Stress intensity factors for single and double edge cracks in a simple. Paper open access stress intensity factors of double edge. Stress intensity factor solutions and tstresses for internally cracked circular plates were reported in ref. Single edge crack stress intensity factor solutions. Stress intensity factors of double and multiple edge cracks. Stress intensity factors for cracked finite plates with mixed.
Stress intensity factor solutions for multiple edge cracks. Each of the terms accounts for a specific aspect of the crack geometry or loading. The effect of crack position, crack oblique and the kinked crack orientation are investigated to predict if a crack starts to grow. As the stress intensity factor reaches the k ic value, unstable fracture. Using the lefm theory, the interaction between two neighboring crack tips was investigated. Variation of stress intensity factor and crack distance length for double edge crack in human femur bone conference paper pdf available september 2014 with 254 reads how we measure reads. In the present contribution edge cracked and double edge cracked disks are considered.
Two cracks with the same stress intensity will have the same behavior. In order to determine the stress intensity factor, various numerical methods were utilized. These problems are solved by calculating the stress intensity factor sif for mode i ki and ii kii near the crack tip theoretically using mathematical equations and numerically using finite element software. Second, periodic edge cracks are systematically analyzed varying the number, distance and angle of cracks. Mode i and ii stress intensity factors under uniform general biaxial loadings were derived for an inclined edge crack in a semiplane. Stress intensity factor results for the case of circular corner crack obtained by the macroelement technique is presented in this paper. Hence, this paper focuses on how several crack distances, between two parallel edge cracks can affect the value of stress intensity factor k. The effect of crack position, crack oblique and the.
Stress intensity factors and tstress for single and. A double linearspringsmodel is developed in the modal analysis process to describe the breathing oblique crack, and the breathing behaviour of the oblique crack is objectively simulated. Stressintensity factors for semielliptical surface. Stress intensity article about stress intensity by the free. The stress concentration at the very tip of the discontinuity or crack is described by the stress intensity factor ka term used in fracture mechanics. Natural vibration of a beam with a breathing oblique crack. There are various stress intensity factor solutions, particularly for flat plates and pressure vessels with various cracked geometries. Kic has low values for brittle materials, high values for tough materials value 0. Initially, the stress intensity factor of an array of unbridged multiple edge cracks was determined under constant global displacement as well as at a. For problems of purely mode i crack behavior, bowie and freese present the weight function expression as 1 k 1 1 k 1 2 h 2. This is because the right edge is fixed and the left edge is stress free, and the normal compression from the top edge creates an anticlockwise moment, which, similar to the situation in a double cantilever beam subjected to vertical load, forces the upper horizontal crack surface to slide towards the right with respect to the lower. The stress intensity, k i, represents the level of stress at the tip of the crack and the fracture toughness, k ic, is the highest value of stress intensity that a material under very specific planestrain conditions that a material can withstand without fracture.
Stress intensity factors for an inclined edge crack in a. Single edgecrack stress intensity factor solutions. Stressintensity factors for semielliptical surface cracks. Citeseerx comparison between theoretical and numerical. Stress intensity factors tstresses weight functions.
In the present contribution edgecracked and doubleedgecracked disks are considered. The stress intensity factor for edge crack in finite plate can be achieved by the formula 3 when 1 h b. Revised october 9, 2019 elasticity solutions to the stress intensity factors sifs of orthotropic double cantilever beams dcbs under antiplane cracking. Some of these solutions are based on the use of thinshell theory18, which does not take into account the three dimensional nature of the highly localised stresses in the vicinity of the crack front. Rather than deal with giant stress concentrations, fracture mechanics uses a stress intensity factor, k. Pdf the stress intensity factor of hole edge cracks in a. The derived weight functions account for both the global weldment geometry and the weld profile characterised by the weld angle. By interpolating finite element results in the angular range 0.
The stress intensity factor is generally expressed in the form k y. The results are compiled in the form of tables, figures and approximate relations. Sep 10, 2012 this note deals with the stress intensity factors sifs for double edge halfcircularhole cracks in a rectangular sheet in tension by means of the displacement discontinuity method with crack tip elements a boundary element method proposed recently by the author. The stress intensity factor for two cracks of unequal length at the edge of an elliptical hole increases with the crack length and the majortominor axis ratio of the elliptical hole. The simplest geometry factor is that for an edge crack of length, a, at the edge of a. Thus, the cracks within human bones are quite complicated because of the bone microstructure.
Stress intensity factors and tstress for single and double. The y term allows the effects of finite width, crack shape, position along crack front, bulging, stress concentration factors, local stress concentration due to welds, etc. Weight function arguments and a boundary collocation technique are used to reexamine the stress intensity factor solutions to several classic twodimensional linear elastic single edge crack configurations. A finite rectangular plate with double edge crack under uniaxial tension depends on the assumptions of linear elastic fracture mechanics lefm and plane strain problem are studied in the present paper. The calculation of stress intensity factors for the single edge cracked. An analytical method is proposed to calculate the natural frequency of a cantilever beam with a breathing oblique crack. Stress intensity factors and t stress solutions for components containing single and double edge cracks were computed predominantly by application of the boundary collocation method, the fracture mechanics weight function and a greens function for tstresses. Understanding limitations and the power of knowledge. The stress intensity factor sif of crack a is found to be almost constant independent of inclination angle b if the tip of crack b is fixed. Stress intensity factors of double edge cracks in large groove plates under mode i tension a e ismail1, m a azlan 1, m l m tobi and m h ahmad2 1faculty of mechanical and manufacturing engineering, universiti tun hussein onn malaysia, batu pahat, johor, malaysia. A set of complex functions for the double edge cracked plate is proposed. The correction factors for various geometrical conditions under a given load. Analysis of stress intensity factors for an edge cracked tsection in tension by.
An empirical formula for stress intensity factors of double. Crack tip stress dependence on the stress intensity factor k s y x w xy v yy v xx m u y r a s s s 3 yy 2 k x v s 2 yy 2 k x v s k 1 c. Aem 535 hw10 jcontour for lefm stress intensity factors. In this paper, based on a huge amount of numerical analysis, an empirical formula of stress intensity factors sifs for cracks initiated from the interface edge with various directions and crack length has been proposed. Srawley and bernard gross lewis research center summary cracklineloaded edgecrack specimens are flat plate specimens which have a single crack notch extending normally from one edge and which are loaded in tension at posi tions close to the intersection of the. This last step involves modelling the crack itself as a distribution of the derived dislocation solutions for the strip. Mixedmode stress intensity factors for a crack in an. A method for calculating stress intensity factors for edge and surface cracks in weldments has been presented. Stress intensity factor for a corner crack at the edge of a. Stress intensity factors for cracklineloaded edgecrack. The finite element method fem analysis software abaqus is used to calculate the. The stress intensity factor is calculated for a given geometry and load, and compared with a threshold value of k above which cracks will propagate in the given material. 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.
The stress intensity factor for a double edge cracked plate by. Stress intensity factors of double edge cracks in large groove plates under mode i tension. It is a theoretical construct usually applied to a homogeneous, linear elastic material and is useful for providing a failure criterion for brittle materials. Therefore, it must be calculated accurately to obtain the fracture damage. Crack tip stress dependence on the stress intensity factor k s y x w xy v yy v xx m u y r a s s s 3 yy 2 k x v s 2 yy 2 k x v s k 1 stress components, v ij, at the crack tip depend on the stress intensity factors k i which is influenced by. Hence, this paper focuses on how several crack distances, between two parallel edge cracks can affect the value of stress intensity factor. Finite element method analysis of stress intensity factor in. Stress analysis, crack propagation and stress intensity factor computation of a ti6al4v aerospace bracket using ansys and franc3d. Influence coefficients were defined in the crack reference frame thus highlighting the coupling. Stress intensity factor for a corner crack at the edge of. Solution due to the stress concentration near the circular hole k t 3 an element at the rim of the hole is subjected to a tensile stress 3. This page provides the sections on the stress intensity factor from wang, c. The theory of linear elastic fracture mechanic lefm has proven that we can evaluate the amount of stress located at the crack tip by determining the stress intensity factor.
From figure 3, it can be seen that as, sif is larger than 0. This section will present a catalog of stress intensity factor solutions for some typical crack geometries. The general form of the stress intensity solution for any crack can be described as. Stress intensity factors and weight functions for special crack problems. Thus, a small edge crack having the size a a a b 3 has an equivalent stress intensity factor with a large pennyshaped crack. Results for the remote tension loading are compared with those obtained by the boundaryintegral equation bie method and threedimensional finiteelement technique based on singular elements. Empirical formula for stress intensity factor of crack. An empirical formula for stress intensity factors of. Variation of stress intensity factor and crack distance. Stress intensity factors of double edge cracks in large. For a through edge crack in a uniform stress field m s. 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. Gentilcore a thesis j presented to the graduate and research committee of lehigh university in candidacy for the degree of master of science in mechanical engineering and mechanics lehigh university may 21, 1993. Analysis of stress intensity factors for an edge cracked t.
Stress intensity factor solutions for multiple edge cracks in. Msc theses, rensselaer polytechnic institute, hartford, 2011. Pdf variation of stress intensity factor and crack distance length. Many of these solutions are found in computer programs and handbooks. Stress intensity factors of double and multiple edge. Apr 01, 2017 stress intensity factor determination for double edge cracked plate with abaqus using j contour integral, comparison to accepted solution. Pdf variation of stress intensity factor and crack. However, this evaluation method is inconvenient for engineering application due to its complicity. Variation of stress intensity factor and crack distance length for double edge crack in human femur bone. Initially, the stress intensity factor of an array of unbridged multiple edge cracks was determined under constant global displacement as well as at a point load along the crack wake. This paper deals with determination of the stress intensity factor mode i ki for centre craked tension cct, single edge notch tension sent and double edge notch tension dent finite platesunder linear elastic fracture mechanics lefm and plane strain assumptions. Pdf variation of stress intensity factor and crack distance. Including the singular and the first regular stress term, the neartip stress field for a modei crack can be expressed by 1.
Approximate determination of stress intensity factor for. The y term allows the effects of finite width, crack shape, position along crack front, bulging, stress concentration factors, local stress concentration. Dtdhandbook summary of stress intensity factor information. The boundary collocation method is used for estimating the stress intensity facto. The distribution of the stress near the tip of a radial crack at the edge of a circular hole, international journal of engineering science, vol. This represents the effective local stress at the crack tip. Stress intensity factors for cracklineloaded edgecrack specimens by john e. A2, the stress intensity factor for a pennyshaped crack with diameter 2 a b d 2.
The weight function method was applied and appropriate weight functions have been derived using the petroskiachenbach crack opening displacement expression. The solutions are categorized by the location of the crack, either embedded, in a plate surface or edge, or at a hole, in tables 11. Analysis of stress intensity factors for an edge cracked t section in tension. Stressintensity factor results for the case of circular corner crack obtained by the macroelement technique is presented in this paper. This section will present a catalog of stressintensity factor solutions for some typical crack geometries. Fatigue crack stress intensity factor crack length. The methods were the boundary element method 8,9, the meshless method 10,11, the finite element method 5, 1220, and virtual crack extension 21,22. The stress at the tip of a sharp crack has the highest stress which can lead to failure on the material. Using the lefm theory, the interaction between two. A procedure is presented for determining stress intensity factors for single and double edge cracks in simply supported undamped bernoullieuler beams under. The interaction effect is found to occur mostly due to the distance independent of the angle. Mixedmode stress intensity factors for a crack in an anisotropic bimaterial strip l.
758 405 464 593 689 323 1572 1447 1115 847 875 455 424 1202 542 1420 801 539 511 279 1436 1553 343 1213 466 1264 1242 482 658 371 78 665 576 1425 1188 215 176 397 1134 273 945 1173 1138 216 769 574 296 185 894 374