scholarly journals Stress intensity factors for multiple cracks in thick-walled cylinder

2015 ◽  
Vol 3 (2) ◽  
pp. 207
Author(s):  
Krunal G. Girase ◽  
Navneet K. Patil ◽  
Dinesh Shinde ◽  
Kanak Kalita
Keyword(s):  
Stress Intensity ◽  
Crack Size ◽  
Diameter Ratio ◽  
Multiple Cracks ◽  
Intensity Factors ◽  
Structural Geometry ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Walled Cylinder ◽  
Good Agreement

<p>The stress intensity factor (SIF) is the linear elastic fracture mechanics parameter that relates remote load, crack size and structural geometry. It predicts very accurately the stress state. In this work, cylinders with multiple cracks are considered. The following parameters are varied during the analysis of the cylinders: the number of cracks, (the variation in number of cracks ultimately led to a variation in the inter-crack spacing), the crack length to cylinder thickness ratio (a/t), the diameter ratio of the cylinders. Very good agreement between the finite element stresses and the theoretical stresses is seen.</p>

Boundary Element Formulations in Fracture Mechanics

1997 ◽  
Vol 50 (2) ◽  
pp. 83-96 ◽  
Author(s):  
M. H. Aliabadi
Keyword(s):  
Stress Intensity ◽  
Fracture Mechanics ◽  
Boundary Element ◽  
Growth Analysis ◽  
Review Article ◽  
Boundary Element Methods ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Transient Problems ◽  
Elastic Fracture

This article reviews advances in the application of boundary element methods (BEM) to fracture mechanics which have taken place over the last 25 years. Applications discussed include linear, nonlinear and transient problems. Also reviewed are contributions using the indirect boundary element formulations. Over this period the method has emerged as the most efficient technique for the evaluation of stress intensity factors (SIF) and crack growth analysis in the context of linear elastic fracture mechanics (LEFM). Much has also been achieved in the application to dynamic fracture mechanics. This review article contains 289 references.

scholarly journals Evaluation of the criticality of cracks in ice shelves using finite element simulations

2012 ◽  
Vol 6 (5) ◽  
pp. 973-984 ◽  
Author(s):  
C. Plate ◽  
R. Müller ◽  
A. Humbert ◽  
D. Gross
Keyword(s):  
Stress Intensity ◽  
Configurational Forces ◽  
Intensity Factors ◽  
Physical Processes ◽  
Ice Shelf ◽  
Critical Crack ◽  
Ice Shelves ◽  
Various Boundary Conditions ◽  
Linear Elastic ◽  
Elastic Fracture

Abstract. The ongoing disintegration of large ice shelf parts in Antarctica raise the need for a better understanding of the physical processes that trigger critical crack growth in ice shelves. Finite elements in combination with configurational forces facilitate the analysis of single surface fractures in ice under various boundary conditions and material parameters. The principles of linear elastic fracture mechanics are applied to show the strong influence of different depth dependent functions for the density and the Young's modulus on the stress intensity factor KI at the crack tip. Ice, for this purpose, is treated as an elastically compressible solid and the consequences of this choice in comparison to the predominant incompressible approaches are discussed. The computed stress intensity factors KI for dry and water filled cracks are compared to critical values KIc from measurements that can be found in literature.

A Criterion for Combination Rule in Flaw Assessment of Parallel Surface Cracks

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Masayuki Kamaya
Keyword(s):  
Stress Intensity ◽  
Structural Reliability ◽  
Crack Depth ◽  
Crack Size ◽  
Multiple Cracks ◽  
J Integral ◽  
Surface Cracks ◽  
Linear Elastic ◽  
Offset Distance ◽  
Bending Load

When multiple cracks approach one another, the stress intensity factor and J-integral value change due to the interaction of the stress field. Since the changes in these parameters are not always conservative in structural reliability evaluations, the interaction between multiple cracks should be taken into account. Section XI of the ASME Boiler and Pressure Vessel Code provides a flaw characterization rule for interacting multiple cracks. In Section XI, adjacent cracks are replaced with a coalesced single crack when the distance between the cracks is less than half of the crack depth. However, the criterion for the offset distance is given as an absolute value, although the magnitude of the interaction depends on the crack size. In the current study, an alternative criterion for the offset distance was examined. Linear-elastic and elastic–plastic analyses were performed for interacting semicircular and semi-elliptical surface cracks by the finite element method under a tensile or bending load. The change in the stress intensity factors and J-integral values due to the relative spacing of cracks was investigated. Based on the relationship between the magnitude of the interaction and the relative position of the cracks, the allowable ctriterion for the offset distance was discussed.

Propagation of Fatigue Cracks Emanating from Sharp Notches under Different Loading Direction

2007 ◽  
Vol 348-349 ◽  
pp. 461-464
Author(s):  
Matteo Benedetti ◽  
M. Beghini ◽  
L. Bertini ◽  
V. Fontanari
Keyword(s):  
Stress Intensity ◽  
Applied Load ◽  
Fatigue Cracks ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Notched Specimens ◽  
Loading Direction ◽  
Al 7075 ◽  
Elastic Fracture ◽  
Edge Cracks

The present paper is aimed at investigating the behaviour of fatigue cracks emanating from sharp V-shaped notches. To this purpose, several tests has been conducted on Al-7075-T651 notched specimens using a servohydraulic machine by changing the directions and levels of the applied load. The crack growth have been interpreted on the basis of a linear elastic fracture mechanics approach by adopting a weight function derived by the authors for the calculation of the stress intensity factors (SIFs) of inclined edge-cracks emanating from V-shaped notches.

Determination of Stress Intensity Factors for Partial Penetration Axial Cracks in Thin-Walled Cylinders

1986 ◽  
Vol 108 (2) ◽  
pp. 83-86 ◽  
Author(s):  
Weili Cheng ◽  
Iain Finnie
Keyword(s):  
Stress Intensity ◽  
Hoop Stress ◽  
Numerical Solutions ◽  
Stress Distributions ◽  
Intensity Factors ◽  
Axial Crack ◽  
Thin Walled ◽  
Walled Cylinder ◽  
Good Agreement

An approach based on the use of rotation and displacement solutions for a cracked element in plane strain is used to obtain the stress intensity factor for a long axial crack in a thin-walled cylinder. The hoop stress distribution in the cylinder prior to introduction of the crack is arbitrary. Results obtained with this approach are in good agreement with numerical solutions for several hoop stress distributions.

Examination of Ellipticity and Stress Intensity Factors by Photoelastic and Caustic Methods

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1898-1903
Author(s):  
Tsutomu Ezumi ◽  
Katsunao Suzuki
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Experimental Methods ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Freezing Method ◽  
Elastic Fracture ◽  
Caustics Method

In the field of linear elastic fracture mechanics, the stress intensity factor approach has been widely accepted as a valid means for predicting the behavior of a material in the presence of a crack or flaw. To optimize their dimension and to ensure their safety in service, a practical study of the strength under centrifugal force is important. In this paper, it is investigated that the stress intensity factors K_ and K_ on the rotating elliptic disks having outside cracks by means of combining the photoelastic freezing method and the caustics method. Stress intensity factors K and K were determined by using two experimental methods, as a function of ellipticity of the elliptic disk and at two different velocities. The results of these experimental methods was nearly agreement, and attracted the interest.

Evaluation of the SIF for the Multiple Crack Problems

2014 ◽  
Vol 638-640 ◽  
pp. 66-70
Author(s):  
Jun Yu Liu ◽  
Ping Zhang ◽  
Meng Han Liao ◽  
Bao Kuan Ning
Keyword(s):  
Stress Intensity ◽  
Orthotropic Material ◽  
High Accuracy ◽  
Mode I ◽  
Multiple Cracks ◽  
Intensity Factors ◽  
Multiple Crack ◽  
Crack Problems ◽  
Elastic Fracture ◽  
Scaled Boundary Finite Element

In elastic fracture mechanics the evaluation of the stress intensity factor (SIF) for multiple cracks problems is an important issue. In the paper the scaled boundary finite element method (SBFEM) is used to solve the SIF of mode I of multiple crack problems. The solving domain is partitioned into several sub-domains according to the number of cracks. Every sub-domain has its own scaling center. The characteristics of the SBFEM are preserved in every sub-domain. Numerical examples show that the SBFEM is effective with high accuracy in evaluating the multiple cracks fracture problems. It can be applied to treat the anisotropic materials conveniently. The stress intensity factors of unequal double-edged cracks in orthotropic material are provided.

The Influence of a Non-Aligned Semi-Elliptical Embedded Crack on the Stress Intensity Factor Distribution Along the Front of a Quarter-Circle Corner Crack in a Semi-Infinite Plate Under Pure Bending

2020 ◽  
Author(s):  
Cesar Levy ◽  
Qin Ma ◽  
Mordechai Perl
Keyword(s):  
Stress Intensity ◽  
Surface Crack ◽  
Infinite Plate ◽  
Crack Size ◽  
Engineering Practice ◽  
Multiple Cracks ◽  
Pure Bending ◽  
Corner Crack ◽  
Linear Elastic ◽  
Wide Range

Abstract Fitness-for-Service codes require whether non-aligned cracks be treated as coalesced or separate multiple cracks. The authors previously reported on the effect between an corner and an embedded parallel crack in 2-D and in 3-D scenarios subject to tensile loading. Since realistic crack configurations detected using non-destructive methods are generally 3-D in nature, the study of 3-D effect under different loading types is deemed necessary in order to obtain more practical guidance. In this study, we investigate stress intensity factors (SIFs) along the crack front of a quarter-circle corner crack when affected by a semi-elliptic surface crack in a semi-infinite large solid under pure bending. While keeping constant the geometry of the quarter-circle corner crack, the SIFs along its front are studied for a wide range of geometrical configurations of the surface crack by varying its ellipticity b1/a1 = 0.1∼1; the relative crack size of the two parallel cracks a1/a2 = 1/3∼2; the normalized vertical gap, H/a2 = 0.4∼2; and the normalized horizontal gap, S/a2 = −0.5∼2 between the two cracks on using linear elastic fracture mechanics (LEFM). The results from this study are collectively significant to the understanding of the correlation between the criteria and standards in Fitness-for-Service community and the consequence of their usage in engineering practice.

scholarly journals Two-Dimensional Stress Intensity Factor Analysis of Cracks in Anisotropic Bimaterial

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Chia-Huei Tu ◽  
Jia-Jyun Dong ◽  
Chao-Shi Chen ◽  
Chien-Chung Ke ◽  
Jyun-Yong Jhan ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Numerical Technique ◽  
Intensity Factors ◽  
Straight Crack ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Anisotropic Bimaterials

This paper presents a 2D numerical technique based on the boundary element method (BEM) for the analysis of linear elastic fracture mechanics (LEFM) problems on stress intensity factors (SIFs) involving anisotropic bimaterials. The most outstanding feature of this analysis is that it is a singledomain method, yet it is very accurate, efficient, and versatile (i.e., the material properties of the medium can be anisotropic as well as isotropic). A computer program using the BEM formula translation (FORTRAN 90) code was developed to effectively calculate the stress intensity factors (SIFs) in an anisotropic bi-material. This BEM program has been verified and showed good accuracy compared with the previous studies. Numerical examples of stress intensity factor calculation for a straight crack with various locations in both finite and infinite bimaterials are presented. It was found that very accurate results can be obtained using the proposed method, even with relatively simple discretization. The results of the numerical analysis also show that material anisotropy can greatly affect the stress intensity factor.

A LEFM Based Study on the Interaction Between an Edge and an Embedded Parallel Crack

2013 ◽  
Author(s):  
Q. Ma ◽  
C. Levy ◽  
M. Perl
Keyword(s):  
Stress Intensity ◽  
Separation Distance ◽  
Multiple Cracks ◽  
Service Needs ◽  
Parallel Crack ◽  
Linear Elastic ◽  
Parallel Cracks ◽  
Wide Range ◽  
Two Parallel Cracks ◽  
Elastic Fracture

Parallel cracks are often detected in components of various pressurized applications using non-destructive methods. For non-aligned parallel cracks, on-site service needs to decide whether they should be treated as coalesced or separate multiple cracks for Fitness-for-Service. Criteria and standards for the adjustment of multiple nonaligned cracks are very different from one another in existing resources. And those criteria and standards are often derived from on-site service experience without rigorous and systematic verification. Based on this observation, in this study the interaction between an edge and an embedded parallel crack is investigated to correlate criteria and standards from various resources in order to recommend the usage of those standards for the purpose of Fitness-for-service and to classify them as either conservative or non-conservative. If H and S represent the horizontal gap and vertical separation distance, respectively, between the cracks, and a2 is the length of the dominant crack, a parametric study of parallel crack separation distance and gap on the crack stress intensity factor has been undertaken. Stress intensity factors (SIFs) have been acquired for a wide range of the normalized gap of H/a2 = 0.4∼2 and the normalized separation distance of S/a2 = −0.5∼2 between the two parallel cracks based on the principle of linear elastic fracture mechanics (LEFM). This study indicates that certain existing standards/criteria provide results that are much more conservative than others while certain ones do not provide adequate information for application.

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