An investigation of a fatigue model with two competing failure mechanisms
2012 (English)Report (Other academic)
Fatigue limit tests where there are two competing fatigue failure locations, two notches of different size, are performed in this paper. The normal distribution is used for describing the experimental outcome, where the largest occurring stress value or the gradient adjusted stress is used as a stress measure. Another model for describing the experimental outcomeis the Weakest Link (WL)-integral where the integration is performed over the specimen surface area or the specimen volume. The longitudinal positions of the estimated fatigue failure sites are measured and investigated as well. Neither the normal distribution (point stress and gradient adjusted point stress), nor the WL-integral can explain the experimental outcome from the competing notch tests. They all predict the same trend, but not the same trend as in the experiments. When looking at the estimated longitudinal location of fatigue failure it can be seen that it differs considerably from experiment to experiment. If the stress is evaluated at the estimated fatigue failure location, it is seen that the local stress is much lower than the maximal stress. The load cases where there should be an equal amount of failures in both notches according to the different models do not agree with the experimental findings. It is concluded that stress based continuum models can not describe the experimental outcome when there are competing fatigue failure sites (notches) present.
Place, publisher, year, edition, pages
2012. , 19 p.
Trita-HFL, ISSN 1104-6813 ; 525
IdentifiersURN: urn:nbn:se:kth:diva-103858OAI: oai:DiVA.org:kth-103858DiVA: diva2:562005
QC 201210252012-10-252012-10-222012-10-26Bibliographically approved