Some Contributions to the Further Development of Low Cycle Fatigue Life Analysis Concepts for Notched Components under Variable Amplitude Loading

TLDR: In this article, the authors present the current state in the development of a new three-dimensional elastic-plastic FEM-based fatigue analysis concept, FEMFAT, using a material model according to MrOz's proposal, and the fatigue damage is calculated on the basis of the plastic work as performed at the fatigue critical locations of components.

Abstract: In order to minimize the expenses of the development of engineering components and to reduce the risk of their operation, reliable fatigue life prediction methods have to be available in the design stage. Presently two groups of methods can be distinguished which explicitly account for the local stresses/strains in the fatigue critical areas: the so-called notch analysis concepts or "local approaches," and new developments which are based on finite element methods (FEM). In the first part of the paper typical areas in application of the notch analysis methods and some aspects of their further development are described. The significance of the short crack stage is briefly characterized from a physical and an engineering point of view. In the second part the present state in the development of a new three-dimensional elastic-plastic FEM-based fatigue analysis concept, FEMFAT, is described. FEMFAT uses a material model according to MrOz's proposal, and the fatigue damage is calculated on the basis of the plastic work as performed at the fatigue critical locations of components. A calculation scheme for the damage increments under arbitrary out-of-phase loading based on uniaxial data is proposed. Two examples of the application of FEMFAT are given.