ABSTRACT This document presents an interactive tool for notch fatigue analysis and life predictio... more ABSTRACT This document presents an interactive tool for notch fatigue analysis and life prediction. Modified Neuber's rule is used to determine notch-root elastic-plastic stress and strain. The effect of mean stress on fatigue crack initiation life is accounted by utilizing a deviatoric formulation of the Smith-Watson-Topper parameter. For variable amplitude loading a rainflow method is used and the corresponding hysteresis loops at the notch-root are determined. Then, the relevant interactive graphs and calculated values are displayed. The propose methodology is intended to be a comprehensive fatigue analysis tool used by any designer engineer in global market environment. A brief flow chart of the intended tool is presented here.
ABSTRACT The Smith-Watson-Topper (SWT) parameter was originally suggested and is still widely use... more ABSTRACT The Smith-Watson-Topper (SWT) parameter was originally suggested and is still widely used to account for mean stress effects in fatigue life analysis. It is well recognized however, that the SWT parameter might be non-conservative for cyclic loads that involve relatively large compressive mean stresses. Such large compressive mean stresses can develop in notches after overloads. An energy interpretation of the SWT parameter is presented first. Based on analogy with the Neuber’s rule a new deviatoric formulation of the SWTD parameter is proposed. It is found that for positive mean stresses and moderate negative mean stresses the original SWT parameter and the proposed deviatoric SWTD parameter yield similar results. At large compressive mean stresses and non-proportional biaxial fatigue, the deviatoric SWTD parameter demonstrates a fairly good correlation to test data while the original SWT parameter results in wide scatter.
A custom method to generate fatigue crack growth (FCG) data requires testing of multiple specimen... more A custom method to generate fatigue crack growth (FCG) data requires testing of multiple specimens at different load ratios, R, and the application of a load shedding procedure from pre-cracking level to threshold. In this paper, a novel method of testing has been investigated which ...
ABSTRACT This document presents an interactive tool for notch fatigue analysis and life predictio... more ABSTRACT This document presents an interactive tool for notch fatigue analysis and life prediction. Modified Neuber's rule is used to determine notch-root elastic-plastic stress and strain. The effect of mean stress on fatigue crack initiation life is accounted by utilizing a deviatoric formulation of the Smith-Watson-Topper parameter. For variable amplitude loading a rainflow method is used and the corresponding hysteresis loops at the notch-root are determined. Then, the relevant interactive graphs and calculated values are displayed. The propose methodology is intended to be a comprehensive fatigue analysis tool used by any designer engineer in global market environment. A brief flow chart of the intended tool is presented here.
ABSTRACT The Smith-Watson-Topper (SWT) parameter was originally suggested and is still widely use... more ABSTRACT The Smith-Watson-Topper (SWT) parameter was originally suggested and is still widely used to account for mean stress effects in fatigue life analysis. It is well recognized however, that the SWT parameter might be non-conservative for cyclic loads that involve relatively large compressive mean stresses. Such large compressive mean stresses can develop in notches after overloads. An energy interpretation of the SWT parameter is presented first. Based on analogy with the Neuber’s rule a new deviatoric formulation of the SWTD parameter is proposed. It is found that for positive mean stresses and moderate negative mean stresses the original SWT parameter and the proposed deviatoric SWTD parameter yield similar results. At large compressive mean stresses and non-proportional biaxial fatigue, the deviatoric SWTD parameter demonstrates a fairly good correlation to test data while the original SWT parameter results in wide scatter.
A custom method to generate fatigue crack growth (FCG) data requires testing of multiple specimen... more A custom method to generate fatigue crack growth (FCG) data requires testing of multiple specimens at different load ratios, R, and the application of a load shedding procedure from pre-cracking level to threshold. In this paper, a novel method of testing has been investigated which ...
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