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Dai Ning Fang - One of the best experts on this subject based on the ideXlab platform.
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propagation of a mode iii Interfacial Crack in a piezoelectric piezomagnetic bi material
International Journal of Solids and Structures, 2012Co-Authors: Haosen Chen, Weiyi Wei, Jinxi Liu, Dai Ning FangAbstract:The transient response of a semi-infinite mode-III Interfacial Crack propagating between piezoelectric (PE) and piezomagnetic (PM) half spaces is investigated in this paper. The integral transform method together with the Wiener–Hopf and Cagniard–de Hoop techniques is used to solve the mixed boundary value problem under consideration. The existence of generalized Maerfeld–Tournois Interfacial wave is discussed and the solutions of the coupled fields are derived for four different cases of bulk shear wave velocity. The dynamic intensity factors of stress, electric displacement and magnetic induction as well as energy release rate (ERR) are obtained in explicit forms. The numerical results of the universal functions and dimensionless ERR for several different material combinations are presented and discussed in details. It is found that the Bleustein–Gulyaev (generalized Maerfeld–Tournois) waves dominate the dynamic characteristics of the Interfacial Crack propagation in PE–PM bi-material.
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a screw dislocation interacting with an Interfacial Crack in two dissimilar piezoelectric media
Physica Status Solidi B-basic Solid State Physics, 2002Co-Authors: A K Soh, Jinxi Liu, Dai Ning FangAbstract:In this paper the interaction of a screw dislocation with a semi-infinite Interfacial Crack of two dissimilar piezoelectric materials is considered. The expressions for the electroelastic fields, intensity factors, and image force acting on a screw dislocation are given in explicit form in terms of complex functions. When one of two materials is purely elastic, the influence of electromechanical coupling on the stress intensity factor and the image force is analyzed in detail. In addition, the results obtained in the present paper can be reduced to several special cases that have been reported previously in the literature.
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Analysis of a bi-piezoelectric ceramic layer with an Interfacial Crack subjected to anti-plane shear and in-plane electric loading
European Journal of Mechanics A Solids, 2000Co-Authors: Ai Kah Soh, Dai Ning Fang, Kwok Lun LeeAbstract:The behaviour of a bi-piezoelectric ceramic layer with a centre Interfacial Crack subjected to anti-plane shear and in-plane electric loading has been studied. The dislocation density functions and the Fourier integral transform method have been employed to eliminate the problem of singular integral equations. The normalized energy release rate, stress and electrical displacement intensity factors, G/G0, KIII/KIII0and KD/KD0, respectively, were determined for different geometric and property parameters by use of two different Crack surface electric boundary conditions, i.e. impermeable and permeable. It has been shown that the effects of the thickness and material constants of the piezoelectric layer on all the three parameters, i.e. G/G0, KIII/KIII0and KD/KD0were significant.
Jinxi Liu - One of the best experts on this subject based on the ideXlab platform.
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propagation of a mode iii Interfacial Crack in a piezoelectric piezomagnetic bi material
International Journal of Solids and Structures, 2012Co-Authors: Haosen Chen, Weiyi Wei, Jinxi Liu, Dai Ning FangAbstract:The transient response of a semi-infinite mode-III Interfacial Crack propagating between piezoelectric (PE) and piezomagnetic (PM) half spaces is investigated in this paper. The integral transform method together with the Wiener–Hopf and Cagniard–de Hoop techniques is used to solve the mixed boundary value problem under consideration. The existence of generalized Maerfeld–Tournois Interfacial wave is discussed and the solutions of the coupled fields are derived for four different cases of bulk shear wave velocity. The dynamic intensity factors of stress, electric displacement and magnetic induction as well as energy release rate (ERR) are obtained in explicit forms. The numerical results of the universal functions and dimensionless ERR for several different material combinations are presented and discussed in details. It is found that the Bleustein–Gulyaev (generalized Maerfeld–Tournois) waves dominate the dynamic characteristics of the Interfacial Crack propagation in PE–PM bi-material.
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interaction of a screw dislocation with a semi infinite Interfacial Crack in a magneto electro elastic bi material
Mechanics Research Communications, 2006Co-Authors: Rujiang Hao, Jinxi LiuAbstract:Abstract The interaction between a screw dislocation and a semi-infinite Interfacial Crack in a transversely isotropic magneto-electro-elastic bi-material is investigated. The dislocation line is perpendicular to the isotropic basal plane of the bi-material. The elastic and electromagnetic fields induced by the dislocation are obtained through the use of the complex variable method together with the superposition scheme. The stress, electric displacement and magnetic intensity factors as well as the image exerted on the dislocation are given explicitly. We find that the intensity factors are expressed in terms of the so-called effective materials and the radial component of the image force is only dependent on the elastic modulus of the material with the dislocation. As an illustrative example, the bi-material that consists of piezoelectric and piezomagnetic phases is analyzed.
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interaction of a screw dislocation with an Interfacial Crack in two dissimilar piezoelectric layers
Key Engineering Materials, 2004Co-Authors: Jinxi Liu, Ai Ping Liu, Z Q Jiang, A K SohAbstract:A screw dislocation interacting with a semi-infinite Interfacial Crack in two dissimilar piezoelectric layers is studied. The complex variable method and the conformal mapping technique are employed to obtain the solution of the problem. The stress and electric displacement intensity factors are given explicitly. We find that the stress and electric displacement intensity factors depend on the effective electro-elastic material constants. Numerical example shows that the influence of piezoelectric effect on the Crack tip shielding is significant.
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a screw dislocation interacting with an Interfacial Crack in two dissimilar piezoelectric media
Physica Status Solidi B-basic Solid State Physics, 2002Co-Authors: A K Soh, Jinxi Liu, Dai Ning FangAbstract:In this paper the interaction of a screw dislocation with a semi-infinite Interfacial Crack of two dissimilar piezoelectric materials is considered. The expressions for the electroelastic fields, intensity factors, and image force acting on a screw dislocation are given in explicit form in terms of complex functions. When one of two materials is purely elastic, the influence of electromechanical coupling on the stress intensity factor and the image force is analyzed in detail. In addition, the results obtained in the present paper can be reduced to several special cases that have been reported previously in the literature.
Jean Schmittbuhl - One of the best experts on this subject based on the ideXlab platform.
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mode iii Interfacial Crack propagation in heterogeneous media
Physical Review E, 2018Co-Authors: Camille Jestin, Olivier Lengline, Jean SchmittbuhlAbstract:We monitor optically the propagation of a slow Interfacial mode III Crack along a heterogeneous weak interface and compare it to mode I loading. Pinning and depinning of the front on local toughness asperities within the process zone are the main mechanisms for fracture roughening. Geometrical properties of the fracture fronts are derived in the framework of self-affine scale invariance and Family-Vicsek scaling. We characterize the small and large scale roughness exponents ζ_{-}=0.6 and ζ_{+}=0.35, the growth exponent at large scale β_{+}=0.58, and the power-law exponent of the local velocity distribution of the fracture fronts, η=2.55. All these analyzed properties are similar to those previously observed for mode I Interfacial fractures. We also observe a common power-law decay of the probability distribution function of avalanche area. We finally observe that amplitude of front fluctuations, local rupture velocity correlation in time, and larger size of events highlight more dynamically unstable behavior of mode III Crack ruptures.
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Interfacial Crack pinning effect of nonlocal interactions
Physical Review Letters, 1995Co-Authors: Jean Schmittbuhl, Stephane Roux, Jeanpierre Vilotte, Knut Jorgen MaloyAbstract:We propose a perturbative approach to describe the evolution of an Interfacial Crack between two elastic solids with quenched disorder. The driving force is the stress intensity factor along the Crack front. The latter is expressed as a function of the entire Crack geometry through a linear convolution with a long-ranged kernel using a first order approximation developed by Gao and Rice [J. Appl. Mech. 56, 828 (1989)]. The resulting problem is studied numerically and is shown to give rise to self-affine geometries with a roughness exponent $\ensuremath{\zeta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.35$ and a dynamic exponent $z\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.5$, very different from the corresponding exponents obtained with a local form of the driving force.
Minghao Zhao - One of the best experts on this subject based on the ideXlab platform.
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Displacement discontinuity analysis of a nonlinear Interfacial Crack in three-dimensional transversely isotropic magneto-electro-elastic bi-materials
Engineering Analysis With Boundary Elements, 2015Co-Authors: Yanfei Zhao, Minghao ZhaoAbstract:Abstract The displacement discontinuity method is introduced and extended to study the electric and magnetic nonlinear effect of an Interfacial Crack in three-dimensional magneto-electro-elastic bi-materials under combined loadings. Green’s functions due to uniformly distributed extended displacement discontinuities over a ring element are derived via the extended displacement discontinuity integro-differential equation method. The electric−magnetic polarization saturation model is adopted for the electric and magnetic nonlinearities at the vicinity of the Crack front where the perfect electric displacement and magnetic induction saturations are assumed. The final formulation is discretized as a system of linear equations and an iterative approach is introduced to solve the unknown sizes of the two saturation zones by requiring that the electric displacement and magnetic induction intensity factors vanish at ends of their corresponding zones. The effect of the electric and magnetic fields on the saturation zones and the influence of the saturation zones on the stress intensity factor are illustrated with numerical examples.
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analysis of an Interfacial Crack in a piezoelectric bi material via the extended green s functions and displacement discontinuity method
International Journal of Solids and Structures, 2014Co-Authors: Yanfei Zhao, Minghao Zhao, E Pan, Cuiying FanAbstract:Abstract Based on the extended Stroh formalism, we first derive the extended Green’s functions for an extended dislocation and displacement discontinuity located at the interface of a piezoelectric bi-material. These include Green’s functions of the extended dislocation, displacement discontinuities within a finite interval and the concentrated displacement discontinuities, all on the interface. The Green’s functions are then applied to obtain the integro-differential equation governing the Interfacial Crack. To eliminate the oscillating singularities associated with the delta function in the Green’s functions, we represent the delta function in terms of the Gaussian distribution function. In so doing, the integro-differential equation is reduced to a standard integral equation for the Interfacial Crack problem in piezoelectric bi-material with the extended displacement discontinuities being the unknowns. A simple numerical approach is also proposed to solve the integral equation for the displacement discontinuities, along with the asymptotic expressions of the extended intensity factors and J -integral in terms of the discontinuities near the Crack tip. In numerical examples, the effect of the Gaussian parameter on the numerical results is discussed, and the influence of different extended loadings on the Interfacial Crack behaviors is further investigated.
A J Rosakis - One of the best experts on this subject based on the ideXlab platform.
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shear dominated transonic Interfacial Crack growth in a bimaterial i experimental observations
Journal of The Mechanics and Physics of Solids, 1995Co-Authors: John Lambros, A J RosakisAbstract:In this work we describe a series of impact experiments performed on PMMA/4340 steel edge Cracked bimaterial plates. Specimens were impacted at 20 m s−1 in a one point bend configuration using a high speed gas gun. Dynamic Interfacial Crack propagation was observed using the optical method of Coherent Gradient Sensing and high speed photography. Very high Crack tip accelerations (108 m s−2) and very high Crack tip speeds (up to 1.5cRPMMA) were measured and are reported. Quantitative measurements show that in experiments in which the Crack tip speed entered the intersonic range for PMMA, the stress field surrounding the Crack tip was shear dominated. The observation of high shear around the Crack tip can also be explained using wave propagation arguments. It is found that the reason for attainment of intersonic (with respect to PMMA) Crack tip speeds is directly related to the large amounts of energy necessary to initiate the Crack tip under shear dominated conditions. A comparison with the theoretical results of Part II in this study is also made. There seems to be an unfavorable region of stable Crack propagation velocities in the intersonic regime. This region is cspmma < v < √2csPMMA. In all experiments performed, the propagating Crack accelerated quickly out of this region. In the few interferograms that do actually correspond to Crack propagation in this unfavorable velocity range, Crack face contact was observed. This observation is also in agreement with the findings of Part II of this investigation.
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shear dominated transonic Interfacial Crack growth in a bimaterial i ii asymptotic fields and favorable velocity regimes
Journal of The Mechanics and Physics of Solids, 1995Co-Authors: Cheng Liu, Yonggang Huang, A J RosakisAbstract:Motivated by experimental observations of transonic Crack tip speeds (Lambros and Rosakis, 1994c, J. Mech. Phys. Solids 43(2), 169–188), the problem of intersonic Interfacial Crack growth in an elastic-rigid bimaterial system is analysed. Following the analytical procedure employed in Liu et al. (1993, J. Mech. Phys. Solids 41, 1887–1954), the two-dimensional in-plane asymptotic deformation field surrounding the tip of a Crack propagating intersonically along an elastic-rigid bimaterial interface, is obtained. The theoretical results show that the near-tip stress field does not exhibit oscillations, while a stress singularity weaker than 0.5 still exists and is a function of the Crack tip speed. In addition, due to the intersonic nature of Crack growth, a singular line emanating from the moving Crack tip is present in the near-tip field. Across this line, stresses and particle velocities suffer infinite jumps. The theoretical analysis also shows that the near-tip deformation field is shear dominated. It is also shown that in the velocity range cs < v < √2cs, either Crack face contact or negative normal tractions ahead of the Crack tip exist. Visual evidence of such contact is reported in Part I of this study. These observations, together with additional experimental results of Part I, lead to the conclusion that Crack growth is favorable in the velocity regimes 0 < v < cs and √2cs < v < c1.