This paper reviews on the use of the Modified Wöhler Curve Method (re-interpreted in terms of the Theory of Critical Distances) to predict the high-cycle fatigue strength of notched components subjected to fatigue loading. This method takes as its starting point the assumption that fatigue damage depends on all the physical phenomena taking place within the fatigue process zone (the so-called structural volume). The material volume controlling all the fatigue processes has a size which does not depend on the degree of multiaxiality of the stress field damaging critical sites, but its size is different for different materials. Assuming that crack initiation in the high-cycle fatigue regime is Mode II governed, the Modified Wöhler Curve Method must be applied by considering the linear-elastic stress state at the centre of the structural volume. The main advantage of this method is that it is based on the use of linear-elastic stresses: this aspect makes it suitable for being used to post-process results from linear-elastic Finite-Element models. Finally, accuracy and reliability of the proposed method was checked by using data taken from the technical literature: the Modified Wöhler Curve Method was seen to be a useful tool suitable for assessing mechanical components in situations of practical interest.
On the use of the Modified Wöhler Curve Method to Estimate Notch Fatigue Limits
SUSMEL, Luca
2006
Abstract
This paper reviews on the use of the Modified Wöhler Curve Method (re-interpreted in terms of the Theory of Critical Distances) to predict the high-cycle fatigue strength of notched components subjected to fatigue loading. This method takes as its starting point the assumption that fatigue damage depends on all the physical phenomena taking place within the fatigue process zone (the so-called structural volume). The material volume controlling all the fatigue processes has a size which does not depend on the degree of multiaxiality of the stress field damaging critical sites, but its size is different for different materials. Assuming that crack initiation in the high-cycle fatigue regime is Mode II governed, the Modified Wöhler Curve Method must be applied by considering the linear-elastic stress state at the centre of the structural volume. The main advantage of this method is that it is based on the use of linear-elastic stresses: this aspect makes it suitable for being used to post-process results from linear-elastic Finite-Element models. Finally, accuracy and reliability of the proposed method was checked by using data taken from the technical literature: the Modified Wöhler Curve Method was seen to be a useful tool suitable for assessing mechanical components in situations of practical interest.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
