The interaction of two parallel non-coplanar identical surface cracks under tension and bending (original) (raw)
Related papers
Materials, 2021
The aim of this study is to obtain the stress intensity factor (SIF) along the crack front of elliptical cracks located in finite-thickness plates subjected to imposed displacement or applied tensile load, for different crack geometries (relative depths and aspect ratios) and crack configurations (embedded, surface, and corner). The SIF was calculated from the J-integral, obtained by the finite element method. The results show how the SIF grows with the increase in the relative crack depth and with the decrease in the aspect ratio, with the corner crack being the most dangerous configuration and the embedded crack the most favorable configuration. By increasing the plate length, the SIF rises when the plate is under imposed displacement and decreases when the plate is subjected to applied tensile load, both cases tending towards the same SIF curve.
Stress intensity factors for interacting cracks
Engineering Fracture Mechanics, 1987
Experimental stress intensity factors (SIFs) for two interacting straight cracks in planehomogeneous regions were determined. Photoelastic data were collected from digitally sharpened isochromatic fringe patterns by using a digital image analysis system. SIFs were extracted by using the field equations derived from Williams' stress function. Numerical SIFs were also obtained by the boundary integral equation method. Good agreement was observed between experimental and numerical results. NOTATION crack tips as shown in Fig. 4 one-half crack length one-half horizontal distance between crack tips A and D one-half vertical distance between crack tips B and C one-half length of specimens specimen thickness one-half width of specimens orientation of crack AB with respect to the long direction of the specimens polar coordinates as shown in Fig. 9 applied far-field tensile stress stress intensity factor mode I SIF mode II SIF term used to normalize SIFs (= o/;;;; in this study) Young's Modulus Poisson's Ratio material fringe value
Frattura ed Integrità Strutturale
In the present work finite element method has been employed to study the interaction of multiple cracks in a finite rectangular plate of unit thickness with cracks on the same side under uniaxial loading conditions. The variation of the stress intensity factor and stress distribution around the crack tip with crack offset distance has been studied. Due to the presence of a neighbouring crack, two types of interactions viz. intensification and shielding effect have been observed. The interaction between the cracks is seen to be dependent on the crack offset distance. It is seen that the presence of a neighbouring crack results in the appearance of mode II stress intensity factor which was otherwise absent for a single edge crack. It can be said that the proximity of cracks is non-desirable for structural integrity. The von-Mises stress for different crack orientations has been computed. Linear elastic analysis of state of stress around the crack tip has also been done.
Stress Intensity Factors For Plates With Collinear And Non-Aligned Straight Cracks
2012
Multi-site damage (MSD) has been a challenge to aircraft, civil and power plant structures. In real life components are subjected to cracking at many vulnerable locations such as the bolt holes. However, we do not consider for the presence of multiple cracks. Unlike components with a single crack, these components are difficult to predict. When two cracks approach one another, their stress fields influence each other and produce enhancing or shielding effect depending on the position of the cracks. In the present study, numerical studies on fracture analysis have been conducted by using the developed code based on the modified virtual crack closure integral (MVCCI) technique and finite element analysis (FEA) software ABAQUS for computing SIF of plates with multiple cracks. Various parametric studies have been carried out and the results have been compared with literature where ever available and also with the solution, obtained by using ABAQUS. By conducting extensive numerical stud...
Stress intensity factors for cracks in structures under different boundary conditions
Engineering Fracture Mechanics, 1990
In calculating stress intensity factor solutions for standard cases, the weight function and superposition technique have been used extensively. These solutions although valid for simple specimens present a problem in the case of statically indeterminate structures. The work described in this paper investigates the effect of boundary conditions on the stress intensity factor solution for an edge cracked plate, edge cracked ring and a surface cracked plate using the finite element technique.
Stress intensity factors for surface cracks in round bar under single and combined loadings
Meccanica, 2011
This paper describes the development and application of a general domain integral method to obtain J-values along crack fronts in three-dimensional configurations of isotropic, functionally graded materials (FGMs). The present work considers mode-I, linear-elastic response of cracked specimens subjected to thermomechanical loading, although the domain integral formulation accommodates elastic-plastic behavior in FGMs. Finite element solutions and domain integral J-values for a two-dimensional edge crack show good agreement with available analytical solutions for both tension loading and temperature gradients. A displacement correlation technique provides pointwise stress-intensity values along semi-elliptical surface cracks in FGMs for comparison with values derived from the proposed domain integral. Numerical implementation and mesh refinement issues to maintain path independent J-values are explored. The paper concludes with a parametric study that provides a set of stress-intensity factors for semi-elliptical surface cracks covering a practical range of crack sizes, aspect ratios and material property gradations under tension, bending and spatially-varying temperature loads.
International Journal of Fracture, 1982
This paper reports on an attempt to investigate the stress intensity factors of equal and unequal oblique parallel edge cracks subjected to tension. The effects of the variation of the length of the cracks, angle of inclination, and crack spacings on the stress intensity factors (opening and sliding modes) were studied. Experimental observations show that, for crack spacings equal or larger than the length of the equal oblique parallel edge cracks, the size of the caustics for the cracks in the loaded specimen approach that of a single oblique edge crack with the same angle of inclination. In the case of unequal oblique parallel edge cracks, a crack closure phenomenon and its occurrance with respect to the length of the cracks and crack spacings were investigated. It was observed that the transverse diameter of the caustic for the shorter cracks became small and negligible when the position of the shorter cracks with respect to the longer cracks became smaller than half of the crack spacings.
Stress Intensity Formulas for Three-dimensional Cracks in the Vicinity of an Interface
Journal of Testing and Evaluation, 2007
In this study, stress intensity formulas are considered in terms of the square root of area parameter to evaluate arbitrary shaped defects or cracks in lhe vicinity of an interface. Here "area" is the projected area of the defect or crack. Stress fatens ity factors for an elliptical crack parallel to a bimaterial interface are considered with varying the distance, aspect ratio of the crack, and combinations of materia l's elastic constants. Also, stress intensity factors of an interface crack and a crack in a functionally graded material are investigated. Then, it is found that the maximum stress intensity factors normalized by the square root of area are always insensitive to the crack aspect ratio. They are given in a form offonnulas useful for engineering applications.