OS2120 Measurement of Small Fatigue Crack Opening Stress Magnetostriction

2014 ◽  
Vol 2014 (0) ◽  
pp. _OS2120-1_-_OS2120-3_
Author(s):  
Yosuke SUZUKI ◽  
Yoshihito KUROSHIMA
Keyword(s):  
Fatigue Crack ◽  
Crack Opening ◽  
Small Fatigue Crack ◽  
Crack Opening Stress

scholarly journals A Novel Methodology for Calculating Crack Opening Stress under Tension-Compression Cyclic Load

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Lin Zhang ◽  
Xiaohui Wei
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Crack Opening ◽  
Compressive Load ◽  
Load Effect ◽  
Compression Load ◽  
Fatigue Crack Growth Life ◽  
Crack Opening Stress

Crack closure model has been used in several applications on the prediction of fatigue crack growth life, with expression of crack opening stress often serving as milestones. A typical difficulty in calculating the crack opening stress is the phenomenon of crack closure caused by the compressive load effect. Compressive load effect, resulting in the change of residual stress status at the unloading stage and the decrease of crack opening stress, is a long-term challenge for predicting fatigue crack growth life. We propose the expression of crack opening stress to predict fatigue crack growth life based on the analysis of compact tensile specimen with elastoplastic element method. It combines the characteristics of material and load to deal with the phenomenon of crack closure and uses stress ratio and normalized maximum applied load variable to construct the expression of crack opening stress. In the study of tensile-compression fatigue crack growth experiments, the proposed expression is proved to improve, by comparative analysis, the predictive ability on the whole range of experiment data. The novel expression is accurate and simple. Consequently, it is conducive to calculate the crack opening stress under tension-compression load.

Analysis on Fatigue Crack Growth Rates Under a Wide Range of Stress Ratios

1986 ◽  
Vol 108 (2) ◽  
pp. 209-213 ◽  
Author(s):  
M. Kurihara ◽  
A. Katoh ◽  
M. Kawahara
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Stress Ratio ◽  
Crack Opening ◽  
Wide Range ◽  
Stress Ratios ◽  
Crack Opening Stress ◽  
Crack Growth Rates

In the present study, a series of fatigue crack growth tests were carried out in order to examine the effects of stress ratio R upon crack growth rates, together with the crack closure behaviors. Fatigue tests were conducted with center-notched specimens of two kinds of pressure vessel steels (500 MPa class and 800 MPa class) under cyclic axial loading in various stress ratios R ranging from −5 to +0.8. Crack opening stress levels were determined by the unloading elastic compliance method. An expression of fatigue crack growth rates under a wide range of stress ratios was proposed, taking into account the relationship between stress ratio R and crack opening stress ratio U. The crack growth behaviors near the threshold conditions were also discussed.

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