Mean stress effect on Gafiner curves interpreted as shifted Wohler curves and application to smooth and notched geometries

摘要

Recently, the authors proposed the simple idea that Gaßner curves can be interpreted as shifted Woehler curves if the Palmgren-Miner rule is applied. The idea is extended here to the general case of nonzero mean stress fatigue loading applied to smooth or notched specimens. The mean stress effect has been addressed through the corrections proposed by Smith-Watson-Topper and by Walker. In this way, a new expression for the shift factor G has been obtained. Through the application of the theory of the critical distances in its point variant, G is demonstrated to be valid for both smooth and notched geometries. A comparison with the Society of Automotive Engineers (SAE) Keyhole test program data is added to substantiate the findings.