On the stress intensity factors associated with cracks interacting with an interface between two elastic media (original) (raw)
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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.
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
Some remarks on elastic crack-tip stress fields
International Journal of Solids and Structures, 1972
It is shown that if the displacement field and stress intensity factor are known as functions of crack length for any symmetrical load system acting on a linear elastic body in plane strain, then the stress intensity factor for any other symmetrical load system whatsoever on the same body may be directly determined. The result is closely related to Bueckner's [1] "weight function". through which the stress intensity factor is expressed as a sum of work-like products between applied forces and values of the weight function at their points of application. An example of the method is given wherein the solution for a crack in a remotely uniform stress field is used to generate the expression for the stress intensity factor due to an arbitrary traction distribution on the faces of a crack. A corresponding theory is developed in an appendix for three-dimensional crack problems, although this appears to be directly useful chiefly for problems in which there is axial symmetry.
International Journal of Engineering Science, 1974
Two half-qucea with different elastic constant< are welded together and subjected to a longitudinal <hear \train at infinity so that the whole ayytem ix in a state of anti-plane strain. Suddenly the weld break\ and a crack hegin\ to propagate at right angle\ to the interface into each of the two media simultaneously with a different velocity in each. Thk paper attempt\ to calculate the resulting stres\ and displ~~enlent fields.
Stress Intensity Factors of an Interface Crack under Polynomial Distribution of Stress
Journal of Solid Mechanics and Materials Engineering, 2010
In this paper, stress intensity factors for a two-dimensional interface crack under polynomial distribution of stress are considered. The problem is formulated as a system of hypersingular integral equations on the idea of the body force method. In this analysis, unknown body force densities are approximated by the products of the fundamental densities and power series; here the fundamental densities are chosen to express singular stress fields due to an interface crack under constant distribution of stress exactly. The stress intensity factors of a 2D interfacial crack under polynomial distribution of stress are expressed as formulas for the reader's convenience with the varying polynomial exponent n. The exact expressions of crack opening displacements are also indicated.
Some Aspects of the Three-Dimensional Interface Cracks Analysis
Tehnicki vjesnik - Technical Gazette, 2020
Many problems of interfacial cracks are three dimensional in nature. Three-dimensional cracks at an interface of the two materials are analysed in this paper. For a crack at an interface, the stress intensity factors, load phase angle and energy release rate depend on elastic characteristics of two bonded materials and on geometry and the load conditions of a bimaterial sample. Influence of Dundurs' parameters on stress intensity factors, load phase angle and energy release rate for different bi-material combinations and for the quarter-circular corner crack are discussed in this paper. Results show that elastic properties of materials constituting the interface have significant influence on behaviour of the 3D interface crack. Mode I stress intensity factor KI increases when the crack front approaches the free surface, while KII remains almost constant having the highest values between 10° and 80°, what results in high values of the load phase angle. The KIII stress intensity factor is zero in the symmetry plane, while its value increases as the crack front approaches free surfaces. The energy release rate diagrams show that the crack of a quarter circular front propagates faster closer to free surfaces than in the middle what means that the crack front would have the tendency of straightening.