The failure initiation site in the open-hole 10-degree off-axis specimen isexamined by means of an intrinsic flaw model. A distribution of intrinsic flawlengths is determined from experimental data for the strength and failure sitevariability of unnotched (no central circular hole), 10-degree off-axis specimens.Comparison between the intrinsic flaw length at the perimeter of the circular-holeand at the free-edge in the open-hole specimens indicated that the material at theperimeter of the circular-hole is more flaw-sensitive than at the free-edge and thusthe more likely site for failure-initiation.Additionally, the intrinsic flaw lengths at the perimeter of the circular-hole areshown to be similar in character to the intrinsic flaw lengths for the unnotchedspecimen. When the intrinsic flaw length is taken as a material constant, theperimeter of the circular-hole is clearly indicated as the failure initiation site. Thedistribution of intrinsic flaw lengths is then used to predict the strength variabilityof the unnotched and open-hole specimens in order to determine the flaw density ateach hole-size. Finally, the flaw density and distribution of intrinsic flaw lengthsare used to predict the failure site and strength of open-hole specimens when failureinitiation at the perimeter of the circular-hole and at the free-edge are bothconsidered. It is shown that failure initiation at the free-edge is rare or does notoccur, suggesting the perimeter of the circular-hole as the primary failure initiationsite for the open-hole off-axis tensile specimen.1
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