Computations of stress intensity factors for semi-elliptical cracks with high aspect ratios by using the tetrahedral finite element (fully automated parametric study)

2016 ◽  
Vol 158 ◽  
pp. 144-166 ◽  
Author(s):  
Hiroshi Okada ◽  
Hirohito Koya ◽  
Hiroshi Kawai ◽  
Yinsheng Li ◽  
Kazuya Osakabe
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Parametric Study ◽  
Intensity Factors ◽  
Aspect Ratios ◽  
Elliptical Cracks

Part-Elliptical Cracks Emanating From Open and Loaded Holes in Plates

1979 ◽  
Vol 101 (1) ◽  
pp. 12-17 ◽  
Author(s):  
T. E. Kullgren ◽  
F. W. Smith
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Opening ◽  
Plate Thickness ◽  
Hole Diameter ◽  
Elastic Analysis ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Elliptical Cracks

A linear elastic analysis using the finite element-alternating method is conducted for problems of single semi-elliptical and double quarter-elliptical cracks near fastener holes. Mode-one stress intensity factors are presented along the crack periphery for cases of open and loaded holes and crack opening displacements are calculated. Results are shown for a variety of crack geometries and loading conditions and for two ratios of hole diameter to plate thickness.

scholarly journals Fracture Mechanics and Beam Theory Analyses of Semi-Elliptical Cracks Originating in the Base of Rail

2012 ◽  
Author(s):  
David Y. Jeong ◽  
Michael E. Carolan ◽  
Hailing Yu ◽  
Benjamin Perlman ◽  
Jeffrey E. Gordon
Keyword(s):  
Stress Intensity ◽  
Fracture Mechanics ◽  
Stress Intensity Factors ◽  
Beam Theory ◽  
The United States ◽  
Intensity Factors ◽  
Northeast Region ◽  
Aspect Ratios ◽  
Serious Injuries ◽  
Elliptical Cracks

In May 2011, a derailment of a passenger train occurred in a tunnel in the northeast region of the United States. Fortunately, no serious injuries or fatalities resulted from this derailment. The probable cause of the derailment was determined to be a broken rail from a defect originating in the base of the rail. This internal rail base defect is characterized as having a crescent, thumbnail, or semi-elliptical shape. In addition, the formation and growth of this defect may have been exacerbated by corrosion. This paper describes engineering calculations to estimate the growth rate of this type of rail base defect. These engineering calculations are based on applying the principles of fracture mechanics and beam theory. Fracture mechanics principles are applied to determine stress intensity factors for the semi-elliptical shaped defect with different aspect ratios. Stress intensity factors are then used to estimate the growth of the defect under the accumulation of tonnage from repeated wheel passages. For this purpose, the rail is assumed to behave as a beam in bending.

Weight Functions and Stress Intensity Factors for Eccentric through Cracks in a 3-D Rectangular Plate Subjected to In-Plane Loading

2016 ◽  
Vol 853 ◽  
pp. 8-14
Author(s):  
Xu Teng Hu ◽  
Xu Jia ◽  
Ying Dong Song
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Rectangular Plate ◽  
Stress Intensity Factors ◽  
Interpolation Method ◽  
Unknown Coefficient ◽  
Weight Functions ◽  
Finite Element Models ◽  
Intensity Factors ◽  
Aspect Ratios

Three unknown coefficient weight functions for eccentric through cracks in a 3-D rectangular plate subjected to in-plane loading are proposed. 3-D finite element models of cracked rectangular plates within the whole range of crack aspect ratios, i.e., 0≤e/W≤0.8, 0.08≤a/(W-e)≤0.9, were established to obtain a reference SIF database for both crack points A and B, rather than 2-D finite element models. To improve the accuracy of the weight function, the coefficients were derived from this database using the Binary Lagrange Interpolation Method instead of Curve-Fitting Expression. Comparisons of stress intensity factors calculated using the present weight functions with finite element data for the high-order power law and residual stress distributions show high accuracy of the present weight functions.

Computations of Stress Intensity Factors for Deep Cracks in Plates by Using the Tetrahedral Finite Element

2012 ◽  
Author(s):  
Hiroshi Okada ◽  
Hirohito Koya ◽  
Hiroshi Kawai ◽  
Yinsheng Li
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Residual Stresses ◽  
Stress Intensity Factors ◽  
Structural Integrity ◽  
Intensity Factors ◽  
Welded Structures ◽  
Elliptical Cracks

In this paper, stress intensity factor solutions for deep half-elliptical cracks that are applicable to the structural integrity evaluations of welded structures are presented. Welded structures generally have some weld residual stresses resulting in stress corrosion crackings (SCCs). This paper describes a simple way to compute the stress intensity factors under the weld-residual stresses and the mode I stress intensity factor solutions for deep half-elliptical cracks. The residual stresses are set to vary proportional to the constant, the linear, the quadratic and the cubic functions of x which is the distance from the plate surface. Although we use a straightforward finite element method to perform the computations, we can quickly generate the stress intensity factor solutions as we make use of automatic mesh generation program for the tetrahedral finite element. Thus, it is very tractable to generate the finite element models with cracks. Furthermore, present solutions can be compared with those of Li et al. which are also presented in PVP 2012. We conclude that present method is useful for the evaluations of SIFs of cracks under the residual stresses.

A Coupled SBFEM-FEM Approach for Evaluating Stress Intensity Factors

2013 ◽  
Vol 353-356 ◽  
pp. 3369-3377 ◽  
Author(s):  
Ming Guang Shi ◽  
Chong Ming Song ◽  
Hong Zhong ◽  
Yan Jie Xu ◽  
Chu Han Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Complex Geometry ◽  
Stress Singularity ◽  
Intensity Factors ◽  
Finite Element Software ◽  
Scaled Boundary Finite Element ◽  
Element Method

A coupled method between the Scaled Boundary Finite Element Method (SBFEM) and Finite Element Method (FEM) for evaluating the Stress Intensity Factors (SIFs) is presented and achieved on the platform of the commercial finite element software ABAQUS by using Python as the programming language. Automatic transformation of the finite elements around a singular point to a scaled boundary finite element subdomain is realized. This method combines the high accuracy of the SBFEM in computing the SIFs with the ability to handle material nonlinearity as well as powerful mesh generation and post processing ability of commercial FEM software. The validity and accuracy of the method is verified by analysis of several benchmark problems. The coupled algorithm shows a good converging performance, and with minimum additional treatment can be able to handle more problems that cannot be solved by either SBFEM or FEM itself. For fracture problems, it proposes an efficient way to represent stress singularity for problems with complex geometry, loading condition or certain nonlinearity.

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