A concurrent multiscale method of coupling atomistic and continuum models is presented in the two-dimensional system. The atomistic region is governed by molecular dynamics while the continuum region is represented by...A concurrent multiscale method of coupling atomistic and continuum models is presented in the two-dimensional system. The atomistic region is governed by molecular dynamics while the continuum region is represented by construct- ing the mass and stiffness matrix dependent on the coarsening of the grids, which ensures that they merge seamlessly. The low-pass phonon filter embedded in the handshaking region is utilized to effectively eliminate the spurious reflection of high-frequency phonons, while keeping the low-frequency phonons transparent. These schemes are demonstrated by numerically calculating the reflection and transmission coefficient, and by the further application of dynamic crack propa- gation subjected to mode-I tensile loading.展开更多
Description on dynamic behaviours of crack-tips is one of the important foundations to develop a reasonable dynamic fracture criterion. In order to describe the dynamic behaviours of the crack-tip in a material with l...Description on dynamic behaviours of crack-tips is one of the important foundations to develop a reasonable dynamic fracture criterion. In order to describe the dynamic behaviours of the crack-tip in a material with low viscosity-number, the displacement potential function is assumed as a mathematical expression with exponential singularity. The asymptotic linear differential equations determining plane crack-tip field are established based on the mechanical constitutive model for elastic-viscoplastic materials. According to the conditions of determining solutions for dynamic cracks of mode II, the crack-tip stress fields are numerically simulated based on the asymptotic linear differential equations. Results show the asymptotic linear equations can well describe the crack-tip fields of plane dynamic cracks in the elastic-viscoplastic material with low viscosity-number.展开更多
This paper firstly works out basic differential equations of piezoelectric materials expressed in terms of potential functions, which are introduced in the very beginning. These equations are primarily solved through ...This paper firstly works out basic differential equations of piezoelectric materials expressed in terms of potential functions, which are introduced in the very beginning. These equations are primarily solved through Laplace transformation, semiinfinite Fourier sine transformation and cosine transformation. Secondly, dual equations of dynamic cracks problem in 2D piezoelectric materials are established with the help of Fourier reverse transformation and the introduction of boundary conditions. Finally, according to the character of the Bessel function and by making full use of the Abel integral equation and its reverse transform, the dual equations are changed into the second type of Fredholm integral equations. The investigation indicates that the study approach taken is feasible and has potential to be an effective method to do research on issues of this kind.展开更多
Within the infinitesimal deformation and plastic incremental theory, an asymptotic solution of near tip fields is presented in this paper for mode Ⅰ steady dynamic crack growth in a power law incompressible ...Within the infinitesimal deformation and plastic incremental theory, an asymptotic solution of near tip fields is presented in this paper for mode Ⅰ steady dynamic crack growth in a power law incompressible elastic plastic solid under plane strain conditions. This solution shows that the near tip stresses and strains are fully continuous and bounded, and depend only on one free parameter that must be determined from the far field. 展开更多
In the investigation on fracture mechanics,the potential function was introduced, and the moving differential equation was constructed. By making Laplace and Fourier transformation as well as sine and cosine transform...In the investigation on fracture mechanics,the potential function was introduced, and the moving differential equation was constructed. By making Laplace and Fourier transformation as well as sine and cosine transformation to moving differential equations and various responses, the dual equation which is constructed from boundary conditions lastly was solved. This method of investigating dynamic crack has become a more systematic one that is used widely. Some problems are encountered when the dynamic crack is studied. After the large investigation on the problems, it is discovered that during the process of mathematic derivation, the method is short of precision, and the derived results in this method are accidental and have no credibility.A model for example is taken to explain the problems existing in initial deriving process of the integral_transformation method of dynamic crack.展开更多
基金supported by the National Natural Science Foundation of China(Grants Nos.11102191 and 11172279)the Development Foundation of Institute of Fluid Physics,Chinese Academy of Engineering Physics(Grant No.SFZ20120402)
文摘A concurrent multiscale method of coupling atomistic and continuum models is presented in the two-dimensional system. The atomistic region is governed by molecular dynamics while the continuum region is represented by construct- ing the mass and stiffness matrix dependent on the coarsening of the grids, which ensures that they merge seamlessly. The low-pass phonon filter embedded in the handshaking region is utilized to effectively eliminate the spurious reflection of high-frequency phonons, while keeping the low-frequency phonons transparent. These schemes are demonstrated by numerically calculating the reflection and transmission coefficient, and by the further application of dynamic crack propa- gation subjected to mode-I tensile loading.
基金supported by China Postdoctoral Science Foundation(No.20080430933)the Program of Doctor Foundation of Ministry of Education of China(No.20060217010).
文摘Description on dynamic behaviours of crack-tips is one of the important foundations to develop a reasonable dynamic fracture criterion. In order to describe the dynamic behaviours of the crack-tip in a material with low viscosity-number, the displacement potential function is assumed as a mathematical expression with exponential singularity. The asymptotic linear differential equations determining plane crack-tip field are established based on the mechanical constitutive model for elastic-viscoplastic materials. According to the conditions of determining solutions for dynamic cracks of mode II, the crack-tip stress fields are numerically simulated based on the asymptotic linear differential equations. Results show the asymptotic linear equations can well describe the crack-tip fields of plane dynamic cracks in the elastic-viscoplastic material with low viscosity-number.
文摘This paper firstly works out basic differential equations of piezoelectric materials expressed in terms of potential functions, which are introduced in the very beginning. These equations are primarily solved through Laplace transformation, semiinfinite Fourier sine transformation and cosine transformation. Secondly, dual equations of dynamic cracks problem in 2D piezoelectric materials are established with the help of Fourier reverse transformation and the introduction of boundary conditions. Finally, according to the character of the Bessel function and by making full use of the Abel integral equation and its reverse transform, the dual equations are changed into the second type of Fredholm integral equations. The investigation indicates that the study approach taken is feasible and has potential to be an effective method to do research on issues of this kind.
文摘Within the infinitesimal deformation and plastic incremental theory, an asymptotic solution of near tip fields is presented in this paper for mode Ⅰ steady dynamic crack growth in a power law incompressible elastic plastic solid under plane strain conditions. This solution shows that the near tip stresses and strains are fully continuous and bounded, and depend only on one free parameter that must be determined from the far field.
文摘In the investigation on fracture mechanics,the potential function was introduced, and the moving differential equation was constructed. By making Laplace and Fourier transformation as well as sine and cosine transformation to moving differential equations and various responses, the dual equation which is constructed from boundary conditions lastly was solved. This method of investigating dynamic crack has become a more systematic one that is used widely. Some problems are encountered when the dynamic crack is studied. After the large investigation on the problems, it is discovered that during the process of mathematic derivation, the method is short of precision, and the derived results in this method are accidental and have no credibility.A model for example is taken to explain the problems existing in initial deriving process of the integral_transformation method of dynamic crack.
