Advertisement

Experimental Mechanics

, Volume 53, Issue 2, pp 163–170 | Cite as

Automated Control of Stable Crack Growth for R-Curve Measurements in Brittle Materials

  • H. Jelitto
  • F. Hackbarth
  • H. Özcoban
  • G. A. Schneider
Article

Abstract

Stable crack advance is required for a reliable crack growth resistance (R-Curve) measurement. In bending experiments, manual control of the mechanical load and observation of the growing crack is still being done by the operator. This work presents an approach to partly and fully automated R-curve measurements, where stable crack growth is achieved solely via computer control. The experimental setup in conjunction with an intelligent control algorithm leads to reliable results, even for brittle materials like alumina ceramics, silicon nitride, and glass. Furthermore, it allows for a novel type of measurement, because the device detects any kind of energy release in the specimen, actually also without visible crack extension. The setup has been used successfully for about 3 years. The operating principle is explained and some of the results are presented exemplarily. The method is realized in 4-point-bending, but can be implemented also for other types of specimen and loading to automatically achieve stable crack growth.

Keywords

Fracture toughness R-curve Automation 4-point-bending Stable crack growth 

References

  1. 1.
    Cullen WH, Landgraph RW, Kaisand LR, Underwood JH (1985) Automated test methods for fracture and fatigue crack growth. ASTM Publ, Code Number (PCN) 04-877000-30Google Scholar
  2. 2.
    Fett T, Fünfschilling S, Hoffmann MJ, Oberacker R, Jelitto H, Schneider GA (2008) R-curve determination for the initial stage of crack extension in Si3N4. J Am Ceram Soc 91(11):3638–3642CrossRefGoogle Scholar
  3. 3.
    Fünfschilling S, Fett T, Hoffmann MJ, Oberacker R, Jelitto H, Schneider GA (2009) Determination of the crack-tip toughness in silicon nitride ceramics. J Mater Sci 44:335–338CrossRefGoogle Scholar
  4. 4.
    Özcoban H, Jelitto H, Schneider GA (2010) Influence of finite notch root radius and optically determined crack length on the measured fracture toughness of brittle materials. J Eur Ceram Soc 30(7):1579–1583CrossRefGoogle Scholar
  5. 5.
    Özcoban H, Salikov V, Jelitto H, Schneider GA (2012) Experimental crack front investigation of unpoled soft lead Zirconate Titanate (PZT) using the Single Edge V-Notched Beam (SEVNB) method. Exp Mech. doi: 10.1007/s11340-012-9599-z (online available)
  6. 6.
    Özcoban H, Fett T, Schneider GA (2012) Computer-controlled stable crack growth as a reliable and fast method to determine subcritical crack growth. J Test Eval 40/2Google Scholar
  7. 7.
    Jelitto H, Felten F, Swain MV, Balke H, Schneider GA (2007) Measurement of the total energy release rate for cracks in PZT under combined mechanical and electrical loading. J Appl Mech 74:1197–1211CrossRefGoogle Scholar
  8. 8.
    Xia SM, Gao YF, Bower AF, Lev LC, Cheng Y-T (2007) Delamination mechanism maps for a strong elastic coating on an elastic–plastic substrate subjected to contact loading. Int J Solids Struct 44:3685–3699zbMATHCrossRefGoogle Scholar
  9. 9.
    Munz D, Fett T (1999) Ceramics – mechanical properties, failure behaviour, materials selection. Springer, BerlinGoogle Scholar
  10. 10.
    Kübler J (1998) Bestimmung der Bruchzähigkeit keramischer Werkstoffe mit der SEVNB Methode: Resultate eines VAMAS/ESIS Ringversuches. Proc Werkstoffwoche, EMPA. Dubendorf, SwitzerlandGoogle Scholar
  11. 11.
    Kübler J (2001) Fracture toughness of ceramics using the SEVNB method: from preliminary study to a standard test method. Fracture resistance testing of monolithic and composite brittle materials, ASTM STP 1409, eds. Salem JA, Jenkins MG, and Quinn GD, Am Soc Test Mater, West Conshohocken, PAGoogle Scholar
  12. 12.
    Lucato SL, Lupascu DC, Rödel J (2000) Effect of poling direction on R-curve behavior in lead zirconate titanate. J Am Ceram Soc 83/2:424–426Google Scholar
  13. 13.
    Davidge RW, Tappin G (1968) The effective surface energy of brittle materials. J Mater Sci 3:165–173CrossRefGoogle Scholar

Copyright information

© Society for Experimental Mechanics 2012

Authors and Affiliations

  • H. Jelitto
    • 1
  • F. Hackbarth
    • 2
  • H. Özcoban
    • 1
  • G. A. Schneider
    • 1
  1. 1.Institute of Advanced CeramicsHamburg University of TechnologyHamburgGermany
  2. 2.Institute of AutomationHamburg University of TechnologyHamburgGermany

Personalised recommendations