Local and non-local normalised equivalent strain functionals for cyclic fatigue

Abstract

The concept of Cyclic Normalised Equivalent Strain Functionals (CNESnFs) suitable for lowcyclic fatigue is developed in this paper. It reduces any fatigue strength and durability model to a unique form what facilitates the models comparison. Generalisation of some known fatigue durability models and introduction of new linear and nonlinear ones including those sensitive to the load sequence, are made. The functional concept allows to unite the strength and durability description under static, fatigue, creep and dynamic loading and their combinations. Examples of such new complex functional strength conditions are presented. The non-local versions of the CNESnFs applicable to strain fields sharply varying in space coordinates and to crack initiation and propagation analysis are also presented.