The stress intensity factor solution given by isida et al. The purpose of this paper is to present stress intensity factors for a wide range of nearly semielliptical surface cracks in pipes and rods. Stress intensity factor estimated by using an appropriate modeling of components is essential for evaluation of crack growth behavior in stress corrosion cracking. Approximate solutions at the deepest point for arbitrary crack face loading. The stress intensity factor, is used in fracture mechanics to predict the stress state stress intensity near the tip of a crack or notch caused by a remote load or residual stresses. Stressintensity factors for internal and external surface. Stress intensity factor for an elliptical crack approaching. These cracks then grow into semi elliptical shapes while extending into the shaft.
Deepdyve is the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Longitudinal butt welded joints are critical regions as they are loaded transversely. The elastic and plastic stress intensity factors used for the representation of the experimental results are computed by using fullsize 3d finite element analysis of the imitation models with surface. The surface cracks were oriented on a plane normal to the axis of pipes or rods. However, it is difficult to evaluate the intensity of the interaction quantitatively because there are many factors, such as the relative position, size, and geometry of the cracks. The crack initiation life is highly dependent on the k tvalue. Stress intensity factors of a semielliptical crack in a hollow cylinder. Stress intensity factors for surface semi elliptical crack in cylindrical specimen under combined torsion and axial compression p. Weight functions and stress intensity factors for internal surface semielliptical crack in thickwalled cylinder. The configuration of standard semielliptical surface cracks is described using the outer surface crack lengths and the crack depths. Stress intensity factor calculations for semielliptical surface cracks in round bars subjected to bending and torsion using a threedimensional finite element model are presented. Effects of different parameters such as railwheel friction, crack surface friction, trapped liquid and crack length growth were also studied in. Guidelines for the analysis and design of damage tolerant aircraft structures, 2002. Stress intensity factors for a semielliptical surface.
A uniform stress and a linear stress distribution were used as the two references to determine the weight functions. In this investigation, the weight function method was employed to calculate stress intensity factors for semielliptical surface crack in a hollow cylinder. Stress intensity factors for surface semielliptical crack in. Analysis of stress intensity factor along semielliptical surface crack reinforced by composite patching. The generalpurpose finite element code abaqus is used in this study to obtain the stress fields of the hoopwrapped composite cylinder and the stress intensity factor along the semielliptical crack front. Stress intensity factors for semielliptical surface cracks ac 0. For plates with semi elliptical surface crack, newman, raju and kou have reported the stress intensity factor. The crack initiation period is followed by the fatigue crack growth period, recall figure 2. The common topic of the studies is the investigation on the effect of the vessels radius to thickness ratio t c r c and the effect of crack geometry ratio ac on the stress intensity factor.
A thesis submitted in partial fulfillment of the requirements for the degree of. As a result of the symmetry, only oneeighth of the cylinder is considered in the modeling. Most practical crack configurations are embedded and surface breaking planar cracks subjected to com plex twodimensional stress fields. Stress intensity factors are calculated for the geometry shown in fig. Welded joints are prone to fatigue cracking with the existence of welding defects and bending stress. The formula can be divided into the following two parts. The stress intensity factor sif for semi elliptical surface cracks subjected to mode i and mode iii loading was found by using a three dimensional finite element method. Introduction three dimensional cracks such as a surface or. Then, the t stress weight functions for the deepest.
The configurations were subjected to either remote. Effect of welding residual stress on stress intensity factors for semielliptical surface cracks in a buttwelded steel plate. Stress intensity factors for semi elliptical surface cracks in platetoplate butt welds with parallel misalignment of same thickness author links open overlay panel h. Further, a number of methods are now available for evaluating stress intensity factors2 to 8 and limit loads9 to 15 of structures containing flaws. Stress intensity factors for axial semielliptical surface cracks and embedded elliptical cracks at longitudinal butt welded joints of steellined pressure tunnels and shafts considering weld shape. Effect of welding residual stress on stress intensity. Stress intensity factor of semielliptical surface crack in a cylinder. Threedimensional stress intensity factor analysis of a. From this work, it is evident that the magnitude of the interaction between two cracks depends strongly on the distance between them and quickly becomes insigni. Stressintensity factors for semielliptical surface cracks under.
However, for plates with partly throughwall cracks, namely an semi elliptical crack with an imaginary crack depth a which is greater than the thickness t of the plate, the stress intensity factor was not reported. Rapid method of stress intensity factor calculation for semi. Stress intensity factor, approximate method, semi elliptical cracks, multiple site damage 1. The weight function method is used to calculate stress intensity factors for a semielliptical surface crack in a plate exposed to stress gradients. The values obtained are normalized according to the sif value of a surface crack contained in an infinite plate, i. Pdf stress intensity factors for circumferential surface. In recent years an effective method called the weight or influence function method has been developed to analyze the stress intensity factor, k, for surface cracks subjected to arbitrarily distributed surface stresses15. Stress intensity factor of semielliptical surface crack. Stressintensity factors for semielliptical surface. Stress intensity factors for mixedmode crack growth in.
Stress intensity factors for a semielliptical surface crack in a tshaped geometry. Burdekinstress intensity factors for a wide range of longdeep semielliptical surface cracks, partly throughwall cracks and fully throughwall cracks in tubular members eng fract mech, 73 2 2006, pp. Stress intensity factors for semielliptical surface cracks. Mixed mode conditions along the crack edge are characterized. When for steel liners of pressure tunnels and shafts highstrength steels are used, welded joints are subject to the risk of hydrogen induced cold cracking in the base material. Stress intensity interaction between dissimilar semielliptical surface cracks article pdf available in international journal of pressure vessels and piping 146 july 2016 with 191 reads. Stress intensity factors for semielliptical surface. J shain anal 39245260 2011 mode iii stress intensity factor of surface crack in 23. This revised cefm accurately predicted the dependence of crack growth rates on the stress intensity factor and offers an.
The problem of a beam containing a semielliptical surface crack and subjected to tension or bending loading is investigated. The effect of corrosion patch geometry on stress intensity. Analysis of stress intensity factor along semielliptical. Analysis of stress intensity factors for surface cracks. Materials 2017, 10, 166 3 of 19 determination of the sif under bending stress. Stress field induced by body force doublet in a semi infinite body is used as a fundamental solution. Two different stress ratio values are applied several times to each imitation model in order to fix the experimental crack front positions. With these influence coefficients, the stress intensity factor can be calculated for a wide range of surface crack geometries. In this paper a singular integral equation method is applied to calculate the stress intensity factor along crack front of a 3d surface crack. Stress intensity factors for a semielliptical surface crack. Starting from a reference load and stress intensity factor an approximate reference displacement field is calculated analytically. In the second part, weight functions with five and six terms are derived separately at the surface and the deepest points of semi elliptical crack to determine the stress intensity factors. Choose singularity options wisely for elastoplastic conditions. For the appropriate modeling of welded components with a surface crack, it is important to understand the effects of residual stress distribution and the geometry of component on the.
The geometry factor, y, accounts for the effect of geometry of the crack and the body, the boundary conditions and the type of loading. Semielliptical surface crack an overview sciencedirect topics. The effect of the weld toes in welded joints is considered using a weld toe magnification factor m k, and the scf equations are taken into account for misalignment. Stress concentrations around notches were considered in chapter 3 with the stress concentration factor k t as an important parameter for characterizing the severity of the stress distribution around the notch. Stressintensity factors for semielliptical surface cracks.
Semielliptical surface cracks are one of the most frequent cracks found in many structures in service, such as offshore structures and aircraft components. Then the problem is formulated as an integral equation with a singularity of the form of r 3. Kim yj, shim dj, choi jb, kim yj 2002 approximate j round. Stress intensity factor of semielliptical surface crack in. Stress intensity factor for an embedded elliptical crack approaching the free surface of a semi infinite solid and subjected to a linearly varying pressure is presented in a nondimensional form as a function of position around the crack periphery, crack aspect ratio, and crack distance from the free surface. Stress intensity factors of semielliptical surface cracks. Stress intensity factors for tangential surface cracks in. Kassir and sih 26 obtained the solution of the stress intensity factor for an elliptical crack in an infinite body under a remote uniform shear stress. In these equations, the newman and raju equation 15 for a semielliptical surface crack in a plain plate is chosen as the base stress intensity equation. It is a theoretical construct usually applied to a homogeneous, linear elastic material and is useful for providing a failure criterion for brittle materials, and is a critical technique in the discipline of.
An empirical stressintensity factor equation for the surface. The paper concludes with a parametric study that provides a set of stress intensity factors for semielliptical surface. Stress intensity factor, approximate method, semielliptical cracks, multiple site damage 1. The configurations were subjected to either remote tension or bending loads. Finite element investigation of stress intensity factors of. Stress intensity factor for a semielliptical crack. Evaluation of scc growth under residual stress field report 2. Stress intensity factors for a wide range of nearly semielliptical surface cracks in pipes and rods are presented.
Stress intensity factors for an elliptical crack approaching the surface of a semielliptical solid. Stress intensity factors for semielliptical surface cracks in platetoplate butt welds with parallel misalignment of same thickness. Keywords crack length,fatigue crack growth, pressure vessel, stress intensity factor, semielliptical crack. Pdf stress intensity factor for a semielliptical crack subjected to. The only exact analytical weight function for a planar crack was obtained for a circular one. Consider a cylinder with a finite elliptical axial surface crack, subject to the. The weight function method was applied and appropriate weight functions have been derived using the petroskiachenbach crack opening displacement expression. Weight functions for tstress for semielliptical surface. Absolute values of stress intensity factor agree well for semicircular and shallow semi elliptical cracks, but values were below those of the reference case for deep, narrow semi elliptical cracks.
For an accurate engineering fatigue and fracture assessment, solutions for stress intensity factors sif are required, considering. The weight function represents the sif induced by a unit concentrated load. Pdf stress intensity interaction between dissimilar semi. Improved formula for the stress intensity factor of. In this paper, we use the weight function for an elliptical crack embedded in an infinite elastic media in conjunction with the alternating method to derive the exact analytical solution for the stress intensity factor for a semielliptical surface crack subjected to an arbitrary mode i loading. Normalized modei stress intensity factors sifs are presented for a wide practical range of tangential surface cracks contained in rotating hollow disks.
Stress intensity factors for elliptical and semielliptical cracks. The most effective method of evaluating the stress intensity factor induced by an applied stress field is by using the weight function for a given cracked body. In order to check the accuracy of the present results. Stress intensity factors for axial semielliptical surface. The stress intensity factor distributions along the crack front for various surface cracks. Stress intensity factor influence coefficients for a wide range of semielliptical surface cracks on the inside or outside of a cylinder are presented. Calculation of sifs for semielliptical surface cracks in. How can i calculate the stress intensity factor of semi.
In this study, in order to investigate the intensity of interaction, the stress intensity factor sif of interacting semi elliptical surface cracks was evaluated by the finite element method and. Stress intensity factor of a wide range of semielliptical. Then you can assign the semi elliptical part of the geometry crack properties, i. Stress intensity factor for a semielliptical crack subjected to an. Governing parameters are aspect ratio, depth and radial coordinate of the crack and ratios of disk radii and thickness. However, due to the complexities of the nature of the surface crack problem, closed form solutions are not possible, and a numerical or an experimental approach must be used to determine the stress intensity factors for surface cracks. Stress intensity factors for semielliptical surface cracks in a plate. This paper presents the application of the weight function method for the calculation of elastic t stress for semielliptical surface cracks. For example, the stress intensity factor associated with a semielliptical surface crack in a pipe submitted to internal pressure is given by. Figures 11 and 12 shows stress intensity factors obtained by several investigators for a semielliptical surface crack in a finitethickness plate. The interaction between multiple surface cracks is an important consideration in the cracking behavior due to thermal fatigue and stress corrosion cracking. The derived weight functions account for both the global weldment geometry and the weld profile characterised by the weld angle.
The stress intensity factor for the circumferential semielliptical surface cracks in a hollow cylinders cross section under torsion is calculated using a finiteelement technique. Stress intensity interaction between dissimilar semi. Stress intensity factor of semielliptical surface crack in internally. Further, a number of methods are now available for evaluating stress intensity factors 2 to 8 and limit loads9 to 15 of structures containing flaws. Stress intensity factor of the hoopwrapped cylinder. Determining stress intensity factor means in essence the derivation of the function. Deepdyve is the easiest way to get instant access to the academic journals you need. The relative difference for shorter cracks depths was between 2 to 5% if compared to the literature value. Furthermore, the influence of the interaction differs with the crack tip position along the front. Stress intensity factors for elliptical cracks dtic.
Proceedings of the asme 2018 37th international conference on ocean, offshore and arctic engineering. Figure 11 shows the results for a surface stress intensity factors of semielliptical surface cracks in finitethickness plates 825 2,0 1. Weight function and stress intensity factor for a semielliptical surface saddle crack in a tubular welded joint. This is also case in the asme xi appendix a where stress intensity factors k i formulations are given for a large range of crack depths and for a flaw aspect ratio al between 0 and 0. The key challenge of such predictions using fracture mechanics is how to accurately calculate the stress intensity factor sif. A method for calculating stress intensity factors for edge and surface cracks in weldments has been presented. It is a theoretical construct usually applied to a homogeneous, linear elastic material and is useful for providing a failure criterion for brittle materials. Approximate determination of stress intensity factor for.
Stress intensity factor distributions at the edge of semi circular and semi elliptical surface cracks are obtained for cracks aligned perpendicular to the surface of a semi infinite solid subject to remote shear parallel to the plane of the crack. Semielliptical surface crack an overview sciencedirect. Fracture mechanics is a useful approach in which the fatigue life of the welded joint can be predicted. Stress intensity factors for axial semi elliptical surface cracks and embedded elliptical cracks at longitudinal butt welded joints of steellined pressure tunnels and shafts considering weld shape. The paper concludes with a parametric study that provides a set of stressintensity factors for semielliptical surface.
Improved formula for the stress intensity factor of semi elliptical surface cracks in welded joints under bending stress yang peng 1, chao wu 2, yifu zheng 1,3 and jun dong 1, 1 college of civil engineering, nanjing tech university, nanjing 211816, china. The present method allows to calculate stress intensity factors with minimal numerical effort at the deepest point. Stress intensity factors for circumferential surface. Stress intensity factors for elliptical and semielliptical. Stress intensity factor for cracks emanating from a shaft. Variation of stress intensity factor and crack opening. Stress intensity factors for axial semielliptical surface cracks and embedded elliptical cracks at longitudinal butt welded joints of steellined pressure tunnels and shafts considering weld shape author links open overlay panel a. Fatigue crack growth prediction of a semielliptical. Stressintensity factors for surface cracks in functionally. Paper open access stress intensity factor for a semi. Kim yj, shim dj, choi jb, kim yj 2002 approximate j round bars.
First, the weight function method for the calculation of t stress previously developed for twodimensional crack problems was extended for the t stress calculation for threedimensional crack problems. Stressintensity factors for an internal semielliptical. Calibration of the model to overcome this underprediction is discussed. Influence of the interaction on stress intensity factor of. The paper presents numerical estimation of stress intensity factor sif of such cracks in circular solid shaft when subjected to bending and twisting loads in elastic conditions.
Therefore, an evaluation based on the threshold stress intensity factor range. Improved formula for the stress intensity factor of semi. The configuration of the semiellipse follows the equation b 2 s. Fatigue cracks nucleate at the surface of the shaft operating under cyclic load. Pdf stress intensity factors for internal surface cracks. Introduction many investigations have shown that sudden failures of. Afrlvawptr20033002, usaf damage tolerant design handbook. Eight semielliptical surface cracks are considered with a constant ratio bs, whereas the angle. In this study, in order to investigate the intensity of interaction, the stress intensity factor sif of interacting semi elliptical surface cracks was evaluated by the finite element method and finite element alternating method. For a pressurized cylinder with hoop wrapped composite layer, its stress intensity factor k may be expressed as 1 k p i r i t. Stress intensity factors for an elliptical crack approaching the surface of a semi elliptical solid.
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