Experimental Determination of Stress Intensity Factor Distributions in Engineering Problems

1993 ◽  
Vol 46 (11S) ◽  
pp. S29-S40 ◽  
Author(s):  
C. W. Smith
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Intensity Factors ◽  
Local Modes ◽  
Engineering Problems ◽  
Practical Engineering ◽  
Stress Optic Law

Following a brief introduction of the concept of stress intensity factor from fracture mechanics and the frozen stress method from photoelasticity, an algorithm is developed from fracture mechanics equations and the stress-optic law for converting stress fringe measurements into a form useful for determining the stress intensity factor. This algorithm covers all three local modes of deformation and is used to analyse frozen stress slices along the border of cracks to obtain distributions for stress intensity factors K1, K2 and K3. The use of the method is illustrated by three examples from practical engineering problems and results are compared with the literature where possible.

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 The Application of Fracture Mechanics to the Problem of Crevasse Penetration

1976 ◽  
Vol 17 (76) ◽  
pp. 223-228 ◽  
Author(s):  
R. A. Smith
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Close Agreement ◽  
Elastic Stress ◽  
Intensity Factors ◽  
Wide Range ◽  
Sharp Crack

AbstractThe elastic stress intensity factor is a parameter used in fracture mechanics to describe stress conditions in the vicinity of the tip of a sharp crack. By superimposing solutions of stress intensity factors for different loading conditions, equations are derived which model crevasses in ice. Solutions are presented for the theoretical depth of isolated crevasses, free from or partially filled with water. Close agreement exists with a previous calculation by Weertman using a different technique. The effect of crevasse spacing is investigated and it is demonstrated that closer spacing always reduces crevasse depth, but over a wide range of spacing the predicted variation in depth is slight.

scholarly journals The Application of Fracture Mechanics to the Problem of Crevasse Penetration

1976 ◽  
Vol 17 (76) ◽  
pp. 223-228 ◽  
Author(s):  
R. A. Smith
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Close Agreement ◽  
Elastic Stress ◽  
Intensity Factors ◽  
Wide Range ◽  
Sharp Crack

Abstract The elastic stress intensity factor is a parameter used in fracture mechanics to describe stress conditions in the vicinity of the tip of a sharp crack. By superimposing solutions of stress intensity factors for different loading conditions, equations are derived which model crevasses in ice. Solutions are presented for the theoretical depth of isolated crevasses, free from or partially filled with water. Close agreement exists with a previous calculation by Weertman using a different technique. The effect of crevasse spacing is investigated and it is demonstrated that closer spacing always reduces crevasse depth, but over a wide range of spacing the predicted variation in depth is slight.

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.

Fracture Mechanics Analysis of the Dynamic Stress Intensity Factor of 3-Point Bending Specimen Suffering Cyclic Loads

2011 ◽  
Vol 143-144 ◽  
pp. 503-507 ◽  
Author(s):  
Ya Yu Huang ◽  
Xiang Ping Hu ◽  
Tao Hong Liao
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Dynamic Stress ◽  
Dynamic Stress Intensity Factor ◽  
Cyclic Loads ◽  
Fracture Characteristics ◽  
Mechanics Analysis ◽  
Practical Engineering

Fracture mechanics analysis of the Dynamic Stress Intensity Factor of a pre-cracked 3-Point Bending Specimen suffering cyclic loads has been studied. Using the theoretical equivalent system of the pre-cracked 3-Point Bending Specimen, the Dynamic Stress Intensity Factor could be obtained theoretically. The finite element method was then applied to study the dynamic behaviors of the Dynamic Stress Intensity Factor under different cyclic loads' conditions using the standard software ABAQUS. The results have also been analyzed and discussed, which provided a deeper view for the fracture characteristics of the materials and could be used to guide further researches and practical engineering design.

Determination of Residual Stresses From Stress Intensity Factor Measurements

1971 ◽  
Vol 93 (2) ◽  
pp. 242-246 ◽  
Author(s):  
S. Vaidyanathan ◽  
I. Finnie
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Electron Beam ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Measurement ◽  
Residual Stress Distribution ◽  
Intensity Factors ◽  
State Of Stress

It is shown that a familiar procedure for obtaining stress intensity factors for a plate containing a through crack may be inverted. That is, stress intensity factor measurements may be used to deduce the state of stress that existed in the plate prior to introduction of the crack. This approach to residual stress measurement appears to be superior to existing methods for situations in which the stress gradients in the plane of the plate are large. As an illustration, the residual stress distribution in an electron beam welded aluminum plate is determined.

scholarly journals Determination of Stress Intensity Factors in Low Pressure Turbine Rotor Discs

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Ivana Vasovic ◽  
Stevan Maksimovic ◽  
Katarina Maksimovic ◽  
Slobodan Stupar ◽  
Gordana Bakic ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Finite Elements ◽  
Intensity Factor ◽  
Turbine Rotor ◽  
Analytic Formula ◽  
Intensity Factors ◽  
Lp Turbine ◽  
Critical Locations

An attention in this paper is focused on the stress analysis and the determination of fracture mechanics parameters in low pressure (LP) turbine rotor discs and on developing analytic expressions for stress intensity factors at the critical location of LP steam turbine disc. Critical locations such as keyway and dovetail area experienced stress concentration leading to crack initiation. Major concerns for the power industry are determining the critical locations with one side and fracture mechanics parameters with the other side. For determination of the critical locations in LP turbine rotor disc conventional finite elements are used here. For this initial crack length and during crack growth it is necessary to determine SIFs. In fatigue crack growth process it is necessary to have analytic formulas for the stress intensity factor. To determine analytic formula for stress intensity factor (SIF) of cracked turbine rotor disc special singular finite elements are used. Using discrete values of SIFs which correspond to various crack lengths analytic formula of SIF in polynomial forms is derived here. For determination of SIF in this paper, combinedJ-integral approach and singular finite elements are used. The interaction of mechanical and thermal effects was correlated in terms of the fracture toughness.

scholarly journals A Numerical Approach for the Determination of Mode I Stress Intensity Factors in PMMA Materials

2014 ◽  
Vol 4 (3) ◽  
pp. 644-648
Author(s):  
F. Khelil ◽  
M. Belhouari ◽  
N. Benseddiq ◽  
A. Talha
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Numerical Approach ◽  
Experimental Results ◽  
Intensity Factors ◽  
Element Analysis ◽  
Experimental Values

An evaluation technique of the KI stress intensity factors (SIF) by a numerical investigation using line strain method is presented in this paper. The main purpose of this research is to re-analyze experimental results of fracture loads from polymethyl-metacrylate (PMMA) specimens (fully finite plates). Stress intensity factor equation calculation is derived from the Williams stress asymptotic expansion. Possible error caused by strain gradients across the gage length is minimized by integrating the equation in the KI  calculation. Theoretical and computed values using finite element analysis of stress intensity factors are compared with experimental results. A good agreement is observed between the present approach and experimental values. It is shown that, in the case of a through-plate crack, the stress intensity factor can be calculated with adequate accuracy using the proposed method.

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