Vorhersage des Ermüdungsrissausbreitungsverhaltens von Aluminiumlegierungen für Beanspruchungen mit variablen Mittelspannungen

Abstract

For realistic lifetime predictions of cracked components the crack propagation behaviour under variable amplitude spectrum loads and for variable mean stress has to be known. Therefore a method on the basis of only two crack propagation experiments for the prediction of the crack propagation behaviour for variable mean stress was developed. Beside a crack propagation curve for a constant mean stress solely one further experiment, where the threshold was reached by an increase of the minimum stress level, was required. On the basis of this two investigations the threshold behaviour in dependence of the mean stress and the constants of the corresponding crack propagation calculation can be predicted. The procedure results in a self-contained function for the description of crack propagation curves for variable mean stress. The theoretical calculation was verified with experimental data of aluminium 6013 T62 and 2024 T351. It shows a very good correspondence to the experimental data. This results are an important basis for operational stability calculations of cracked components, especially for a load spectrum with variable mean stress. Further this method is an efficient possibility to investigate the complete crack propagation behaviour with variable mean stress.

Influence of Kmax and R on Fatigue Crack Growth—A 3D‐Model

“…To measure crack extension and to control the experiment a computer with proprietary software is used. A detailed description of the testing system, which is called ''ErikaErmü dungsrissausbreitung in korrosiver Atmosphäre'' (i.e., ''fatigue crack propagation in corrosive atmosphere''), and of the experimental options are described in the papers [2][3][4] . With the ERIKA system it is possible to control the stress intensity factor (K) during the experiments.…”