Analysis of the Second ASTM Round-Robin Program on Opening-Load Measurement using the adjusted compliance ratio technique
The results of the Second Round-Robin on Opening-Load Measurement established the basis for a recent addition to ASTM E 647--``Recommended Practice for Determination of Fatigue Crack Opening Load from Compliance''. The technique involves characterizing the deviation in linearity of a load-displacement curve and reporting, as a minimum, the opening load corresponding to a 2% slope offset. The opening load and associated {Delta}K{sub eff} values reported showed significant scatter although this scatter was reduced when the data were subjected to a rigorous accept/reject criterion. Refinements in the method of handling data with high noise have further reduced scatter compared with the original analysis. Since each participant provided digitized load-displacement curves, the data from 17 test samples (10 participants) were reanalyzed using the adjusted compliance ratio (ACR) technique to evaluate {Delta}K{sub eff}. A comparison between the two methods shows that the ACR technique gives a higher mean value of {Delta}K{sub eff} than does the ASTM procedure. The ACR technique also shows a stronger correlation with crack growth rate data than does the ASTM procedure, with a slope comparable to that of a typical fatigue crack growth rate test. However, the mean value of {Delta}K{sub eff} based on the ASTM procedure shows better agreement with high stress ratio closure free data than does the ACR technique. This seemingly contradictory result can be partially explained in terms of second-order effects not normally considered significant.
- Research Organization:
- Fracture Technology Associates, Bethlehem, PA (US)
- OSTI ID:
- 20005697
- Resource Relation:
- Conference: Second Symposium on Advances in Fatigue Crack Closure Measurement and Analysis, San Diego, CA (US), 11/12/1997--11/13/1997; Other Information: PBD: 1999; Related Information: In: Advances in fatigue crack closure measurement and analysis: Second volume. ASTM special technical publication 1343, by McClung, R.C.; Newman, J.C. Jr. [eds.], 490 pages.
- Country of Publication:
- United States
- Language:
- English
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