coated fibre-reinforced composites, compared to the monolithic samples. Crack extension in the monolithic samples and in the fibre-reinforced composites occurred after the crack opening displacements close to the crack tip approached the critical crack tip profile corresponding to the intrinsic toughness of alumina. A hypothesis on the effect of closure stresses on crack profile shape and net toughness has been developed. Furthermore, crack profiles revealed that grain bridging in the vicinity of the fibres was operative in the fibre-reinforced composites at stress intensity factors far exceeding the critical stress intensity factor of the monolithic matrix material. The additional grain bridging in the vicinity of the fibres has never been reported and can only be revealed through crack profile measurements.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. Y. W. MAI and B. R. LAWN, J. Amer. Ceram. Soc. 70 (1987) 289.

    Article  CAS  Google Scholar 

  2. P. L. SWANSON, C. J. FAIRBANKS, B. R. LAWN, Y. W. MAI and B. J. HOCKEY, ibid. 70 (1987) 279.

    Article  CAS  Google Scholar 

  3. G. VEKINIS, M. F. ASHBY and P. W. BEAUMONT, Acta Metall. 38 (1990) 1151.

    Article  CAS  Google Scholar 

  4. S. T. BENNISON and B. R. LAWN, ibid. 37 (1989) 2659.

    Article  CAS  Google Scholar 

  5. P. CHANTIKUL, S. J. BENNISON and B. R. LAWN, J. Amer. Ceram. Soc. 73 (1990) 2419.

    Article  CAS  Google Scholar 

  6. D. B. MARSHALL and A. G. EVANS, ibid. 68 (1985) 225.

    Article  CAS  Google Scholar 

  7. D. B. MARSHALL, B. N. COX and A. G. EVANS, Acta Metall. 33 (1985) 2013.

    Article  Google Scholar 

  8. P. F. BECHER, J. Amer. Ceram. Soc. 73 (1991) 255.

    Article  Google Scholar 

  9. P. F. BECHER, E. R. FULLER, JR. and P. ANGELINI, ibid. 74 (1991) 2131.

    Article  CAS  Google Scholar 

  10. C. P. OSTERTAG, J. Amer. Ceram. Soc. in press.

  11. Idem., Comp. Engng 5 (1995) 1317.

    Article  CAS  Google Scholar 

  12. J. RODEL, J. F. KELLY, M. R. STOUDT and S. J. BENNISON, Scanning Microsc. 5 (1991) 29.

    Google Scholar 

  13. B. N. COX, Acta Metall. 39 (1991) 1189.

    Article  Google Scholar 

  14. H. TADA, P. C. PARIS and G. R. IRWIN, “The Stress Analysis Handbook” (Paris Productions (and Del Research Corp.) St. Louis, MO, 1985) Chapter 2.

    Google Scholar 

  15. P. CHANTIKUL, S. J. BENNISON and B. R. LAWN, J. Amer. Ceram. Soc. 73 (1990) 2419.

    Article  CAS  Google Scholar 

  16. G. R. IRWIN, in “Handbuch der Physik”, Vol. 6 edited by S. Flugge (Springer Verlag, Berlin, 1958) p. 551.

    Google Scholar 

  17. D. B. MARSHALL and B. N. COX, Acta Metall. 35 (1987) 2607.

    Article  CAS  Google Scholar 

  18. H. H. XU, C. P. OSTERTAG, L. M. BRAUN and I. K. LLOYD, J. Amer. Ceram. Soc. 77 (1994) 1899.

    Google Scholar 

  19. Idem., ibid. 77 (1994) 1897.

    Article  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Civil and Environmental Engineering, University of California, Berkeley, CA, 94720, USA

    C. P Ostertag

Authors
  1. C. P Ostertag
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Ostertag, C.P. Experimental evidence of crack tip shielding mechanisms in quasi-brittle materials. Journal of Materials Science 32, 4011–4017 (1997). https://doi.org/10.1023/A:1018685303978

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1023/A:1018685303978

Keywords

Search

Navigation