Fatigue or cyclic loads require two load parameters for unambiguous description. Under SN fatigue this expresses as Load Ratio or mean stress effects, illustrated by Goodman et al more than 100 years ago and expressed in Haigh Diagrams. However under fatigue crack growth (FCG), researchers considered only Delta K and invoked an extrinsic parameter called crack closure to account for the R-ratio effects. We have developed a Unified approach and published extensively to show that DK and Kmax can uniquely describe the FCG without the need of crack closure measurements. Of the five parameters, DK, Kmax, R, Kmean, and Kmin only two are independent, charactering FCG behavior. Prof. Greg Glinka has developed a UNIGROW life prediction model based on our approach. I think it is high time to develop New ASTM standard based on the two parametric approach without the need of crack closure. We have also accounted the short crack growth (see our recent review in Met. Sci Eng.) without the need of invoking a similitude breakdown. Attached is recent analysis of data on steels where the original authors showed that plasticity induced crack closure could not account disparity near thresholds and they had to invoke Oxide induced crack closure to account for the material response. We have analyzed that data without need of any crack closure and we could develop the crack growth trajectories for the two steels. There are many other examples in our papers.

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