The present study is concerned with the use of the Modified Manson-Coffin Curve Method [1] to estimate lifetime of notched components subjected to multiaxial cyclic loading. In more detail, the above criterion postulates that fatigue strength under complex loading paths can efficiently be evaluated in terms of maximum shear strain amplitude, provided that, the reference Manson-Coffin curve used to predict the number of cycles to failure is defined by taking into account the actual degree of multiaxiality/non-proportionality of the stress/strain state damaging the assumed crack initiation site. The accuracy and reliability of the fatigue life estimation technique formalised in the present paper was checked by considering about 300 experimental results taken from the literature and generated by testing notched cylindrical samples made of four different metallic materials and subjected to in-phase and out-of-phase biaxial nominal loading. In order to more deeply explore the peculiarities of our criterion also the effect of non-zero mean stresses was studied in depth. To calculate the stress/strain quantities needed for the in-field use of the Modified Manson-Coffin Curve Method, notch stresses and notch strains were estimated by using not only the analytical tool due to Köttgen, Barkey and Socie [2] (applied along with the rule proposed by Jiang and Sehitoglu [3, 4]), but also by taking full advantage of the Finite Element (FE) method to perform some calibration analyses. Such a validation exercise allowed us to prove that our approach is successful in estimating lifetime of notched components failing in the low/medium cycle fatigue regime, resulting in estimates falling mainly within an error band of 3.
A simple and efficient reformulation of the classical Manson-Coffin curve to predict lifetime under multiaxial fatigue loading. Part II: notches
SUSMEL, Luca;
2009
Abstract
The present study is concerned with the use of the Modified Manson-Coffin Curve Method [1] to estimate lifetime of notched components subjected to multiaxial cyclic loading. In more detail, the above criterion postulates that fatigue strength under complex loading paths can efficiently be evaluated in terms of maximum shear strain amplitude, provided that, the reference Manson-Coffin curve used to predict the number of cycles to failure is defined by taking into account the actual degree of multiaxiality/non-proportionality of the stress/strain state damaging the assumed crack initiation site. The accuracy and reliability of the fatigue life estimation technique formalised in the present paper was checked by considering about 300 experimental results taken from the literature and generated by testing notched cylindrical samples made of four different metallic materials and subjected to in-phase and out-of-phase biaxial nominal loading. In order to more deeply explore the peculiarities of our criterion also the effect of non-zero mean stresses was studied in depth. To calculate the stress/strain quantities needed for the in-field use of the Modified Manson-Coffin Curve Method, notch stresses and notch strains were estimated by using not only the analytical tool due to Köttgen, Barkey and Socie [2] (applied along with the rule proposed by Jiang and Sehitoglu [3, 4]), but also by taking full advantage of the Finite Element (FE) method to perform some calibration analyses. Such a validation exercise allowed us to prove that our approach is successful in estimating lifetime of notched components failing in the low/medium cycle fatigue regime, resulting in estimates falling mainly within an error band of 3.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
