scholarly journals Studies on the Fatigue Crack Propagation Rate (1 st Report)

1980 ◽  
Vol 1980 (147) ◽  
pp. 219-229
Author(s):  
Junkichi Yagi ◽  
Yasumitu Tomita ◽  
Yukio Fujimoto
2008 ◽  
Vol 144 ◽  
pp. 90-93 ◽  
Author(s):  
Grzegorz Gasiak ◽  
Grzegorz Robak

The paper presents a test stand for measurements of fatigue crack propagation. The stand includes a fatigue machine MZGS–100 and a device for registration of the crack length. The test stand is equipped with a stereoscopic microscope with fluent magnification of 7× – 67.5×. The microscope can be applied for observation of fatigue crack development. The microscope is also equipped with a digital camera, which enables continuous observation of fatigue crack development on the computer monitor and it is not necessary to stop the machine. The test results obtained at this stand can be used for determination of fatigue life and fatigue crack propagation rate.


2007 ◽  
Vol 348-349 ◽  
pp. 377-380 ◽  
Author(s):  
Pavel Hutař ◽  
Luboš Náhlík ◽  
Zdeněk Knésl

The influence of corner singularity on the distribution of the stresses around the crack front for a three-dimensional structure is described in this paper. The distribution of stress singularity through the thickness of the middle tension specimen provides us an indication of crack behaviour close to a free surface. An estimation of the region where the change of singularity exponent plays an important role in fatigue crack propagation rate was carried out. A decrease in fatigue crack propagation rate close to the free surface was found. The lower fatigue crack propagation rate in the boundary layer in comparison with the interior of the specimen leads to a change of intersecting angle between crack and free surface and depends on Poisson’s ratio.


1979 ◽  
Vol 101 (2) ◽  
pp. 162-167 ◽  
Author(s):  
Shuji Taira ◽  
Ryuichi Ohtani ◽  
Tomio Komatsu

On the basis of the successful results of our previous study on a J-integral approach to the creep crack propagation of steels, the applicability of the creep J-integral to the time dependent fatigue crack propagation in creep range was studied. A satisfactory correlation was obtained between crack propagation rate and creep J-integral, and the same correlation was found in creep crack propagation under constant load as well as two-step loading. It was also found that the cycle dependent fatigue crack propagation rate could be successfully correlated by the cyclic J-integral. The high crack propagation rate in large scale yielding fatigue may be in agreement with the straight line extrapolation on log-log plots of the linear elastic fatigue crack propagation rate versus cyclic J-integral data.


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