Multiaxial fatigue analysis of notched components using combined critical plane and critical distance approach

Abstract

Combinations of geometric discontinuities and multiaxial loads appear commonly in engineering components, which raise both stress gradient and multiaxial stress states near the notch root. This work studies the combined critical plane approach with the theory of critical distance for fatigue analysis of notched components under multiaxial loadings. Taking the Fatemi-Socie model for instance, different coupling sequence of critical plane and critical distance concepts is discussed. In particular, the influence of employing the point method and the line method of the theory of critical distance on predicting performance as well as the rationality of regarding the critical distance as a material constant or as a function related to fatigue life are also investigated. Accordingly, 8 life assessment procedures are summarized and the optimal procedure is determined and verified by experimental data of Al 7050-T7451 and GH4169 alloys. Results show that the majority of the predicted points fall within the ±2 scatter band according to experimental results and the procedures which employ the theory of critical distance after using the critical plane approach and regarding the critical distance as a function related to fatigue life provide better accuracy on fatigue life prediction than others.