Papers by Keyword: Green's Function

Abstract: A theoretical analysis is followed to calculate the dynamic stress intensity factors (DSIFs) in transversely isotropic piezoelectric bi-materials, due to existence of a permeable interfacial crack, near the edge of a circular cavity. The model is subjected to dynamic incident anti-plane shearing (SH-wave) and the formulation based on Green's function method. Conjunction and crack-simulation techniques are applied to obtain DSIFs at the crack’s outer tip. Calculations are prepared based on FORTRAN language program. A comparison is accomplished between the present model and another model with a crack emerging from the cavity edge to calibrate the program. Calculating results showed the influences of the physical parameters, the structural geometry and the wave frequencies on the dimensionless DSIFs and how those affected the efficiency of piezoelectric devices and materials.

Abstract: In transversely isotropic piezoelectric bi-materials, a theoretical analysis is followed to calculate the dynamic stress intensity factors (DSIFs) due to existence of a permeable interfacial crack, near the edge of a circular cavity. The model is subjected to dynamic incident anti-plane shearing (SH-wave) and Green's function method is the base of formulation. Conjunction and crack-simulation techniques are applied to obtain DSIFs at the crack’s inner tip. Calculations are prepared based on FORTRAN language program. For calibration of program, a comparison is accomplished between the present model and another with a crack emerging from the cavity edge. Calculating results clarified the influences of the physical parameters, the structural geometry and the wave frequencies on the dimensionless DSIFs and how those affected the efficiency of piezoelectric devices and materials.

Abstract: The lithium ion battery, thanks to their high density and high power, became promotes element for hybrid and EV vehicles. After several recent researches, it has been proved that lithium ion batteries are currently confronts a problem of temperature rise during their operation discharge, which affects the batteries performance, efficiency and reduces the life of lithium ion battery. However, this work is set to access the three dimensional analytical modeling based on Greens Function technique to study the thermal behavior of lithium-ion battery during discharge with different discharge rates (0.3C, C/2,1C, 2C,) and strategies natural convection cooling on the surface of the battery is performed.

Abstract: In engineering composite materials, earthquake engineering and modern municipal construction, it can be found that there are shallow-buried cavity or inclusion structure near surface. When structure is impacted by dynamic load, scattering field will be produced because of the cavity or the inclusion, and it could cause dynamic stress concentration at the edge of the cavity or inclusion. In this paper, Green's Function is studied, which is the solution of displacement field for elastic semi-space with multiple shallow-buried cavities and inclusions while bearing anti-plane harmonic line source force at any point. In the complex plane, considering the symmetry of SH-wave scattering, the displacement field aroused by the anti-plane harmonic line source force and the scattering displacement field impacted by multiple cylindrical cavities and inclusions are constructed. Through applying the method of multi-polar coordinate system, the equations with unknown coefficients can be obtained by using the stress or displacement condition of the cylindrical cavities and inclusions in the radial direction. According to orthogonality condition for trigonometric function, these equations can be reduced to a series of algebraic equations. By solving these algebraic equations the value of the unknown coefficients can be obtained. So the total wave displacement field could be got. By using the expressions, an example is provided to show the effect of the change of relative location of the cylindrical cavities, inclusions and the location of the line source force.

Abstract: By combining the method of moment (MoM) and the method of network analysis, we analyze the microstrip filter circuits. First, we deduce and calculate the closed form multilayered Green’s function by using the discrete complex image method. Then, we apply the multilayered Green’s function into the method of moment (MoM) and by using the multi-port network theory, we get the networks parameters. At last, the numerical result proves the method’s accuracy and validity.

Abstract: This paper presents an accurate analytical method to obtain the rocking impedance function of a surface-supported strip foundation. The Green’s functions of the elastic half-space under concentrated or uniform loads with infinite length are derived and an elaborate integration method is used to calculate the multi-value improper integral. The interface between the foundation and the supporting medium is divided into a number of strip units. The rocking impedance function is solved by adding the moments in every strip, based on the fact that the vertical displacement of each unit can be uniquely determined by the rotation amplitude of the rigid foundation. Excellent convergence has been observed. Comparing the numerical results to those obtained by the thin layer method, good agreements are achieved. Finally, the effect of the Poisson’s ratio on the rocking impedance function of the strip foundation is discussed in detail.

Abstract: The methods of Green's function, complex function and multi-polar coordinates are applied here to report interaction of an elliptical inclusion and a crack in half-space under incident SH-waves. Based on the symmetry of SH-waves scattering, the "conformal mapping" technology was developed to construct a suitable Green's function, a fundamental solution to the displacement field for the elastic half space containing elliptical inclusion while bearing out-plane line source load at arbitrary point, for creating a beeline crack with arbitrary length at any position combined with crack-division technology. The displacement field and stress field were then deduced while the inclusion coexists with the crack Lastly, numerical examples are presented to discuss the dependence of dynamic stress concentration factor (DSCF) around the elastic inclusion on different parameters.

Abstract: Dynamic anti-plane behaviors are studied on two dissimilar piezoelectric media with an interfacial non-circular cavity subjected to time harmonic incident anti-plane shearing. Based on Greens function and conformal mapping method, the dynamic stress concentration factors at the edge of the non-circular cavity are obtained by applying the orthogonal function expansion technique. Numerical cases about two dissimilar piezoelectric media with an elliptic cavity are provided with different elliptic axial length ratio, different wave number and different piezoelectric characteristic parameter. The calculating results show that dynamic analyses are of importance at lower frequencies and larger piezoelectric characteristic parameters.

Abstract: Waves in superlattice (SL) contained inhomogeneities with anisotropic correlation properties are considered. The anisotropy of the correlation during the transition from 3D to 2D disorder is characterized by the parameter , where and are the correlation wave numbers along the axis of the SL and in the plane of the its layers, respectively ( and are the correlation radii). Dependencies of both the dynamic susceptibility and density of states at the continuous transition from the isotropic three-dimensional inhomogeneities () to the two-dimensional ones () have been obtained.

Abstract: The possibility of the Cooper instability in transition metal compounds has been established on the bases of an idea about a strong interaction in a unit cell. The phase diagram of the superconducting ordering depending on a number of holes (h_d) of the 3d-shells has been obtained. The non-phonon BCS constant has been calculated.