Digital Repository, Giornata IGF Forni di Sopra (UD) 2011

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Multiaxial stress versus stress intensity factor based approaches to estimate short crack arrest in fretting fatigue
J.A. Araújo, F.C. Castro

Last modified: 2011-02-25


The aim of this paper is to carry out a comparative analysis between a multiaxial stress and a stress
intensity factor based criterion to estimate short crack arrest in fretting fatigue. The stress-based model involves
the computation of a multiaxial parameter at a critical distance from the contact. The critical distance is
identified by means of standard fatigue tests, namely two plain fatigue tests and the threshold test for long crack
propagation. The fracture mechanics model compares the mode I stress intensity factor range at a critical
distance from the contact with the threshold stress intensity for crack propagation. In this case, the critical
distance is defined as the crack transition length between the short and long crack regimes, which is obtained
from the Kitagawa-Takahashi diagram. In order to carry out a comparative analysis between the models, fretting
fatigue tests were conducted. A cylinder on plane contact configuration, both made of an Al 7050-T7451
aeronautical alloy, was considered. Twelve tests were performed with the same experimental conditions except
the mean bulk load, which varied from a tensile to a compressive value until a run out condition was achieved.
Results showed that the multiaxial fatigue approach is more accurate than the stress intensity factor based one
to estimate fretting fatigue limit for this alloy. The potentialities and limitations of both models in practical
applications are discussed.

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