A Review for Methods of Determination of Fatigue Crack Growth Threshold

The methods of determination of fatigue crack growth (FCG) theoretical threshold ΔK thT are reviewed and summed up, with emphasis on the three approaches to deduction of ΔK thT from da/dN～ΔK test data by using FCG rate descriptions. The approaches are evaluated by four sets of test data for 2219-T851 aluminum alloy. It has been shown that the approaches of this type will lead to almost identical results so long as the descriptions can correctly reflect the regular pattern of FCG within near-threshold region and the da/dN～ΔK test data that are used to fit the descriptions include enough near-threshold data points.