Experimental Mechanics

, Volume 44, Issue 4, pp 425–432 | Cite as

Effects of measurement techniques on the experimental characterization of crack tip opening angle-Δa resistance curves

  • W. Burton
  • S. Mahmoud
  • K. Lease


One of the most promising approaches to characterizing the stable tearing process for lower constraint configurations in metallic materials has been indicated to be the crack tip opening angle (CTOA) criterion. In this paper we examine the effect of measurement distance selection and the impact of measurement procedures/analysis on the experimental CTOA-Δa resistance curve behavior of a Ti-6Al-4V and an Al5083 alloy. A new, systematic procedure for carrying out the experimental, surface CTOA measurement process has been used, which has uncovered artifacts of measurement distance selection that have not been presented prior to this study. By studying the CTOA-Δa behavior using a rigidly defined and consistent method, it is apparent that the measurement distance behind the crack tip at which angles are measured has a direct impact on the shape of the early transitional behavior of the CTOA-Δa behavior as well as the critical, experimental CTOA values produced.

Key Words

Stable tearing fracture crack tip opening angle CTOA Ti-6Al-4V Al5083 



critical, experimental crack tip opening angle


compact tension specimen


crack length after pre-cracking


specimen width


maximum to minimum load ration for fatigue pre-cracking


crack length extension beyondai


crack tip opening angle measurement distance behind the crack tip


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Copyright information

© Society for Experimental Mechanics 2004

Authors and Affiliations

  • W. Burton
    • 1
  • S. Mahmoud
    • 1
  • K. Lease
    • 1
  1. 1.Department of Mechanical and Nuclear EngineeringKansas State UniversityManhattanUSA

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