SYMPOSIA PAPER Published: 01 January 1986

An Empirical Surface Crack Solution for Fatigue Propagation Analysis of Notched Components


A stress intensity factor solution for a surface crack in a finite solid subjected to an arbitrary stress field is presented. The solution was developed based on the superposition principle, the weight function technique, and a referenced finite body correction factor. An additional surface factor is identified when the solution is applied to the reduction of data from tests on surface flaw specimens.

Verification of the solution is first made by comparison with published results for problems with non-uniform stresses. The examples include a surface crack under pure bending load and a corner crack at a circular hole.

Another assessment was achieved by verifying the solution against the test results of ASTM round-robin test data for cracked fastener holes. Good correlation was obtained on all aspects of experimental observations such as the backtracked stress intensity factors, the measured residual lives, and the observed variation in crack aspect ratio.

It has been further demonstrated, from Air Force supported test programs, that the solution is accurate in predicting crack propagation behavior and residual life for subcomponent specimens under complex loadings. The test specimens are made of four different superalloys in various shapes of geometric discontinuities. The test conditions include various combinations of temperature, stress level, mean stress, and cycle profiles. The results have shown that the great majority of the measured life/predicted life ratios are within a factor of 1.5. It has also been demonstrated that the capability of the methodology is independent of the stress levels, specimen types, materials, and cycle profiles used in the study.

Author Information

Yau, JF
General Electric Company, Evendale, OH
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Developed by Committee: E08
Pages: 601–624
DOI: 10.1520/STP17419S
ISBN-EB: 978-0-8031-4972-4
ISBN-13: 978-0-8031-0472-3