Computation of stress intensity factors for plate bending problem in fracture mechanics by hybrid mongrel finite element

1992 ◽  
Vol 42 (4) ◽  
pp. 581-589 ◽  
Author(s):  
C.H. Kang ◽  
G. de Saxcé
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Stress Intensity Factors ◽  
Plate Bending ◽  
Intensity Factors ◽  
Plate Bending Problem

Stress Intensity Factors for Complex-Cracked Pipes Based on Elastic Finite Element Analyses

2015 ◽  
Author(s):  
Jae-Uk Jeong ◽  
Jae-Boong Choi ◽  
Nam-Su Huh ◽  
Yun-Jae Kim
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Intensity Factors ◽  
Integrity Assessment ◽  
Complex Crack ◽  
Leak Before Break

A complex crack is one of severe crack that can occur at the dissimilar metal weld of nuclear piping. A relevant fracture mechanics assessment for a pipe with a complex crack has become interested in structural integrity of nuclear piping. A stress intensity factor is not only an important parameter in the linear elastic fracture mechanics to predict the stress state at the crack tip, but also one of variables to calculate the J-integral in the elastic plastic fracture mechanics. The accurate calculation of stress intensity factor is required for integrity assessment of nuclear piping system based on Leak-Before-Break concept. In the present paper, stress intensity factors of complex-cracked pipes were calculated by using detailed 3-dimensional finite element analysis. As loading conditions, global bending, axial tension and internal pressure were considered. Based on the present FE works, the values of shape factors for stress intensity factor of complex-cracked pipes are suggested according to a variables change of complex crack geometries and pipes size. Furthermore, the closed-form expressions based on correction factor are newly suggested as a function of geometric variables. These new solutions can be used to Leak-Before-Break evaluation for complex-cracked pipes in the step of elastic J calculation.

scholarly journals Fracture mechanics analysis of damaged turbine rotor discs using finite element method

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 107-112 ◽  
Author(s):  
Ivana Vasovic ◽  
Stevan Maksimovic ◽  
Dragi Stamenkovic ◽  
Slobodan Stupar ◽  
Mirko Maksimovic ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Crack Initiation ◽  
Stress Intensity Factors ◽  
Integral Approach ◽  
Intensity Factors ◽  
Principal Stresses ◽  
Element Method

This paper presents evaluation fracture mechanics parameters in low pressure turbine components. Critical locations such as keyway and dovetail area are experiencing stress concentration leading to crack initiation. Stress intensity factors were evaluated using the J-Integral approach available within ANSYS software code. The finite element method allowed the prediction of the point of crack initiation and the crack propagation using the orientations of the maximum principal stresses. Special attention in this investigation is focused to develop analytic expressions for stress intensity factors at critical location of low pres-sure steam turbine disc.

Fully Automated Mixed Mode Crack Propagation Analyses Using VCCM (Virtual Crack Closure-Integral Method) for Tetrahedral Finite Element

2011 ◽  
Vol 462-463 ◽  
pp. 900-905 ◽  
Author(s):  
Hiroshi Okada ◽  
Hiroshi Kawai ◽  
Takashi Tokuda ◽  
Yasuyoshi Fukui
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Crack Closure ◽  
Stress Intensity Factors ◽  
Integral Method ◽  
Large Scale ◽  
Intensity Factors ◽  
Element Analysis

The authors have been developing a crack propagation analysis system that can deal with arbitrary shaped cracks in three-dimensional solids. The system is consisting of mesh generation software, a large-scale finite element analysis program and a fracture mechanics module. To evaluate the stress intensity factors, a Virtual Crack Closure-Integral Method (VCCM) for the second-order tetrahedral finite element is adopted and is included in the fracture mechanics module. The rate and direction of crack propagation are predicted using appropriate formulae based on the stress intensity factors.

Study on Stress Intensity Factors for Circumferential Cracked Elliptical Pipes under Tension

2011 ◽  
Vol 299-300 ◽  
pp. 912-916
Author(s):  
W. Wang ◽  
Y. M. Cai ◽  
Y.J. Xie
Keyword(s):  
Finite Element Method ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Virtual Work ◽  
Principle Of Virtual Work ◽  
Intensity Factors

Stress intensity factor is one of the most important parameters in fracture mechanics. Based on the principle of virtual work and bending theory, this paper proposes a method to estimate the stress intensity factor for circumferential cracked elliptical pipes and derive the expression of the stress intensity factor for circumferential cracked elliptical pipes under tension. The compare of the result of this method and finite element method shows this method is credible and convenient.

Insulated Railroad Joint Design Evaluation by Coordinated Test and Finite Element Analysis

2013 ◽  
Author(s):  
Amir H. Iranmanesh ◽  
Robert L. West ◽  
Mehdi Ahmadian
Keyword(s):  
Finite Element ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Stress Intensity Factors ◽  
Experimental Tests ◽  
Parametric Modeling ◽  
Finite Element Models ◽  
Intensity Factors ◽  
Joint Design ◽  
Stress Analyses

The railroad industry faces challenges with bonded insulated joint designs in the present practice. A program initiated by Virginia Tech and the Transportation Technology Center Incorporated (TTCI) has been in progress to analyze and test a class of insulated joint designs featuring non-adhesive bolted connections. A hierarchical approach to finite element modeling with a parametric model maintaining essential mechanics of the joints has been applied to develop a bolted insulated joint design. The current paper reports on the recent phase of the program including development of experimental tests along with finite element analyses on scaled simplified insulated rail joint models. Two baseline rail joint configurations with simplified sections were considered for studying dominant mechanics under the AREMA (American Railway Engineering and Maintenance-of-Way Association) rail joint acceptance standard test loading and boundary conditions. The finite element models developed based on three-dimensional continuum elements incorporated bolt preloads and full-contact analysis. In the experimental tests, the strain analyses on 1/4 scaled polycarbonate rail joint specimens were performed by means of an array of strain gauge transducers mounted on the joint bars and a photoelasticity technique. The results of the experimental stress analyses were employed to validate the finite element models quantitatively and qualitatively in terms of load transfer mechanics and stress distribution. The validated models serve as baseline insulated joint configurations for developing fracture-mechanics-based fatigue-failure analysis. To investigate the role of cracks on the performance and reliability of joint bars, a damage tolerant analysis is performed on the rail joints utilizing linear elastic fracture mechanics. The locations of most critical type defects are estimated based on high stress/strain regions from stress analyses along with past experiences on failure of rail joints. To characterize the severity of theses defects under alternating loading conditions, stress intensity factors are computed as a function of crack length. Cracks of different lengths are introduced in the vicinity of the most fatigue-prone locations of the joint bar in a parametric modeling fashion. The fatigue-crack-growth-rate properties in terms of Paris Law scaling constants are selected from a survey of available material data. The number of loading cycles to failure is obtained by employing the computed stress-intensity factors as well as initial and final crack sizes. Predicted lifetimes as a function of pre-existing crack sizes and geometry of joint configuration can be used as a fracture-mechanics-based function for more accurate design of the rail joints.

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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