Fatigue life curve – A continuous Wöhler curve from LCF to VHCF

Abstract

Abstract In order to consider cyclic material behavior in the course of the design process of cyclically loaded components and safety relevant parts, the importance of local strain-based fatigue design approaches has been growing continually. For the damage impact of load-time histories on components such as chassis parts, standard service loads with amplitudes settled in the high cycle fatigue and very high cycle fatigue regimes as well as overloads and misuse with load amplitudes from the low cycle fatigue regime, have to be considered, in order to perform a reliable fatigue life estimation. Therefore, a continuous fatigue life curve from the LCF to the VHCF regime, which covers all relevant damage mechanisms, is required. Hence, a fatigue life curve from low cycle fatigue (LCF) across to high cycle fatigue (HCF), and culminating at very high cycle fatigue (VHCF), derived from a combined method using strain- and load-controlled fatigue tests, will be discussed. This continuous fatigue life curve for aluminum wrought alloys, based on the evolution of the behavior of elastic-plastic material as well as the results of high frequency testing up to VHCF, will be presented.