Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
770634 | Engineering Fracture Mechanics | 2015 | 22 Pages |
Abstract
Investigation of the deleterious effect of high purity water vapor on fatigue crack growth rate (da/dN) in 7075-T651 shows that growth rate declines with decreasing water vapor pressure (PH2O) over a wide range of stress intensity range (ΔK). Decreasing ΔK experiments exhibit a novel minimum in da/dN for intermediate PH2O and low ΔK. This minimum and testing protocol dependent environmental-fatigue behavior are explained by crack wake fracture morphology and R-dependent crack opening displacement effects on molecular flow to the crack tip. This environmentally-based mechanism leads to the onset and reversal of a non-conservative and false high threshold stress intensity range.
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Authors
J.T. Burns, R.W. Bush, J.H. Ai, J.L. Jones, Y. Lee, R.P. Gangloff,