Correction of the Poisson effect in the elastic analysis of low-cycle fatigue

Abstract

The amount of fatigue damage is very dependent on the cyclic variation in real strain. It is the current practice to use elastic analysis to assess this strain. In low-cycle fatigue conditions, in which inelastic strains are predominant, elastic analysis underestimates the real value of the variation in strain. To make effective use of the results of elastic analysis despite this shortcoming, corrections need to be made. One such correction concerns the Poisson effect, since Poisson's ratio vis higher for inelastic behaviour. In this paper a method for correcting the Poisson effect in the plastic range is proposed. It consists simply of multiplying the result of the elastic computation by a coefficient Kv. A method is developed for determining this coefficient as a function of the result of the elastic computation. It relies on simple analytical calculations and uses the uniaxial cyclic curve of the material. Examples are provided. The proposed procedure is easy to use and very inexpensive.