Effect of crack confi guration on the stress intensity factors for different fracture modes of homogeneous bimaterial: A three-dimensional fi nite element analysis (original) (raw)
Related papers
1979
Methods for obtaining stress intensity factors for bimaterial bodies using numerical crack flank displacement data are presented and compared. The stress analysis of a cracked bimaterial is reviewed. The analysis results in a data reduction scheme for the stress intensity factors via the crack flank displacement data. The data reduction scheme produces adequate resolution of the magnitude of the complex stress intensity factor but is incapable of resolving the angle when the moduli of the adjoining materials are close. An extended form of the J-integral is shown to provide increased accuracy for the magnitude of the complex stress intensity factor without yielding the angle.
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
Stress Intensity Factors for Arbitrarily Located and Oriented Cracks
International Journal of Engineering Research and, 2012
A refined finite element model and a new post processing subprogram to determine mixed mode membrane and bending stress intensity factors for arbitrarily located and oriented cracks in complex shell type structures is presented. A fine mesh of singular isoparametric triangular shell element (STRIA6) with user specified number NS from one crack face to another and size a is created around each crack-tip. The rest of the domain is discretized using a compatible mesh of regular quadratic isoparametric triangular shell element (TRIA6) and quadratic isoparametric quadrilateral shell element (QUAD8). A new post processing subprogram 3MBSIF is presented to compute the Stress Intensity Factors Posteriori. The proposed Finite Element Model implemented using ABAQUS, a unified FEA software, and the new post processing subprogram 3MBSIF are validated using benchmarks, a set of standard test problems with known target solutions. Selected results of a parametric study are presented for arbitrarily oriented cracks of increasing lengths in the toroidal segment of a cylindrical shell with tori-spherical end closures under internal pressure loading.
Stress intensity factors for interface cracks between
2011
Different expressions are used in the literature for the stress intensity factors of interface cracks between anisotropic material. In particular, two of these approaches will be discussed and compared for orthotropic and monoclinic materials. Relations between the stress intensity factors will be found. Expressions for the interface energy release rate G i are presented. Although the expressions appear different, they are shown to be the same by using the relations between the stress intensity factors. Phase angles are defined which may be used in a fracture criterion.
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.
International Journal of Fracture, 2004
Linear elastic fracture mechanics (LEFM) integrated with the interference of fracture surface asperities has been formulated. The asperities are considered to simulate the influence of the microstructures and possibly oxide debris. The applied stress/load-crack opening displacement (COD) relationships in several cases have been derived. In the original LEFM, the stress-COD relationship is represented by a straight line passing through the origin of the stress-COD plot. The insert of one asperity results in a deviation of the stress-COD response from the LEFM relationship, leading to the exhibition of an inflection point (first contact point, σop), a larger slope, and a residual COD. In the case of two asperities, the slope and the residual COD of the stress-COD relationship become further larger, and two inflection points emerge. A general stress-COD expression in the case of multiple asperities has been derived. The slope of the stress-COD equation, the residual COD, and the minimum COD all increase with increasing number of asperities for a given loading condition, resulting in a smaller ΔCOD and Δσeff. The number of the inflection points is the same as that of the asperities. To the authors' knowledge, this paper is the first to derive analytically an applied stress-COD curve with a gradual variation below σop, caused by the asperity-/roughness-, or oxide-induced crack closure.
Interfacial Fracture in the Presence of Residual Stresses
Fracture Mechanics of Ceramics, 1996
At the tip of interface cracks in bimaterials, residual stresses provide strong mode II contributions while four-point-bending loading leads to dominant mode I components of applied stress intensity factors (ASIF). Thermal stress intensity factors (TSIFs) primarily depend on crack length ratio a/w and Oundurs' fIrst parameter a. ASIFs due to bending are mainly dependent on crack length whereas Oundurs' second parameter ß plays a minor role in both, thermal and mechanicalloading cases. In this paper, effective SIFs for combined loading situations are derived and discussed.
Using the Stress Concentration Factor in Determining the Fracture Toughness
Mechanika, 2022
This paper offers the use of stress concentration factor in determining the critical fracture stress and fracture toughness of polymeric composite materials at various crack length ratios. The stress intensity factor has been turned into a function of the stress concentration factor derived from the maximum stress occurring at the notch tip and the tip stress generated by the force applied to the sample. This conver- sion allowed the use of a fixed theoretical radius 1.2732 mm instead of the actual radius of the notch or crack. On the edge cracked three-point bending and tensile samples, the specified method detects the three-point bending fracture stresses with a maximum error rate of 1.2 %. This study also establishes a relationship between the clamped end and the pin-loaded tensile specimens and states that the underlying mechanism of the stress intensity factor of the clamped end tensile specimen is based on the normalization of the stress intensity factor of the pin-loaded conditions with the geo- metric correction factor.