scholarly journals Hydrogen-Assisted Fatigue Propagation in Corner Cracks at Holes Located in Plates under Tensile Loading

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 552
Author(s):  
Jesús Toribio ◽  
Beatriz González ◽  
Juan-Carlos Matos
Keyword(s):  
Numerical Modeling ◽  
Stress Intensity ◽  
Crack Growth ◽  
Corrosion Fatigue ◽  
Crack Front ◽  
Stress Concentrator ◽  
Tensile Loading ◽  
Propagation Path ◽  
Intensity Factors ◽  
Corner Cracks

In this study, hydrogen-assisted fatigue propagation (a kind of corrosion fatigue phenomenon) in corner cracks at holes located in plates under tensile loading was studied, the results compared with those obtained for propagation by fatigue in air. To this end, numerical modeling was carried out for the case studied to evaluate the advance of the crack front based on the Paris equation and the stress intensity factors (SIFs) obtained by Raju and Newman. The results showed that the cracks tended toward a preferential propagation path in their growth, the effect of the presence of the stress concentrator on the preferential fatigue propagation path being more pronounced in the crack growth by fatigue in air than in the crack growth by corrosion fatigue.

Growth of Corner Cracks at a Hole

1982 ◽  
Vol 104 (2) ◽  
pp. 107-114 ◽  
Author(s):  
A. F. Liu ◽  
H. P. Kan
Keyword(s):  
Growth Rate ◽  
Stress Intensity ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Stress Intensity Factors ◽  
Crack Size ◽  
Crack Growth Behavior ◽  
Intensity Factors ◽  
Open Hole ◽  
Corner Cracks

The two-dimensional growth characteristics of corner cracks emanating from an open hole were demonstrated by conducting constant amplitude cyclic crack growth tests on a set of 51 specimens. The specimens were machined from 2024-T851 aluminum alloy in three thicknesses (6.35, 12.7, and 19.30 mm) and three hole diameters (6.35, 12.7, and 19.05 mm). The precrack sizes are very small (typically 0.5 to 1.0 mm in either length or depth dimensions) having many arbitrary initiated length-to-depth ratios. Empirical stress intensity factors for various crack size, crack shape, and specimen geometry combinations were calibrated by back-tracking of the crack growth rate behavior in these specimens and the material baseline crack growth rate data (also in three thicknesses of the same heat) developed from compact specimens. Superposition principles were applied to separate the lumped stress intensity factors into a parametric functional form. It has been demonstrated that these empirically derived stress intensity expressions are capable of predicting the crack growth behavior in both the length (on specimen surface) and depth (on the hole wall) directions.

Stress Intensity Factors of Slanted Through-Wall Cracks in Plate and Cylinder

2007 ◽  
Author(s):  
Nam-Su Huh ◽  
Do-Jun Shim ◽  
Ji-Ho Kim ◽  
Gery M. Wilkowski ◽  
Jun-Seok Yang
Keyword(s):  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Wall Thickness ◽  
Stress Intensity Factors ◽  
Crack Front ◽  
Internal Surface ◽  
Intensity Factors ◽  
Axial Tension

For Leak-Before-Break (LBB) analysis of nuclear piping, a circumferential through-wall crack (TWC) with the crack front parallel to the cylinder radius is typically postulated, i.e., an idealized TWC. Such assumption simplifies the LBB analysis significantly. However, in reality, an internal surface crack grows through the wall thickness and penetrates through the wall thickness at the deepest point. Hence, a TWC with different crack lengths at inner and outer surfaces is formed. Such a TWC is referred to as a “slanted TWC” in the present study. Leak rates as well as SCC and fatigue crack growth rates of slanted TWC are expected to be quite different from those of postulated idealized TWC. In this context, characterization of the actual TWC shape during crack growth due to fatigue or stress corrosion cracking is essential for accurate LBB analysis. Based on detailed 3-dimensional (3-D) elastic finite element (FE) analyses, the present paper provides stress intensity factors (SIFs) for plates and cylinders with slanted TWCs. As for loading conditions, axial tension was considered for the plates, whereas axial tension and global bending were considered for the cylinders. In order to cover the practical range of crack sizes, the geometric variables affecting the SIF were systematically varied. Based on FE analysis results, SIFs along the crack front, including the inner and outer surface points, were provided. The SIFs of slanted TWC can be used to evaluate the fatigue crack growth of a TWC and to perform detailed LBB analysis considering a more realistic crack shape.

Stress intensity factors for corner cracks at a hole under remote tension

1991 ◽  
Vol 7 (1) ◽  
pp. 76-81 ◽  
Author(s):  
Zhao Wei ◽  
Wu Xueren ◽  
Yan Minggao
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Intensity Factors ◽  
Corner Cracks
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