The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Qihong Fang - One of the best experts on this subject based on the ideXlab platform.
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crack interaction with a second phase nanoscale Circular Inclusion in an elastic matrix
International Journal of Engineering Science, 2013Co-Authors: Qihong Fang, Youwen LiuAbstract:The screw dislocation interacting with a nanoscale Circular Inclusion and a mode III crack is studied considering the importance of interface stress in controlling mechanical response of nanoscale composite structures. By using the complex potential function method, the image force and the stress intensity factor at the tip of the crack produced by the screw dislocation are obtained under an applied remote load. The results indicate that the shielding effect on the stress intensity factor due to the screw dislocation is enhanced (abated) by the negative (positive) interface stress, and increases (decrease) with an increase of the ratio of the shear modulus of the matrix over that of the Inclusion (the relative length of the Inclusion). The soft (stiff) Inclusion promotes (suppresses) the crack extension. In addition, the surface of the nano-Inclusion forms a tensional (compression) image force for the positive (negative) interface stress. It is also found that the interface stress generates strong sizedependence of the image force, comparing with the classical solution where this force is always constant.
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Piezoelectric screw dislocations interacting with a Circular Inclusion with imperfect interface
Archive of Applied Mechanics, 2007Co-Authors: B. Jin, Qihong FangAbstract:The electroelastic coupling interaction between multiple screw dislocations and a Circular Inclusion with an imperfect interface in a piezoelectric solid is investigated. The appointed screw dislocation may be located either outside or inside the Inclusion and is subjected to a line charge and a line force at the core. The analytic solutions of electroelastic fields are obtained by means of the complex-variable method. With the aid of the generalized Peach–Koehler formula, the explicit expressions of image forces exerted on the piezoelectric screw dislocations are derived. The motion and the equilibrium position of the appointed screw dislocation near the Circular interface are discussed for variable parameters (interface imperfection, material electroelastic mismatch, and dislocation position), and the influence of the nearby parallel screw dislocations is also considered. It is found that the piezoelectric screw dislocation is always attracted by the electromechanical imperfect interface. When the interface imperfection is strong, the impact of material electroelastic mismatch on the image force and the equilibrium position of the dislocation becomes weak. Additionally, the effect of the nearby dislocations on the mobility of the appointed dislocation is very important.
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analysis of a piezoelectric screw dislocation in the interphase layer between a Circular Inclusion and an unbounded matrix
Materials Chemistry and Physics, 2006Co-Authors: Yachao Liu, Qihong Fang, C P JiangAbstract:Abstract The electroelastic interaction of a piezoelectric screw dislocation in the interphase layer with a Circular Inclusion and an unbounded matrix is dealt with. An efficient and concise method for complex multiply connected region is developed by combining the sectional holomorphic function, Schwartz symmetric principle, Cauchy-type integral and Laurent series expansion techniques, in terms of which explicit series form solutions of the complex potentials in the matrix, the interphase layer and the Inclusion regions are derived. The image force acting on the piezoelectric screw dislocation is also calculated by using the generalized Peach–Koehler formula. The influence of the elctroelastic properties of the materials and the relative thickness of the interphase layer on the image force is discussed and shown in graphs. The results show that the above factors can drastically affect the motion of the dislocation in the interphase layer. In addition, a fundamental solution is provided in this paper to further investigate the problem involving interfacial defects and the dislocation mechanism. The present solutions contain a number of novel and previously known results which can be shown to be special cases.
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A wedge disclination dipole interacting with a Circular Inclusion
physica status solidi (a), 2006Co-Authors: Yang Liu, Qihong Fang, C P JiangAbstract:The problem involving the interaction effects between a wedge disclination dipole and an elastic Circular Inclusion is investigated. Utilizing the Muskhelishvili complex variable method, the closed form solutions are derived for complex potentials and stress fields due to a wedge disclination dipole located near the Circular Inclusion. The strain energy and the force acting on the disclination dipole center are also calculated. The influence of the orientation and the location of the disclination dipole as well as the material elastic dissimilarity upon the equilibrium position of the disclination dipole is discussed in detail. The results show that for certain combinations of materials constants, the disclination dipole has a stable equilibrium point near the Inclusion. Moreover, the force on the disclination dipole is very much affected by the orientation of the disclination dipole. The present solutions contain previously known results as the special cases. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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a screw dislocation in a three phase composite cylinder model with interfacial rigid lines
Acta Mechanica Solida Sinica, 2005Co-Authors: Qihong Fang, Youwen LiuAbstract:The problem of the elastic interaction between a screw dislocation and a three-phase Circular Inclusion with interfacial rigid lines (anti-cracks) is investigated. An efficient and concise method for the complex multiply connected region is developed, with which explicit series form solutions of the complex potentials in the matrix, and the interphase layer and Inclusion regions are derived. Based on the complex potentials, the image force on the screw dislocation is then calculated by using the Peach-Koehler formula. The equilibrium position of the dislocation is discussed in detail for various rigid line geometries, interphase layer thicknesses and material property combinations. The main results show that the interfacial rigid lines exert a significant perturbation effect on the motion of the screw dislocation near the Circular Inclusion surrounded by an interphase layer.
Y.w. Liu - One of the best experts on this subject based on the ideXlab platform.
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a piezoelectric screw dislocation in a three phase composite cylinder model with electrically conductive interfacial rigid lines
Journal of Intelligent Material Systems and Structures, 2006Co-Authors: Q H Fang, Y.w. LiuAbstract:The problem of the electro-elastic coupling interaction between a piezoelectric screw dislocation and a three-phase Circular Inclusion with interfacial electrically conductive rigid lines (anti-cracks) is investigated. An efficient and concise method for complex multiply connected region is developed, in terms of which explicit series form solutions of the complex potentials in the matrix, the interphase layer and the Inclusion regions are derived. Based on the complex potentials, the image force on the piezoelectric screw dislocation is then calculated by using the generalized Peach–Koehler formula. The equilibrium position of the dislocation is discussed in detail for various rigid line geometries, intrephase layer thicknesses, and piezoelectric material property combinations. The main results show that the interfacial rigid lines have significant perturbation effect on the motion of the piezoelectric screw dislocation near the Circular Inclusion surrounded by an interphase layer. The solutions of compl...
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a piezoelectric screw dislocation interacting with an interphase layer between a Circular Inclusion and the matrix
International Journal of Solids and Structures, 2004Co-Authors: Y.w. Liu, Qihong Fang, C P JiangAbstract:Abstract The interaction of a piezoelectric screw dislocation with an interphase layer between the Circular Inclusion and the piezoelectric matrix is dealt with. An efficient method for multiplying connected region is developed by combining the sectional holomorphic function, Cauchy-type integral and Laurent series expansion techniques, in terms of which the relation among the complex potentials for the three material regions is obtained. The functional equation in complex potentials for the interphase layer is derived, resulting in explicit series solutions for the two cases when piezoelectric screw dislocation is located in the matrix or in the Inclusion. The image force acting on the piezoelectric screw dislocation is calculated by using the generalized Peach–Koehler formula. Three practical cases are provided to investigate the influence of the interphase layer parameters on the image force. The present solutions contain a number of novel and previously known results which can be shown to be special cases.
C P Jiang - One of the best experts on this subject based on the ideXlab platform.
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the coupling interaction of a screw dislocation with a bimaterial interface and a nearby Circular Inclusion
Archive of Applied Mechanics, 2015Co-Authors: Hui Chai, C P Jiang, Fan Song, Jia LiAbstract:This work deals with the coupling interaction of a screw dislocation with a bimaterial interface and a nearby Circular Inclusion. Explicit series solutions are obtained by the complex potential and conformal mapping technique. Then the solutions are cast into new expressions with the coupling interaction effects separated. The new expressions converge rapidly and provide good first-order approximation formulae. The interaction energy and image force fields are formulated, evaluated, and shown graphically. It is found that the Inclusion severely distorts the neighboring interaction energy contours and image force lines. There must be one unstable equilibrium point in Material 2 where the Inclusion is located, whereas there may be zero, one or two equilibrium points (stable or unstable) in Material 1 without any Inclusion, which depends on a combination of three material shear moduli and the nondimensional distance between the Inclusion and bimaterial interface. It is interesting to notice that the direction of some local image forces in Material 1 may be inversed by a nearby Inclusion in Material 2, and the inverse region is close to but not connected to the bimaterial interface.
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analysis of a piezoelectric screw dislocation in the interphase layer between a Circular Inclusion and an unbounded matrix
Materials Chemistry and Physics, 2006Co-Authors: Yachao Liu, Qihong Fang, C P JiangAbstract:Abstract The electroelastic interaction of a piezoelectric screw dislocation in the interphase layer with a Circular Inclusion and an unbounded matrix is dealt with. An efficient and concise method for complex multiply connected region is developed by combining the sectional holomorphic function, Schwartz symmetric principle, Cauchy-type integral and Laurent series expansion techniques, in terms of which explicit series form solutions of the complex potentials in the matrix, the interphase layer and the Inclusion regions are derived. The image force acting on the piezoelectric screw dislocation is also calculated by using the generalized Peach–Koehler formula. The influence of the elctroelastic properties of the materials and the relative thickness of the interphase layer on the image force is discussed and shown in graphs. The results show that the above factors can drastically affect the motion of the dislocation in the interphase layer. In addition, a fundamental solution is provided in this paper to further investigate the problem involving interfacial defects and the dislocation mechanism. The present solutions contain a number of novel and previously known results which can be shown to be special cases.
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A wedge disclination dipole interacting with a Circular Inclusion
physica status solidi (a), 2006Co-Authors: Yang Liu, Qihong Fang, C P JiangAbstract:The problem involving the interaction effects between a wedge disclination dipole and an elastic Circular Inclusion is investigated. Utilizing the Muskhelishvili complex variable method, the closed form solutions are derived for complex potentials and stress fields due to a wedge disclination dipole located near the Circular Inclusion. The strain energy and the force acting on the disclination dipole center are also calculated. The influence of the orientation and the location of the disclination dipole as well as the material elastic dissimilarity upon the equilibrium position of the disclination dipole is discussed in detail. The results show that for certain combinations of materials constants, the disclination dipole has a stable equilibrium point near the Inclusion. Moreover, the force on the disclination dipole is very much affected by the orientation of the disclination dipole. The present solutions contain previously known results as the special cases. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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a piezoelectric screw dislocation interacting with an interphase layer between a Circular Inclusion and the matrix
International Journal of Solids and Structures, 2004Co-Authors: Y.w. Liu, Qihong Fang, C P JiangAbstract:Abstract The interaction of a piezoelectric screw dislocation with an interphase layer between the Circular Inclusion and the piezoelectric matrix is dealt with. An efficient method for multiplying connected region is developed by combining the sectional holomorphic function, Cauchy-type integral and Laurent series expansion techniques, in terms of which the relation among the complex potentials for the three material regions is obtained. The functional equation in complex potentials for the interphase layer is derived, resulting in explicit series solutions for the two cases when piezoelectric screw dislocation is located in the matrix or in the Inclusion. The image force acting on the piezoelectric screw dislocation is calculated by using the generalized Peach–Koehler formula. Three practical cases are provided to investigate the influence of the interphase layer parameters on the image force. The present solutions contain a number of novel and previously known results which can be shown to be special cases.
Xu Wang - One of the best experts on this subject based on the ideXlab platform.
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a concentrated couple inside or outside a Circular Inclusion in finite plane elastostatics
International Journal of Non-linear Mechanics, 2018Co-Authors: Xu Wang, Liang Chen, Peter SchiavoneAbstract:Abstract We consider a Circular elastic Inclusion embedded in an infinite matrix each from a particular class of compressible hyperelastic materials of harmonic type. A concentrated couple is applied either inside the Circular Inclusion or in the matrix. Closed-form solutions of the corresponding boundary value problems are obtained using complex variable methods, in particular the principle of analytic continuation. Our analysis reveals several interesting conclusions including: the sum σ 11 + σ 22 of the normal stresses inside the Inclusion remains constant when the concentrated couple is located in the surrounding matrix; the sum of the normal stresses is zero everywhere in the matrix when the concentrated couple is located inside the Inclusion.
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A Circular Inclusion with imperfect interface in finite plane elastostatics
Acta Mechanica, 2011Co-Authors: Xu WangAbstract:We consider a Circular elastic Inclusion embedded in a particular class of harmonic materials subjected to remote uniform stresses. The imperfect interface can be rate dependent as well as rate independent. First, we study the situation in which both rate-depending slip and diffusional relaxation are present on the sharp Inclusion-matrix imperfect interface. It is found that in general, the internal Piola stresses within the Inclusion are spatially non-uniform and decay with two relaxation times. Interestingly, the average mean Piola stress within the Circular Inclusion is time independent. Some extreme cases for the imperfect interface are discussed in detail. Particularly, we find a simple condition leading to internal uniform Piola stresses that decay only with a single relaxation time. Second, we investigate a rate-independent spring-type imperfect interface on which normal and shear tractions are proportional to the corresponding displacement jumps. It is found that in general, the internal Piola stresses are intrinsically non-uniform. A special kind of the spring-type interface leading to internal uniform Piola stresses is also found.
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Interaction between an edge dislocation and a Circular Inclusion with interface slip and diffusion
Acta Materialia, 2010Co-Authors: Xu WangAbstract:We investigate in detail the transient response induced by an edge dislocation near a Circular elastic Inclusion with simultaneous interface slip and diffusion. A rigorous solution to the interaction problem is derived in series form. As the time approaches infinity, our solution just recovers the classical one derived by Srolovitz et al. (Acta Metall 1984;32:1079) for fully relaxed boundary conditions. In addition, we observe that the edge dislocation will induce a uniform rigid-body rotation in the Inclusion as the time approaches infinity. When the dislocation is far away from the Inclusion, simple asymptotic expressions of the glide and climb forces on the dislocation are also obtained. Furthermore, five extreme cases for the imperfect interface are discussed; in particular, we derive approximate closed-form expressions of the decaying internal stress field within the Inclusion and the image force on the dislocation for long-range stress relaxations when the interface diffusion occurs much faster than the interface slip and vice versa. Some interesting physical behaviors are observed.
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interaction between an edge dislocation and a Circular Inclusion with an inhomogeneously imperfect interface
Mechanics Research Communications, 2006Co-Authors: Xu WangAbstract:Abstract This research presents an analytical study of the interaction problem of an edge dislocation with a Circular Inclusion with a circumferentially inhomogeneously imperfect interface. The interface, which is modeled as a spring (interphase) layer with vanishing thickness, is characterized by that in which there is a displacement jump across the interface in the same direction as the corresponding tractions, and the same degree of imperfection is realized in both the normal and tangential directions. Furthermore, the interface parameter is nonuniform along the interface. In order to arrive at an elementary form solution, we introduce a conformal mapping function. Then the stress field as well as the Peach–Koehler force acting on the edge dislocation can be obtained from the derived complex potentials. Calculations demonstrate that the nonuniform interface parameter has a significant influence on the stress field.
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on double Circular Inclusion problem in antiplane piezoelectricity
International Journal of Solids and Structures, 2001Co-Authors: Xu Wang, Yapeng ShenAbstract:In this paper, an analytical solution in series form for the problem of double Circular piezoelectric Inclusions embedded in an infinite piezoelectric matrix is presented within the framework of linear theory of piezoelectricity. The matrix is subjected to remote electro-mechanical loading, and the three phase system is also subjected to the action of arbitrary singularities. The solution is obtained by applying complex potential approach in conjunction with the techniques of conformal mapping, analytical continuation, singularity analysis, Laurent's series expansion in an annular ring region and Cauchy integral formulae, etc. Based on the obtained complex potentials, explicit expressions for the stress and electric displacement in the matrix and the two Circular Inclusions are also derived. A numerical investigation for the case of remote loading is performed to illustrate the influence of a third phase on the system's electroelastic coupling behavior and also to verify the correctness and usefulness of the solution.
Z M Xiao - One of the best experts on this subject based on the ideXlab platform.
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on the interaction between a full craze and a near by Circular Inclusion in glassy polymers
Engineering Failure Analysis, 2017Co-Authors: Yan Mei Zhang, M Fan, Wengang Zhang, Z M XiaoAbstract:Abstract Crazing is the common reason in polymer composites to cause failure. So far research work on craze phenomenon has been done only in homogenous polymer materials. The first time in our current study, the stress analysis has been carried out on the interaction between a Circular Inclusion and a full craze in polymer composites. A craze can be treated as a crack with fibrils bridging the two crack surfaces. The forces applied by the bridging fibrils to the crack surfaces (pulling the two surfaces closer) depend on the crack opening displacement, while the crack opening displacement is directly related on the forces applied by the bridging fibrils. To solve this dilemma, an iterative procedure is created and introduced to solve the formulated singular integral equations. The influences of the Inclusion's elastic properties on the craze thickness profile and the stress intensity factors are investigated in details. It is found that the case with a “stiffer” Inclusion produces smaller craze thickness. Also, the craze thickness profile is strongly affected by the Inclusion size and the craze-Inclusion distance. The shielding effect of a stiffer Inclusion on the craze is discussed by evaluating the stress intensity factors at both craze tips.
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stress investigation on a cracked craze interacting with a nearby Circular Inclusion in polymer composites
Acta Mechanica, 2017Co-Authors: Yan Mei Zhang, M Fan, Wengang Zhang, Z M XiaoAbstract:In polymer composites, Inclusions (fillers) are introduced into the glassy polymeric matrices in order to improve the toughness properties as the brittleness is one of the fatal drawbacks for glassy polymers. For the first time, in our current study, the stress analysis has been performed on the interaction between a Circular Inclusion and a craze with an internal small crack in polymeric composites. A craze can be treated as a crack with fibrils bridging the two crack surfaces. The forces applied by the fibrils to the crack surfaces (pulling the two surfaces closer) depend on the crack opening displacement. However, the crack opening displacement is directly related to the forces applied by the craze fibrils. To solve this dilemma, an iterative procedure is proposed for the first time to solve the formulated singular integral equations. The craze thickness profiles, the cohesive stress distribution, and the fracture toughness of the polymeric composites are investigated thoroughly. Moreover, due to the influence of the Inclusion, the uneven craze thickness profiles are observed from the left to the right part of the entire craze zone.
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plastic zone correction on a zener stroh crack interacting with a Circular Inclusion in ductile materials
Fatigue & Fracture of Engineering Materials & Structures, 2016Co-Authors: M Fan, Z M XiaoAbstract:Elastic–plastic stress analysis on a matrix Zener–Stroh crack interacting with a Circular Inclusion (fibre) in fibre-reinforced composites has been carried out. The Zener–Stroh crack is initiated near the fibre in the pure matrix. Plastic zone correction is introduced the first time for such a crack–Inclusion interaction problem so that the fracture behaviour can be analysed more accurately. To determine the plastic zone sizes, a generalized Irwin model is proposed for the mixed-mode problem where the Von Mises stress yielding criterion is employed. Different to a Griffith crack, a Zener–Stroh crack propagation always occurs from the sharp tip whose relative position to the Inclusion has great effect on the elastic–plastic fracture behaviour of the crack. In our study, the plastic zone size (PZS), crack tip opening displacement (CTOD) and effective stress intensity factor (SIF) are evaluated by solving the formulated singular integral equations. Through the numerical examples, the influence of the Inclusion (fibre) shear modulus, crack–Inclusion distance and the crack sharp tip position on the fracture behaviour of the crack is discussed. It is found that the shear modulus ratio and the crack–Inclusion distance have great effect on the normalized values of PZS and CTOD, but the effects highly depend on the crack sharp tip position.
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generalized irwin plastic zone correction for a griffith crack near a coated Circular Inclusion
International Journal of Damage Mechanics, 2015Co-Authors: M Fan, Z M XiaoAbstract:Elastic-plastic stress analysis on a radial crack interacting with a coated-Circular Inclusion in a matrix has been carried out with the aid of a generalized Irwin plastic zone correction. The crack line is assumed to be at the angle of 90° − θ from a remote tensile loading. In the mathematical formulation, the distributed dislocation method is used to simulate the crack. By solving a set of singular integral equations, three quantities, the effective stress intensity factor, the plastic zone size and the crack tip opening displacement (CTOD), are evaluated with the generalized Irwin model proposed. Numerical examples are given to show the influence of the key parameters such as the crack orientation angle θ, the normalized crack distance, the normalized coating phase thickness and the shear modulus ratio (μ2/μ3, coating phase/matrix) on the fracture behavior. The results indicate that the influence of angle θ is the greatest, while the effect of shear modulus ratio μ2/μ3 is relatively small. A validation...
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plastic zone size and crack tip opening displacement of a dugdale crack interacting with a coated Circular Inclusion
Philosophical Magazine, 2010Co-Authors: Hsin Jen Hoh, Z M Xiao, J LuoAbstract:An analytical investigation on the plastic zone size of a crack near a coated Circular Inclusion under three different loading conditions of uniaxial tension, uniform tension and pure shear was carried out. Both the crack and coated Circular Inclusion are embedded in an infinite matrix, with the crack oriented along the radial direction of the Inclusion. In the solution procedure, the crack is simulated as a continuous distribution of edge dislocations. With the Dugdale model of small-scale yielding [J. Mech. Phys. Solids 8 (1960) p. 100], two thin strips of yielded plastic zones are introduced at both crack tips. Using the solution for a coated Circular Inclusion interacting with a single dislocation as the Green's function, the physical problem is formulated into a set of singular integral equations. Using the method of Erdogan and Gupta [Q. J. Appl. Math. 29 (1972) p. 525] and iterative numerical procedures, the singular integral equations are solved numerically for the plastic zone sizes and crack tip...