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We first study an arbitrary number of identical parallel screw dislocations evenly distributed along a concentric circle within a nanowire of radius R. Two equilibrium positions, one stable and the other unstable, co-exist for each screw dislocation. As the number of screw dislocations approaches infinity, each will find a stable equilibrium configuration at a distance 0.7071R from the centerline. Next, we investigate a mode III Zener–Stroh central crack in a nanowire. The crack is simulated by a continuous distribution of screw dislocations which leads to a Cauchy-type singular integral equation whose numerical solution results in the stress intensity factor at the crack tip as well as the Eshelby twist of the rod induced by the imaginary screw dislocations comprising the Zener–Stroh crack. The Eshelby twist will significantly reduce the magnitude of the stress intensity factor at the crack tip. [ABSTRACT FROM AUTHOR]

This study deals with the propagation of a semi-infinite crack influenced by SH-wave propagation in an initially stressed dry sandy (ISDS) strip. The Fourier integral transforms (FIT) and Wiener–Hopf (WH) approach are used to solve the model analytically. For the cases of concentrated force of constant intensity (CF) and constant load (CL), the stress intensity factor (SIF) is calculated. The effects of sandiness, crack speed/length, and initial stress on the SIF in ISDS strip are numerically elucidated and graphically demonstrated. Comparison of the SIF analysed for differently configured strips influenced by distinct cases of initial stresses is one of the novel features of this study. [ABSTRACT FROM AUTHOR]

This study developed a procedure for rapidly reconstructing a crack profile for calculating the parameters of fracture mechanics such as stress intensity factor with energy release rate (J) and displacement opening crack tip using data from the eddy current sensor. The inverse problem focused on adopting genetic algorithms to solve the direct problem iteratively. The use of the differential probe allows a rapid and precise resolution of the direct problem. The incident field produced by the two coils is determined using the 3D finite element results and the variation of impedance in each coil due to the crack. For the inverse problem, the crack's surface is considered regular shape in terms of dimensions, and the sensor's impedance expresses the objective function in terms of the width and length of the crack. The evaluation of the shape function and mesh matrix is made dependent on the iterative process, which makes the reversal procedure computationally lightweight when using genetic algorithms. [ABSTRACT FROM AUTHOR]

In this paper, a theoretical model is established to describe the effect of nanoscale amorphization in nanocrystalline bimaterials on the dislocation emission from the tip of a collinear crack at the interface. In the description, nanoscale amorphization is formed by the splitting transition of the Grain Boundary (GB, the disclination of GBs caused by the movement of GBs). The analytical solution of the model is obtained by the elasticity complex potential solution method. In addition, the effects of nanoscale amorphization, dislocation emission angle, interfacial crack length and material constants of nanocrystalline bimaterials on the critical stress intensity factor of interfacial crack tip corresponding to dislocation emission are discussed through numerical analysis. The analysis shows that the influence of nanoscale amorphization in nanocrystalline bimaterials on the critical stress intensity factor (SIF) corresponding to dislocation emission depends on the dislocation emission angle, the position and size of the nanoscale amorphization, interface crack length and relative shear modulus. With the increase in relative shear modulus and dislocation emission angle, the normalized critical SIF decreases at first and increases afterwards. When the nanoscale amorphization size is small, the critical SIF of the dislocation is less affected, but when the size is larger, the impact becomes great. The influence of nanoscale amorphization on the dislocation emission from collinear interface crack tip is related to nanoscale amorphization and relative shear modulus. There is a critical relative shear modulus that the increase in dislocation intensity has little effect on dislocation emission. Appropriate selection of materials for the upper and lower planes can reduce the critical stress intensity factor corresponding to dislocation emission, thereby promoting the dislocation emission from interface cracks and improving the toughness of the nanocrystalline bimaterials. [ABSTRACT FROM AUTHOR]

The paper presents the numerically evaluated dependence of the stress intensity factor (SIF) on crack velocity ( K I - a ˙ dependence) in Homalite-100 specimens subjected to pulse loading. Experiments on crack propagation (Ravi-Chandar and Knauss in Int J Fract 25:247–262, 1984. https://doi.org/10.1007/BF00963460; Int J Fract 26:65–80, 1984. https://doi.org/10.1007/BF01152313; Int J Fract 26:141–154, 1984. https://doi.org/10.1007/BF01157550; Int J Fract 26:189–200, 1984. https://doi.org/10.1007/bf01140627) were simulated using the finite element method and incubation time fracture criterion. According to (Ravi-Chandar and Knauss in Int J Fract 26:141–154, 1984. https://doi.org/10.1007/BF01157550), experimental data on the SIF–crack velocity dependence exhibit unstable behavior, i.e. considerable scattering of the SIF values: a broad range of SIF values corresponds to a single crack velocity. This way, the conventional approach based on a K I - a ˙ dependence being a material property is not applicable in this case. Such a phenomenon is also observed in a numerically obtained K I - a ˙ dependence, meaning that the developed approach makes it possible to evade the known ambiguity of the K I - a ˙ relation to predict the crack propagation. [ABSTRACT FROM AUTHOR]

The present problem aims to study the scattering behavior of SH-waves by a circular cavity near two symmetrically permeable interface cracks in the piezoelectric bi-material half-space. The steady-state response of the problem is obtained, with the aid of the Green's function method and the complex function method. Above all, the essential expression of Green's function is constructed by the mirror method. This expression satisfies the conditions of being stress-free and electric insulation on the horizontal boundary of the orthogonal space where the circular cavity is located, and the condition of bearing a harmonic out-plane line source force on the vertical boundary. Next, on the basis of dividing the bi-material medium into two parts along the vertical boundary, the first kind of Fredholm integral equation with uncertain anti-plane forces is established by using the conjunction method and the crack-division technology. Then, the solution is obtained by solving an algebraic equation with finite terms, which is an effective truncation of the integral equation. Finally, the dynamic stress concentration factor around the edge of the circular cavity and the dynamic stress intensity factor at the crack tip are calculated numerically. On this basis, the effects of incident wave frequency, crack length, crack location and circular cavity position on the dynamic stress concentration factor and dynamic stress intensity factor are discussed. [ABSTRACT FROM AUTHOR]

Determining the stress intensity factor (SIF) for cracked engineering structures under different loading conditions is one of the core issues of fracture analysis. A slender fin-shaped shell possesses both shell and beam characteristics, in the cross section of which some complex cracks, such as the circumferential and T-shaped cracks, may arise. There will be different singular stress fields next to crack tips for a cracked fin-shaped shell under bending. Based on the conservation law and elementary mechanics, a technique to determine SIFs is proposed in this article, which is simple and easy to understand. The SIFs calculated using the present method agree well with FEM results even if elementary mechanics is used. [ABSTRACT FROM AUTHOR]

Solid solution strengthening plays a key role in the strength increasing of alloying metals, due to that a solid solution of alloying element causes lattice distortion to a certain extent. In the paper, the effect of solid solution magnesium additions on the edge dislocation emission from a blunted crack tip in aluminum alloys is investigated. The critical stress intensity factor for the dislocation emission considering different magnesium solute concentrations is analyzed under the mode I and mode II loading conditions. The results show that within a certain concentration range the magnesium solute concentration does affect dislocation emission, although the influence appears not very strong. The critical stress intensity factor for the dislocation emission decreases with the increment of solute concentration. This means that relatively increasing the solute concentration can promote the dislocation emission, cause effective blunting of cracks and thus improve the fracture toughness of materials. [ABSTRACT FROM AUTHOR]

We present a rigorous treatment to the plane problem of a thermoelectric medium with collinear cracks subjected to remote uniform thermal-electric loads based on the complex variable method. First, the general solutions for potential functions of thermoelectric fields and stress fields are derived by using the electrically permeable and thermally insulated crack model. Then, for special cases of one crack and two symmetric cracks, more explicit solutions are given for potential functions and intensity factor of stresses. Finally, numerical results are presented to discuss the effects of applied electric loading on the fracture behavior of thermoelectric media. It is found that the fields of electric flux possess no singularity in the vicinity of the cracks, whereas the thermal flux and stresses exhibit the traditional square-root singularity at the crack tips. In addition, the remote electric current only produces a mode I stress intensity factor. [ABSTRACT FROM AUTHOR]

High-capacity active electrodes, such as Si anodes in Li-ion batteries, undergo a significant volume deformation of up to ∼ 400% during lithiation. Such a huge volume change could cause mechanical fracture and pulverization of electrode materials and result in harmful effects on their electrochemical performance. To have better understanding on this problem, the two-phase lithiation process of hollow core-shell and film structural electrodes is simulated by using a diffusion lithiation model. It is shown that the anisotropic hoop stress is larger than the isotropic one, which may easily induce damage of hollow core-shell negative electrodes. In addition, the anisotropic nature of mechanical properties can also remarkably magnify the edge stress intensity factor of hollow core-shell and film electrodes. These results on the morphological evolution and stress generation shed light on the design of novel and failure-resistant electrodes. [ABSTRACT FROM AUTHOR]

We present a rigorous treatment to the problem of a circular-arc crack in an infinite thermoelectric solid subjected to a combined electrical and thermal loading. Formulating the problem in terms of the complex potentials and reducing it to the Hilbert arc problem, the solutions of quantities in both thermoelectric field and the associated thermoelastic field are presented in a closed form based on the electrically permeable and thermally insulated crack model. The results show that the fields of heat flux, energy flux, and stress exhibit the traditional square-root singularity at tips of arc crack. The applied electric current and energy flux generate both mode I and mode II stress intensity factors (SIFs), which are dependent on the loading direction, electric conductivity, thermal conductivity, central angle of the crack, and thermoelastic isotropy. Electrically induced SIF is a quadratic function of applied electric current density, and thermally induced SIF is a linear function of the imposed total energy flux. In addition, the effects of the loading direction and half crack angle on the thermal SIFs are also presented in a graphic form. This is the first theoretical paper to study the effect of the crack shape on the fracture of fully coupled thermoelectric materials by a rigorous inference of physics and mathematics. [ABSTRACT FROM AUTHOR]

We consider the contribution of fully or partially crack bridging to a mode I or mode II crack perpendicular to a bimaterial interface. The crack faces are subjected to both shear and normal bridging forces, and the bridging stiffnesses are allowed to vary arbitrarily along the crack. The resulting singular integral equations are solved numerically by combining the Chebyshev polynomials and the collocation method. The proposed method is proved reliable and efficient for the bridged crack problem under consideration. It is observed that the stress intensity factors at the two crack tips and the crack opening displacement are suppressed due to the toughening and stiffening effects of crack bridging, respectively. In particular, when the crack is embedded in the right stiffer (or softer) half-plane and is only partially bridged at its left (or right) portion, new phenomena can be observed. More specifically, with suitably chosen bridging zone and bridging stiffness, the behavior of the stress intensity factors and the crack opening displacement for a bridged crack can be quite different from those for an unbridged crack, and the crack can even propagate toward the opposite direction to that for an unbridged crack. [ABSTRACT FROM AUTHOR]

Although the cracking problems of multiferroic structures have been widely investigated, concentrated force-induced fracture still remains as an un-fully explored failure mode that has considerable significance in this field. The present article analyzes the interfacial crack in a layered multiferroic cylinder subjected to a concentrated axial shear force on its outer surface. Themethods of infinite trigonometric-series and Cauchy singular integral equation are applied to solve the problem. The convergence behaviors of the dimensionless infinite trigonometric-series functions are clarified, and the numerical results of stress intensity factor (SIF) are verified by the analytical solution in a special case. Parametric studies are conducted, and the effects of structural parameters on the fracture behavior are revealed. Two structural optimization ways are suggested for reducing the harmful peak value of SIF. One is to decrease the radius of the interface when the total thickness is given, and the other is to increase the layer thickness when the radius of the interface is specified. The obtained conclusions can provide references for anti-fracture optimization of cylindrical multiferroic devices under a concentrated force. [ABSTRACT FROM AUTHOR]

In this investigation, general approximate solutions for the stress intensity factor (SIF) and configuration force (CF) are derived, respectively, based on the Eshelby theory for the interaction between an inhomogeneous inclusion of arbitrary shape undergoing a stress-free transformation strain and plane stress mode II crack. For common inclusion shapes, some simplified approximate formulae are also developed. Then, the relationship between the normalized CF and SIF is discussed, as well as the effects of inclusion shape, location, and size on the CF and SIF of a plane stress mode II crack. To give deep insight into the complex three-dimensional interaction between an inclusion undergoing a stress-free transformation strain and a crack, two typical cases of the triaxial stress state are analyzed, and no significant difference occurs among most engineering materials. [ABSTRACT FROM AUTHOR]

Functional grading (FG) around the crack tip is studied to improve the load capacity in parts made of graded interpenetrating polymer networks (IPN). To calculate the capacity, the stress intensity factor at the crack tip is calculated by blending the displacement correlation technique and finite element solutions. This process is integrated into an optimization process that uses linear scaling to obtain optimal material grading in a fixed domain around the crack tip. The process is demonstrated using a known poly(methyl methacrylate)/polyurethane IPN system for the case of internal and edge cracks. The FG-IPN parts obtained by this optimization show substantially improved load capacity compared to both optimal uniform plates, and plates with simple toughening of the region around the crack. [ABSTRACT FROM AUTHOR]

A theoretical model is developed to investigate the effects of the nanoscale twin and the dislocation pileup at the twin boundary on crack blunting in nanocrystalline materials. In the model, the nanoscale twin as a stress source approximately equals a quadrupole of wedge disclination. Using the complex variable method, the complex form expressions of the stress field and the force field are derived. The critical stress intensity factors (SIFs) for the first dislocation emission from the crack tip are calculated. The effects of the dislocation pileup, disclination strength, twin size, twin orientation, twin position and crack length on the critical SIFs are discussed in detail. Moreover, the shielding/anti-shielding effect produced by the twin, the dislocation pileup at the twin boundary and the first dislocation emitted on the crack tip is discussed. The results show that both the twin and the dislocation pileup at the twin boundary would suppress the dislocation emission from the crack tip. The suppressive effect induced by the dislocation pileup at the twin boundary is much stronger that that by the twin. Meanwhile, the emission angle has a significant effect on the mode I shielding/anti-shielding effect on the crack tip a. [ABSTRACT FROM AUTHOR]

The paper applies dual BIE with crack opening displacements for the calculation of stress intensity factors of a 3D crack. A general transformation is introduced to remove the weak singularity no matter where the source point is located. A singular integration element is subdivided into several quadrilaterals and triangles with fine shapes to ensure the high accuracy of singular integrals. Two types of special crack front elements based on the quadrilateral discontinuous element are proposed to model the distribution of displacements in the vicinity of the crack tips. Results of our method are in very good agreement with the existing results. [ABSTRACT FROM AUTHOR]

A model-III crack under adhesion is studied by non-uniform linear spring models. Employing complex variable method and conformal mapping technique, a closed-form solution is obtained, and an explicit relation between the stress intensity factor and spring stiffness is established. Results show that adhesion reduces the stress intensity factor, and the reduction effect increases with increasing spring stiffness and crack length. As a result of adhesion, the stress intensity factor given by the present model first increases quickly with increasing crack length when the crack length is relatively small, and decreases slowly with increasing crack length after reaching its maximum at a critical crack length. [ABSTRACT FROM AUTHOR]

The problem of the special rotational deformation interacting with an internal crack is studied by developing a theoretical model of deformed nanocrystalline materials. Using the complex variable method of Muskhelishvili and the conformal mapping technique, the expressions of complex potentials and stress fields are obtained analytically. The stress intensity factors (SIFs) near the crack tips and the critical SIFs for the first lattice dislocation emission from the branched crack tip are calculated. The effects of important parameters such as grain size, the length of internal crack, and the angle between the main crack and its branched crack on the critical SIFs for dislocation emission are evaluated in detail. As a result, the special rotational deformation has great influence on the growth of internal crack and the emission of lattice dislocations from the branched crack tip. The disclination quadrupole produced by the special rotational deformation will shield the branched crack tip under a certain condition. Moreover, when the main crack approaches its branched crack, it will stop the emission of lattice dislocations from the branched crack tip. [ABSTRACT FROM AUTHOR]

The general solution of two-dimensional problems in cubic piezoelectric crystals under plane strain condition is derived. The connection between the present solution and that for purely cubic elasticity is established. Accordingly, Eshelby's tensor of an elliptic inclusion is obtained from the corresponding results in orthotropic elasticity. The tensor is expressed explicitly in terms of material constants and shape ratio of the inclusion. As an application, stress concentration problems of an elliptic hole under two different electric conditions (electrically free and electrically clamped) imposed on the end faces of the material are solved by the equivalent inclusion method. Explicit formulas of stress concentration factors are obtained for uniformly applied tension and shear. The link between the stress concentration factor of a slender cavity and the stress intensity factor of the associated slit crack is also developed and discussed. [ABSTRACT FROM AUTHOR]

The existence of crack and notch is a considerable and serious subject in the failure study of solids and structures. As most of cracked domain problems do not have closed-form solutions, numerical methods are dominant approaches dealing with fracture mechanics problems. In fracture mechanics and failure analysis, cracked media energy and consequently stress intensity factors (SIFs) play a crucial and significant role. Based on linear elastic fracture mechanics, the SIFs may be estimated using the energy release rate, as an indirect approach. This study presents the development of a new semi-analytical method to model cracked media. In this method, only the boundaries of problems are discretized using specific higher-order subparametric elements and higher-order Chebyshev mapping functions. Implementing the weighted residual method and using Clenshaw-Curtis quadrature yield diagonal Euler's differential equations. Therefore, when the local coordinate origin is located at the crack tip, the geometry of crack problems is implemented directly without further processing. In order to present crack boundary conditions, a modified form of nodal force function is presented. Validity and accuracy of the proposed method is fully illustrated by four benchmark problems, whose results agree very well with those of other numerical and/or analytical solutions existing in the literature. [ABSTRACT FROM AUTHOR]

In the present work, based on the Dugdale criterion, a closed-form theoretical crack tip driving force model of simple expressions was proposed for static and fatigue crack propagation along a linear yield strength gradient (YSG). Qualitative and quantitative analyses of the YSG effect on the crack tip driving force are given. The crack tip driving force depends on the yield strength at the crack tip, the YSG within the plastic zone and the applied load. A positive (or negative) YSG has a shielding (or amplifying) effect on the crack tip driving force. A difference of material-toughening mechanisms between smooth and sharp strength gradient was revealed both theoretically and numerically. In the linear YSG case, when a fatigue crack propagates along the YSG at a constant applied cyclic crack tip stress intensity factor, the cyclic crack tip opening displacement decreases (or increases) when the crack propagates towards a higher (or lower)-strength region; however, the cyclic crack tip stress intensity factor increases, no matter when the crack propagates towards a higher- or lower-strength region. This abnormal phenomenon causes theoretical and experimental challenges for characterizing the smooth strength gradient effect on the crack tip driving force. [ABSTRACT FROM AUTHOR]

Frictional contact of a rigid punch on a half-plane with shear modulus varying according to an exponential gradient in an arbitrary direction is investigated in this paper. Fourier integral transform method is employed to reduce the current sliding contact problem to a Cauchy-type singular integral equation of the second kind. The contact pressure and the in-plane stress, as well as the stress singularity and the stress intensity factor near both contact edges are obtained, which are further analyzed for different friction coefficients, non-homogeneity parameters and gradient orientation angles. The moment in order to keep the punch moving perpendicularly to the contact surface is also evaluated. All the present results should be helpful for the design of surfaces with strong wear resistance and understanding the mechanical mechanism of graded materials in nature. [ABSTRACT FROM AUTHOR]

Hypersingular integral equations for two intersecting three-dimensional cracks are derived by using Somigliana formula, in which the unknown functions are the displacement discontinuities on the crack-surfaces. The singularity of the unknowns at the crack-front is analyzed by the analytical asymptotic method, and the analytical solutions of the singular stresses near the crack-front are given. Numerical solutions of the stress intensity factors for some examples are presented and discussed. [ABSTRACT FROM AUTHOR]

This study investigates the perpendicular impingement of a normal shock stress wave on three parallel cracks in an infinite medium. The cracks are placed so that two upper collinear cracks are parallel to a lower crack. Using Fourier and Laplace transform techniques, the boundary conditions are reduced to four simultaneous integral equations. In the Laplace domain, the differences in the displacements inside the cracks are expanded in a series of functions that have zero value outside the cracks. The Schmidt method is used to solve the unknown coefficients in the series such that the conditions inside the cracks are satisfied. The stress intensity factors are defined in the Laplace domain, and these are inversed using the numerical method. The stress intensity factors are calculated numerically for some crack configurations. [ABSTRACT FROM AUTHOR]

The mechanical response of a finite circular disc with a central elliptic hole is modelled mathematically assuming that the disc is subjected to radial pressure varying according to a parabolic law along two finite arcs of its periphery. The symmetry axis of the pressure forms an arbitrary angle with respect to the major axis of the elliptic hole. Using the complex potentials technique, the displacement and stress fields are determined in the form of infinite series. Assuming then that the short semi-axis of the elliptic hole tends to zero, compact expressions are obtained for the stress intensity factors characterizing the severity of the stress field around the end points of the ellipse's major axis, which now becomes the tips of a discontinuity resembling a mathematic crack. The solution for the stress intensity factors is validated against the respective one proposed by Atkinson et al. in the limiting case of a centrally cracked disc under diametral compressive point forces. The agreement is very good as long as the length of the crack does not exceed the disc's radius. The novelty of the present solution (besides imposing parabolic pressure instead of uniform one or point forces) is that the discontinuity covers the whole range from the circular hole (ring) to the mathematical crack. Moreover, the expressions obtained are exact, complete and easily programmable. From a practical point of view, the solution introduced can be proven a valuable, easy-to-use tool for engineers using the Brazilian-disc test for the determination of fracture toughness of brittle geomaterials. Indeed, the parabolic pressure considered here approaches closely the actual load distribution exerted on the disc during the standardized implementation of the test. In addition, the form of discontinuity considered here is closer to the shape of the cracks actually machined in the specimens of the test which are by no means mathematical cuts but rather they are slits with a finite distance between their lips. [ABSTRACT FROM AUTHOR]

The general solution of an arbitrarily oriented sub-interface Zener-Stroh crack is derived with the aid of distributed dislocation methods. The crack problem is formulated as a set of singular integral equations and solved numerically so that the stress intensity factor can be evaluated for any orientation angle. To make the facture analysis more accurate, the plastic zone size (PZS) and the crack tip opening displacement (CTOD) are examined by the generalized Irwin model. The plastic zone area is assumed to follow the von Mises yielding criterion and can be related to the stress intensity factors at the crack tips. Numerical examples are given to demonstrate the influence of various parameters, such as material properties, crack-interface distance and loading ratios, on the normalized PZS and CTOD for vertical and parallel crack cases. It is found that the Zener-Stroh crack becomes easier to propagate when it is located in the 'softer' phase of the bi-material structure and parallel to the material interface. If the crack is perpendicular to the interface, it would be much easier for the crack to propagate into the 'softer' side of the structure. [ABSTRACT FROM AUTHOR]

An interfacial imperfection coupling model is proposed to characterize the imperfect interface in a bi-layered multiferroic cylinder by extending the generalized linear spring model of the uncoupled imperfect interface. Based on the model, fracture analysis is performed on the multiferroic cylinder containing intra-layer cracks. Parametric studies on the stress intensity factor (SIF) yield three main conclusions: (a) the mechanical imperfection can enhance the SIF independently; (b) the magnetic or electric imperfection can reduce the SIF only through its coupling with the mechanical imperfection; and (c) the magneto-electric imperfection coupling does not affect the SIF in any case. [ABSTRACT FROM AUTHOR]

This paper presents a new dynamic crack growth prediction tool based upon the symmetric Galerkin boundary element method (SGBEM) in the Laplace domain, combined with the maximum hoop stress (MHS) criterion. The fast Laplace inverse transform developed by Durbin is employed to obtain time-domain solutions of the stress intensity factors required by the MHS criterion. In this work, the proposed Laplace SGBEM tool is used to predict crack trajectories in homogeneous and non-homogeneous isotropic brittle materials under dynamic loading conditions. The effect of the elastic constant mismatches is investigated for the influence of crack-inclusion interaction on crack growth. [ABSTRACT FROM AUTHOR]

Elastic and plastic fracture analysis of a Mode I crack perpendicular to an interface between dissimilar materials is carried out. Continuously distributed dislocations are used to simulate the crack. The simulation will cause singular integral equations with Cauchy kernel. By solving the singular integral equations numerically, the effects of crack depth (distance from the interface to the crack middle point) and Dundurs' parameters on the Mode I stress intensity factor are investigated systematically. Then, based on the Dugdale model, the plastic zone size, and the crack tip opening displacement of the crack under uniform loadings are investigated. The effects of uniform loadings, crack depth, and Dundurs' parameters on the plastic zone size and the crack tip opening displacement are examined. Numerical results show that when the crack is embedded in a stiffer material, the values of both the normalized plastic zone size and the normalized crack tip opening displacement are larger than 1. On the contrary, if the crack is embedded in a softer material, the values of both the normalized plastic zone size and the crack tip opening displacement are less than 1. [ABSTRACT FROM AUTHOR]

This paper presents a numerical method to model a general system containing cracks and voids in an infinite elastic plate under remote cyclic loads. By extending Bueckner's principle suited for a crack to a general system containing cracks and voids, the original problem is divided into a homogeneous problem (the one without cracks and voids) subjected to remote loads and a void-crack problem in an unloaded body with applied tractions on the surfaces of cracks and voids. Thus, the results in terms of the stress intensity factors can be calculated by considering the latter problem, which is analyzed easily by using the hybrid displacement discontinuity method (a boundary element method). Further, a fatigue growth technique of a mixed-mode crack is combined with the numerical approach to simulating a void-crack interaction problem under cyclic loads. Test examples are included to illustrate that the numerical method is very simple and effective for analyzing a void-crack interaction problem. [ABSTRACT FROM AUTHOR]