Research On Stress-Strain Analysis And Life Predictions For Notched Specimens Under Multiaxial Loading

In this paper,the stress-strain analysis and life prediction for the notched shafts were studied under multiaxial constant amplitude proportional loading.First, literature review showed that mutiaxial fatigue theory is increasingly attracted attentions by some scholars in the world. However, multiaxial fatigue is more complicated than uniaxial fatigue, and is limited by the experimental aspects. Up to now, many problems have not been solved completely, especially for notched machine components. For multiaxial life prediction, the critical plane approach is better than that of others, however, the accuracy of life prediction is deeply influenced by the results of stress-strain analysis.Second, a few methods presented by some scholars were used to calculate the elasto-plastic strains and stresses at the notch tip subjected to proportional loading. At the same time, a new method is proposed to calculate the stresses and strain for the same specimen. The results proved that the proposed new method is practicable. Third, finite element analyses have been carried out for a notched shaft under proportional bending and torsional loading. The result is very accurate if the appropriate element and mesh are selected. With the development of computer technology, finite element method will be widely used.Finally, two new methods of multiaxial fatigue life prediction were presented by the analysis of the stress-strain and damage parameters on multiaxial fatigue damaged critical planes. To some extent, it has a clear physical significance due to taking into account of the two main parameters on the critical planes. The predicted life by using the two new methods and the observed life are compared for a notched shaft. The results showed that the presented new methods are reasonable.