Fatigue design in the presence of stress concentrations

Abstract

This paper reports a comparative study of some recent methods developed for the estimation of high-cycle fatigue behaviour of components containing stress concentrations. It begins by reviewing some existing methods for the prediction of fatigue limits: the stress-life method, linear elastic fracture mechanics, the Kitagawa-Takahashi and Atzori-Lazzarin approaches and the method of Smith and Miller. Two new methods are described which have been developed during the last few years: the crack modelling method (CMM) and the critical distance method (CDM). These methods were tested by comparing their predictions with experimental data using a large database of 88 different notch geometries and materials. Notches were divided into three types: blunt, sharp and short. The CDM was found to be very successful for all types of notch, giving predictions within 20 per cent of experimental values in the great majority of cases. The CMM encountered difficulties with short notches; correction factors were developed to overcome this problem. Both methods can be used very easily in conjunction with finite element analysis, making them more useful than previous methods for the prediction of high-cycle fatigue in engineering components.