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Liu Jianhui 1 and Wang Shengnan 1 and Jin Wuyin 2 and Gao Wen 1
Academic Editor:Pedro A. R. Rosa
1, School of Aeronautics, Northwestern Polytechnical University, Xi'an 710072, China
2, Institute of Electrical and Mechanical Engineering, Lanzhou University of Technology, Lanzhou 730050, China
Received 14 January 2014; Accepted 31 March 2014; 17 April 2014
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
All kinds of notches exist in mechanical structures which tend to produce stress concentration. Fatigue life prediction of notched components in complex service conditions requires the local stress-strain relationship of a material element at the notch-root to be known [1]. The notch stress-strain analysis and low-cycle fatigue concepts are often used in fatigue analysis to estimate crack initiation lives [2]. It is necessary to measure or calculate the local elastic-plastic notch-root stresses and strains in order to perform such analysis. In many situations, measurements are impractical or impossible. So the calculations are necessary. However accurate calculations of these stresses and strains are not intractable; they are difficult and lengthy especially for a long arbitrary cyclic loading. Therefore, approximate methods are widely used in engineering practice. So far, a few approximate methods for description of the nonlinear stress-strain behavior of notches have been developed [3]. Among these, the most popularly and frequently used relation is Neuber rule, which has been extended to fatigue problems [4]. However, in most cases Neuber rule overestimates the notch-root stresses and strains. An alternative method for predicting elastic-plastic notch-root strain, based on strain energy density considerations, has been proposed [5]. Contrary to Neuber rule, the equivalent strain energy density method tends to underestimate the plastic strain in notch-root. Both Neuber rule and the ESED method have been derived for simple stress states such as pure shear or plane stress. For notched bodies in plane strain, extensions of Neuber rule have been proposed by Hoffman et al. [6] and of the ESED method by Glinka [7]. However, neither simplified method has been successfully extended to address notched bodies subjected to a general multiaxial loading. As we all know that...