Analysis of fatigue behaviour of notched components

CHAPETTI, M.D.; STEIMBREGER C.

VALDIVIA

Congreso; CONAMET-SAM 2020; 2019

Universidad Austral de Chile - CONAMET

The assessment of fatigue damage in structures is of primary importance in industry. Since most components contain notches that act as local stress raisers, the evaluation of fatigue behaviour in these cases is even more relevant. However, notched members show a higher fatigue limit than the value obtained by means of the stress concentration factor, kt. The introduction of the fatigue notch factor, kf, has partially solved this issue and lead to plenty of models that describe relation between this quantity and kt. In general, they are based on empirical expressions that proved to be practical for designing, but they lack in scientific meaning. Some alternatives make use of Fracture Mechanics to develop theoretical correlations [1, 2] that were found to be very useful for understanding the basic damage mechanisms involved in the fatigue process. More detailed assessments were achieved by means of the Resistance Curve method [3], which aimed at including the short crack regime in the analysis. The resistance curve compares the driving force for crack propagation with the resistance of the material, or threshold for crack growth. Both quantities are defined in terms of crack length. It was discussed in previous publications by the authors [4] that these approaches are difficult to apply to unknown materials, since they are based on crack closure phenomenon. Due to this, threshold curve is obtained semi-empirically, using difficult procedures which are both time-demanding and scattered [5].In the present work, an Integrated Fracture Mechanics Approach (IFMA) is proposed to be applied to notched components in general.