scholarly journals Stress Intensity Factors for Embedded, Surface, and Corner Cracks in Finite-Thickness Plates Subjected to Tensile Loading

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2807
Author(s):  
Jesús Toribio ◽  
Beatriz González ◽  
Juan-Carlos Matos ◽  
Óscar Mulas
Keyword(s):  
Stress Intensity ◽  
Crack Depth ◽  
Finite Thickness ◽  
Tensile Load ◽  
Corner Crack ◽  
Plate Length ◽  
Aspect Ratios ◽  
Favorable Configuration ◽  
Corner Cracks ◽  
Embedded Crack

The aim of this study is to obtain the stress intensity factor (SIF) along the crack front of elliptical cracks located in finite-thickness plates subjected to imposed displacement or applied tensile load, for different crack geometries (relative depths and aspect ratios) and crack configurations (embedded, surface, and corner). The SIF was calculated from the J-integral, obtained by the finite element method. The results show how the SIF grows with the increase in the relative crack depth and with the decrease in the aspect ratio, with the corner crack being the most dangerous configuration and the embedded crack the most favorable configuration. By increasing the plate length, the SIF rises when the plate is under imposed displacement and decreases when the plate is subjected to applied tensile load, both cases tending towards the same SIF curve.

Corner Crack at the Bore of a Rotating Disk

1976 ◽  
Vol 98 (4) ◽  
pp. 465-470 ◽  
Author(s):  
A. S. Kobayashi ◽  
N. Polvanich ◽  
A. F. Emery ◽  
W. J. Love
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Infinite Plate ◽  
Rotating Disk ◽  
Single Edge ◽  
Intensity Factors ◽  
Corner Crack ◽  
Aspect Ratios ◽  
Crack Problems ◽  
Corner Cracks

Stress intensity factors of corner cracks at the bore of a rotating disk are estimated from the stress intensity factor of a quarter-elliptical crack in a quarter infinite solid and pressurized by the hoop stress. Curvature effect of the bore is incorporated through a curvature correction factor derived from the stress intensity factors of a single edge-cracked bore in a large plate and a single edge-cracked semi-infinite plate. Stress intensity factors for quarter-elliptical cracks with crack aspect ratios of b/a = 0.2, 0.4, and 0.98 at crack depths of b/Ri = 0.1, 0.3 and 1.0 in a rotating disk with R0/Ri = 8 are determined. Application of the developed procedure to corner crack problems at a through-bolt hole is indicated.

A Procedure for Estimating the Stress Intensity Factor of a Flattened Surface Crack at a Nozzle Corner

1979 ◽  
Vol 101 (2) ◽  
pp. 181-183 ◽  
Author(s):  
A. S. Kobayashi ◽  
A. F. Emery ◽  
W. J. Love ◽  
A. Antipas
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Surface Crack ◽  
Finite Thickness ◽  
Normal Stresses ◽  
Intensity Factors ◽  
Qualitative Comparison ◽  
Crack Penetration ◽  
Corner Cracks ◽  
Crack Contour

A flattened surface crack at a nozzle corner is modeled by a segment of a semi-elliptical crack in a finite thickness plate with matching crack contour and crack pressure corresponding to the normal stresses in the uncracked nozzle corner. Lacking other solutions for comparison, a qualitative comparison was made between nondimensionalized stress intensity factors at the deepest crack penetration with those obtained experimentally for similar corner cracks in epoxy models.

Stress Intensity Factor Solutions for Narrow Plates

2014 ◽  
Vol 891-892 ◽  
pp. 784-790
Author(s):  
Matthew J. Hammond ◽  
Scott A. Fawaz
Keyword(s):  
Stress Intensity ◽  
Crack Depth ◽  
Three Dimensional ◽  
Sheet Thickness ◽  
Solution Space ◽  
Analytical Investigation ◽  
Crack Growth Behavior ◽  
Finite Width ◽  
Wide Range ◽  
Corner Cracks

Accurate quantification of crack tip stress intensity values is paramount in the analysis of damage tolerant structures. The present analytical investigation seeks to determine the stress intensity solutions for crack geometries outside the existing valid solution space and expand the analysts ability to capture representative crack growth behavior. The focus of this investigation is to calculate the stress intensity factors of single quarter-elliptical corner cracks emanating from centrally located holes in finite width plates under various loading conditions (remote tension, bending, and pin loading). Many of the available finite width corrections are singled valued and universally applied to all locations along the crack front. Early investigations into the validity of this application indicated that this correction procedure produces stress intensity values +/- 30% from new solutions. The crack depth to length ratio and depth to thickness ratio can also significantly influence the accuracy of historical finite width solutions and corrections. The analytical investigation utilizes the three dimensional virtual crack closure technique and well-structured, completely hexahedral, element meshes. Stress intensity values are generated for a wide range of ratios for crack depth to crack length, crack depth to sheet thickness, hole radius to sheet thickness, and sheet width to hole diameter. This effort is being executed under a US DoD Technical Corrosion Collaboration program.

Inner and Outer Cracks in Internally Pressurized Cylinders

1977 ◽  
Vol 99 (1) ◽  
pp. 83-89 ◽  
Author(s):  
A. S. Kobayashi ◽  
N. Polvanich ◽  
A. F. Emery ◽  
W. J. Love
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Finite Thickness ◽  
Internal Surface ◽  
Surface Cracks ◽  
Single Edge ◽  
Intensity Factors ◽  
Curvature Effects ◽  
Aspect Ratios ◽  
Dimensional Finite Element

Stress intensity factors of pressurized surface cracks at the internal surface and un-pressurized surface cracks at the external surface of an internally pressurized cylinder are estimated from stress intensity factors of a semi-elliptical crack in a finite-thickness flat plate. Curvature effects of the cylinder are determined by comparing two-dimensional finite element solutions of fixed-grip, single edge-notched plates and single edge-notched cylinders. Stress intensity factors for semi-elliptical cracks with crack aspect ratios of b/a = 0.2 and 0.98 at crack depths up to 80 percent of the cylindrical wall thickness are shown for internally pressurized cylinders with outer to inner diameter ratios, Ro/Ri, ranging from 10:9 to 5:4 for outer surface cracks and to 3:2 for inner surface cracks.

Development of Stress Intensity Factors for Cracks With Large Aspect Ratios in Pipes and Plates

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Yinsheng Li ◽  
Kunio Hasegawa ◽  
Makoto Udagawa
Keyword(s):  
Stress Intensity ◽  
Wall Thickness ◽  
Stress Intensity Factors ◽  
Crack Depth ◽  
Influence Coefficient ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Element Analysis ◽  
Aspect Ratios ◽  
Pipe Radius

The stress intensity factors (SIFs) for pipes containing semi-elliptical surface cracks with large aspect ratios were calculated by finite-element analysis (FEA). The cracks were circumferential and axial surface cracks inside the pipes. The parameters of the SIFs are crack aspect ratio, crack depth, and the ratio of pipe radius to wall thickness. In comparing SIFs for plates and pipes, it can be clarified that SIFs for both plates and thin pipes with t/Ri ≤ 1/10 are almost the same, and the SIFs for plates can be used as a substitute for pipes with t/Ri ≤ 1/10, where t is the pipe wall thickness, and Ri is the inner radius of the pipe. This means that it is not necessary to provide SIF solutions for pipes with t/Ri ≤ 1/10, and it is suggested that the number of tables for influence coefficient values for pipes can be significantly reduced.

Elliptical Crack in a Finite-Thickness Plate Subjected to Tensile and Bending Loading

1974 ◽  
Vol 96 (1) ◽  
pp. 47-54 ◽  
Author(s):  
R. C. Shah ◽  
A. S. Kobayashi
Keyword(s):  
Free Surface ◽  
Stress Intensity ◽  
Finite Thickness ◽  
Elliptical Crack ◽  
Aspect Ratios ◽  
Analytical Results ◽  
Magnification Factors ◽  
Bending Loading ◽  
Resultant Stress

Stress intensity magnification factors for an elliptical crack embedded in a finite thickness plate subjected to tensile and bending loading are estimated by judicious use of analytical results obtained previously. These analytical results involve the stress intensity magnification factors for an embedded elliptical crack approaching the free surface of a semi-infinite solid and pressurized by a constant or by a linearly varying pressure. The resultant stress intensity magnification factors for the elliptical crack in a plate are presented in graphical forms for various crack aspect ratios, eccentricity, and proximity factors.

Effect of Helix Angle on the Stress Intensity Factor of a Cracked Threaded Bolt

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
S. Suresh Kumar ◽  
Raghu V. Prakash
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Depth ◽  
Helix Angle ◽  
Mode Ii ◽  
Mode Iii ◽  
Aspect Ratios ◽  
Depth Ratio ◽  
Crack Depth Ratio

The fracture behavior of a crack in a threaded bolt depends on the stress intensity factor (SIF). Available SIF solutions have approximated the threaded bolt as a circular groove, thus, the SIF predominantly corresponds to the opening mode, mode-I. As a thread in a bolt has a helix angle, the crack propagates under mixed mode conditions (opening, sliding and tearing), esp. when the crack sizes are small. This paper presents the results of SIF solutions for a part-through crack emanating from a Metric threaded bolt. A 3D finite element model with preexisting flaws was generated to calculate the SIF values along the crack front. Crack aspect ratios in the range of (0.2 < (a/c) < 1) and crack depth ratios in the range of (0.1 < (a/d) < 0.5) (where “a” is crack length, “c” is semi major axis of ellipse and “d” is minor diameter of the bolt) were considered along the crack plane for the SIF estimation. The SIF values at the midregion decreases with an increase in aspect ratio (a/c), and SIF increases when the crack depth ratio (a/d) increases in the midregion. Close to the free edges, higher SIF values was observed for crack depth and aspect ratios ranging between 0.2 and 0.6 compared to midregion. In the crack surface region, up to a crack depth ratio of 0.25, significant influence of mode-II and mode-III fracture was noted for shallow cracks (a/c < 0.2). Significant influence of mode-II and mode-III fracture was observed for semicircular cracks (a/c = 1) beyond the crack depth ratio of 0.3.

Stress Intensity Factors for Unusual Semi-Elliptical Surface Cracks With Ratio a/l Greater Than 0.5

2009 ◽  
Author(s):  
Christian Malekian ◽  
Eric Wyart ◽  
Michael Savelsberg ◽  
David Lacroix ◽  
Anne Teughels ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Finite Elements ◽  
Aspect Ratio ◽  
Intensity Factor ◽  
Crack Depth ◽  
Surface Cracks ◽  
Extended Finite Element ◽  
Aspect Ratios ◽  
Theoretical Limitation

Most of the literature about fracture mechanics treats cracks with a flaw aspect ratio a/l lower or equal to 0.5 where a is the crack depth and l the total length of the crack. The limitation to 0.5 corresponds to a semi-circular shape for surface cracks and to circular cracks for subsurface cracks. This limitation does not seem to be inspired by a theoretical limitation nor by a computational limit. Moreover, limiting the aspect ratio a/l to 0.5 may generate some unnecessary conservatism in flaw analysis. The present article deals with surface cracks in plates with more unusual aspect ratios a/l&gt;0.5 (narrow cracks). A series of Finite-Elements calculations is made to compute the stress intensity factor KI for a large range of crack depths having an aspect ratio greater than 0.5. The KI values can be used with the same formalism as the ASME XI Appendix A, such that this approach can provide an extension above the inherent limitation to 0.5. Some of the results obtained are checked by using two different Finite-Elements softwares (Systus and Ansys), each one with a different cracked mesh. In addition, a comparison is made for some cases with results obtained by a XFEM approach (eXtended Finite-Element Method), where the crack does not need to be meshed in the same way as in classical Finite-Elements. The results show a reduction of stress intensity factor, sometimes significant, when considering a flaw aspect ratio above 0.5 instead of the conventional semi-circular flaw. They also show that it is not always possible to reduce the analysis of KI to only 2 points, namely the crack surface point and the crack deepest point. The growth by fatigue or by corrosion of a crack with such unusual shape should still be investigated.

Stress intensity factors for semi-elliptical surface cracks in semicircularly notched tension plates

1997 ◽  
Vol 32 (3) ◽  
pp. 229-236 ◽  
Author(s):  
X B Lin ◽  
R A Smith
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Depth ◽  
Finite Thickness ◽  
J Integral ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Wide Range ◽  
Half Length ◽  
Half Thickness

Stress intensity factors for semi-elliptical surface cracks located at the centre of a semicircular edge notch in a finite thickness plate subjected to a remote tensile load are presented in a tabulated format. A wide range of geometry ratios are considered. They are all combinations of the following ratios: the ratio of crack surface half-length to plate half-thickness, c/t = 0.2, 0.4, 0.6, 0.8 and 0.95; the ratio of crack depth to surface half-length, a/c = 0.2, 0.4, 0.6, 0.8 and 1; and the ratio of notch radius to plate half-thickness, r/t = 0.5, 1, 2 and 3. Both the quarter-point displacement and J.-integral methods based on three-dimensional finite element analyses were employed for the calculation of stress intensity factors. The calculation accuracy was studied by analysing the J.-integral path independence and comparing stress intensity factor results with other solutions available in the literature.

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