Prediction of fatigue life of a notched body by the local stress-strain State. Part 3. Allowing for stress and strain gradients

We propose a method for calculating the fatigue life of bodies with stress concentrators prior to the fatigue-crack initiation. It is based on the energy criterion of fracture. Energy dissipated in a notch is taken as a determining parameter. The method allows the fatigue life of notched bodies under regular symmetrical loading to be predicted from the cyclic strain and fatigue characteristics of the material, as obtained in tests of smooth specimens. We analyze the influence of absolute dimensions of a stress concentrator on the fatigue life and propose relationships for calculating the gradients of dissipated energy and the residual strain amplitude. The data we obtained are compared with the test results for notched specimens of 30KhGSA steel and D16AT and AMtsM aluminum alloys. © 2000 Plenum Publishing Corporation.