Multilayered Inclusions Research Articles

Дослідження морфології багатошарових включень в сплавах системи Fe-C-Mn-Si-Ti-Al-N

Дослідження морфології багатошарових включень в сплавах системи Fe-C-Mn-Si-Ti-Al-N

INVESTIGATION OF THE INFLUENCE OF DEFORMATION AND HEAT TREATMENT OF STEEL ON THE PHASE COMPOSITION OF STEEL

In this paper, the phase composition of steel alloyed additionally with aluminum, nitrogen, titanium after deformation and heat treatment of steel is analyzed. The purpose of this work is to determine the phase composition of steel alloyed additionally with aluminum, nitrogen, titanium, the phase forming sequence during crystallization, morphology of multilayer inclusions. Research methods: Microstructural, X-ray microanalysis and X-ray diffraction analyses are used to determine the structural state of alloys. Research results: It is shown that during additional doping after crystallization the formation of multilayer inclusions, oxides, nitrides and carbonitrides occurs. It is testified that during the crystallization of steel the multiphase inclusions, in the center of which there is a metastable oxide (Al, Ti)2(O, N)3 surrounded by nitride (Ti, Fe) N, are formed from the melt. After further heating of the steel to a temperature of (1 533±10) K and hot plastic deformation with a degree of 50 % (HPD), the oxide (Al, Ti)2(O, N)3 is not revealed in the steel as a structural component. In the center of the multilayer inclusions the phase (Ti, Al) N surrounded by titanium nitride (Ti, Fe) N is observed. After heating and exposure at (1 123±10) K, individual inclusions of titanium nitride TiN, (Ti, Fe) N are observed.

Deformation and Strength Parameters of a Composite Structure with a Thin Multilayer Ribbon-like Inclusion.

Within the framework of the concept of deformable solid mechanics, an analytical-numerical method to the problem of determining the mechanical fields in the composite structures with interphase ribbon-like deformable multilayered inhomogeneities under combined force and dislocation loading has been proposed. Based on the general relations of linear elasticity theory, a mathematical model of thin multilayered inclusion of finite width is constructed. The possibility of nonperfect contact along a part of the interface between the inclusion and the matrix, and between the layers of inclusion where surface energy or sliding with dry friction occurs, is envisaged. Based on the application of the theory of functions of a complex variable and the jump function method, the stress-strain field in the vicinity of the inclusion during its interaction with the concentrated forces and screw dislocations was calculated. The values of generalized stress intensity factors for the asymptotics of stress-strain fields in the vicinity of the ends of thin inhomogeneities are calculated, using which the stress concentration and local strength of the structure can be calculated. Several effects have been identified which can be used in designing the structure of layers and operation modes of such composites. The proposed method has shown its effectiveness for solving a whole class of problems of deformation and fracture of bodies with thin deformable inclusions of finite length and can be used for mathematical modeling of the mechanical effects of thin FGM heterogeneities in composites.

Investigation of the Morphology and Electrical Properties of Graphene Used in the Development of Biosensors for Detection of Influenza Viruses.

In this study, we discuss the mechanisms behind changes in the conductivity, low-frequency noise, and surface morphology of biosensor chips based on graphene films on SiC substrates during the main stages of the creation of biosensors for detecting influenza viruses. The formation of phenylamine groups and a change in graphene nano-arrangement during functionalization causes an increase in defectiveness and conductivity. Functionalization leads to the formation of large hexagonal honeycomb-like defects up to 500 nm, the concentration of which is affected by the number of bilayer or multilayer inclusions in graphene. The chips fabricated allowed us to detect the influenza viruses in a concentration range of 10−16 g/mL to 10−10 g/mL in PBS (phosphate buffered saline). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that these defects are responsible for the inhomogeneous aggregation of antibodies and influenza viruses over the functionalized graphene surface. Non-uniform aggregation is responsible for a weak non-linear logarithmic dependence of the biosensor response versus the virus concentration in PBS. This feature of graphene nano-arrangement affects the reliability of detection of extremely low virus concentrations at the early stages of disease.

Coupling the BEM and analytical solutions for the numerical simulation of transient heat conduction in a heterogeneous solid medium

This paper simulates the three-dimensional transient heat diffusion conduction in a solid medium containing multi-layered cylindrical circular heterogeneities using a coupling formulation between the boundary element method (BEM) and analytical solutions. The analytical solutions are incorporated as Green's functions, thereby making the discretization of the interfaces of the multi-layered system unnecessary; this improves the efficiency of the algorithm. The coupling is enforced by imposing the continuity of temperature and heat fluxes at virtual interfaces created around each heterogeneity.The solution is first computed in the frequency domain, for a wide range of frequencies and axial wavenumbers, using complex frequencies to avoid aliasing phenomenon. Time series can then be obtained by means of a (fast) inverse Fourier transform.The accuracy, efficiency, and stability of the proposed algorithms are confirmed by comparing the results against reference solutions. The transient analysis of heat diffusion in a solid medium in the presence of multi-layered inclusions is used to illustrate the potential of the proposed coupling formulation.

Generalized Eshelby Problem in the Gradient Theory of Elasticity

A generalized Eshelby problem of arbitrary order in the gradient elasticity for a multilayer inclusions of spherical shape with a polynomial strain field at infinity is considered. For this problem we propose a constructive method of solution in a closed finite form, using generalized Papkovich–Neuber representation and the system of canonical potentials based on harmonic polynomials. We use also the Gauss theorem on the decomposition of an arbitrary homogeneous polynomials. The solutions of the generalized Eshelby problem are applied in the method of asymptotic homogenization of the gradient elasticity to accurately calculation of the effective characteristics of composite materials with scale effects.

Parallel Volume Integral Equation Method for Two-Dimensional Elastodynamic Analysis

The parallel volume integral equation method (PVIEM) is applied for the analysis of two-dimensional elastic wave scattering problems in an unbounded isotropic solid containing various types of multiple multilayered anisotropic inclusions. It should be noted that the volume integral equation method (VIEM) does not require the use of the Green’s function for the anisotropic inclusion — only the Green’s function for the unbounded isotropic matrix is needed. A detailed analysis of the SH wave scattering problem is presented for various types of multiple multilayered orthotropic inclusions. Numerical results are presented for the elastic fields at the interfaces for square and hexagonal packing arrays of various types of multilayered orthotropic inclusions in a broad frequency range of practical interest. Standard parallel programming was used to speed up computation in the VIEM. The PVIEM enables us to investigate the effects of single/multiple scattering, fiber packing type, fiber volume fraction, single/multiple layer(s), multilayer’s shapes and geometry, isotropy/anisotropy, and softness/hardness of various types of multiple multilayered anisotropic inclusions on displacements and stresses at the interfaces of the inclusions and far-field scattering patterns. Also, powerful capabilities of the PVIEM for the analysis of general two-dimensional multiple scattering problems are investigated.

All-angle negative refraction of flexural wave propagation on phononic thin plates with multilayer inclusions

This paper investigated all-angle negative refraction phenomenon of flexural wave propagating on phononic thin plates. The phononic thin plate consisted of a host plate and a periodic lattice of multilayer cylindrical inclusions. A general multipole method was firstly developed to calculate the dispersion curves of phononic thin plates. With the presented method, all-angle negative refraction effect had been founded in the first dispersion curve by selecting suitable materials for the host plate and multilayer inclusions. In order to verify these dispersion curves, observed bandgaps had then been checked by averaged displacement amplitude spectra of finite inclusion arrays using multiple scattering simulations. Finally, two flat lenses had been designed to focus elastic filed of point sources at the frequencies where all-angle negative refraction occurred. They demonstrated the maximum image resolution of a point source can overcome the Rayleigh diffraction limit.

Extending and lowering band gaps by multilayered locally resonant phononic crystals

Locally resonant phononic crystals (LRPCs) have band gaps with low frequencies and the size of the cell is much smaller than the wave lengths of the band gaps. This unique property makes them good candidates for vibration control. Considering that the band gaps of the LRPCs are determined by the single cell rather than the periodic arrangement, it is important to design the microstructure of the cell. In this paper, band structures and transmission spectra of two dimensional multilayered LRPCs are investigated by the finite element method (FEM). It is found that the band gaps of the LRPCs can be extended to several frequency ranges by periodically embedding multilayered coaxial inclusions (i.e., alternate shells of soft rubber and hard metal) into a matrix. Moreover, the frequency responses of the multilayered periodic structures with different number of cells are simulated. There are several sharp dips which refer to high attenuation efficiency in the transmission spectra of the periodic structures with multilayered inclusions. The increase in the number of cells is also found to enhance the attenuation efficiency. Meanwhile, the geometrical effects of the layers on the band structures are investigated. By carefully designing the size and number of the shells in the multilayered inclusions, the band gaps can be extended and lowered. These results are helpful for the applications of LRPCs in noise and vibration control.

Inclusion evolution after calcium addition in Ti-bearing Al-kill steel

In current article, experiments with different calcium addition were carried out in an Al2O3 crucible at 1873 K to investigate the variation of inclusion in Ti-bearing Al-kill Steel. It was found that calcium significantly influenced the morphology, composition distribution and size of oxide inclusions in Ti-bearing Al-kill Steel. Liquid oxide inclusions were modified promptly after calcium addition. Meanwhile, calcium could also modify solid titanium aluminate inclusions to spherical ones similarly, but there were a number of multilayer inclusions in molten steel at the initial stage. Different calcium treatment level should be adopted in different titanium content steel production process. As for the production practice, to achieve the full liquid inclusions in molten steel, the amount of calcium and titanium should be controlled simultaneously during the production process.

Numerical analysis of SH wave field calculations for various types of a multilayered anisotropic inclusion

The Parallel Volume Integral Equation Method (PVIEM) is applied for the analysis of elastic wave scattering problems in an unbounded isotropic solid containing various types of a multilayered anisotropic inclusion. It should be noted that this numerical method does not require the use of the Green׳s function for the multilayered anisotropic inclusion-only the Green׳s function for the unbounded isotropic matrix is needed. This method can also be applied to solve general elastodynamic problems involving arbitrary shape and number of inhomogeneous and/or multilayered anisotropic inclusions. A detailed analysis of the SH wave scattering is presented for various types of a multilayered orthotropic inclusion. Numerical results are presented for the displacement and stress fields at the interfaces of the multilayered inclusion in a broad frequency range. Parallel volume integral equation method as a pioneer of numerical analysis enables us to investigate the effects of single/multiple layer(s), multilayer׳s shape and geometry, isotropy/anisotropy, and softness/hardness of the multilayered anisotropic inclusion on displacements and stresses at the interfaces of the inclusion.

Dynamic stress concentration for multiple multilayered inclusions embedded in an elastic half-space subjected to SH-waves

The dynamic stress concentration factor (DSCF) is evaluated along the interfaces of multiple multilayered inclusions embedded in a half-space when subjected to a plane harmonic SH-wave. A weak form of Helmholtz equation is utilized to derive a non-hypersingular boundary integral equations to compute the stresses. Eliminating the need to rely on hypersingular integrals, greatly simplifies the procedure. The numerical results obtained by the proposed method, are validated against analytical solutions.Various contributing factors that can influence the DSCF are investigated, including multiple scattering, layering, stiffness of the adjacent inclusions, and impedance contrast of the layers. The DSCF is found to be highly prone to these changes, particularly with the soft materials. Therefore, accurate analysis of stresses requires models that consider multiple scattering and layering. The presented result could be used for predicting the seismic failure of pipes and underground tunnels and for estimating the stress failure in strong ground motion seismology due to subsurface irregularities.

Multiple Scattering Using Parallel Volume Integral Equation Method: Interaction of SH Waves with Multiple Multilayered Anisotropic Elliptical Inclusions

The parallel volume integral equation method (PVIEM) is applied for the analysis of elastic wave scattering problems in an unbounded isotropic solid containing multiple multilayered anisotropic elliptical inclusions. This recently developed numerical method does not require the use of Green’s function for the multilayered anisotropic inclusions; only Green’s function for the unbounded isotropic matrix is needed. This method can also be applied to solve general two- and three-dimensional elastodynamic problems involving inhomogeneous and/or multilayered anisotropic inclusions whose shape and number are arbitrary. A detailed analysis of the SH wave scattering is presented for multiple triple-layered orthotropic elliptical inclusions. Numerical results are presented for the displacement fields at the interfaces for square and hexagonal packing arrays of triple-layered elliptical inclusions in a broad frequency range of practical interest. It is necessary to use standard parallel programming, such as MPI (message passing interface), to speed up computation in the volume integral equation method (VIEM). Parallel volume integral equation method as a pioneer of numerical analysis enables us to investigate the effects of single/multiple scattering, fiber packing type, fiber volume fraction, single/multiple layer(s), multilayer’s shape and geometry, isotropy/anisotropy, and softness/hardness of the multiple multilayered anisotropic elliptical inclusions on displacements at the interfaces of the inclusions.

Molecular beam epitaxy of graphene on ultra-smooth nickel: growth mode and substrate interactions

Graphene is grown by molecular beam epitaxy using epitaxial Ni films on MgO(111) as substrates. Raman spectroscopy and scanning tunneling microscopy reveal the graphene films to have few crystalline defects. While the layers are ultra-smooth over large areas, we find that Ni surface features lead to local non-uniformly thick graphene inclusions. The influence of the Ni surface structure on the position and morphology of these inclusions strongly suggests that multilayer graphene on Ni forms at the interface of the first complete layer and metal substrate in a growth-from-below mechanism. The interplay between Ni surface features and graphene growth behavior may facilitate the production of films with spatially resolved multilayer inclusions through engineered substrate surface morphology.

Scattering of a plane harmonic SH wave by a rough multilayered inclusion of arbitrary shape

Steady-state scattering of a plane harmonic SH wave by a multilayered inclusion of arbitrary shape consisting of a general number of homogeneous isotropic layers, embedded within a half space, is investigated by using a direct boundary integral equation approach. The layer interfaces are assumed to be either smooth or periodically corrugated without any sharp corners being present. The peak corrugation amplitude is arbitrarily prescribed. The corresponding integral equations are derived in terms of the unknown boundary displacements and tractions. The integral equations are discretized using linear elements leading to a system of linear algebraic equations which are solved by using the standard Gauss elimination procedure.Testing of the numerical results is performed by comparing the surface response of a cavity with those available in the literature. The tests show excellent agreement between the two results for different frequencies and angles of incidence.The numerical results include surface response of multilayered inclusions and pipes. The inclusion layers are assumed to be either softer or stiffer from the half space. The pipe layers include both soft–stiff and stiff–soft combinations of the materials.The layered inclusion results demonstrate that for the soft materials the presence of layers may significantly change the surface response when compared to the corresponding homogeneous inclusion motion. For stiff layers this effect is greatly reduced. The same phenomenon has been observed for the inclusions with periodically corrugated interfaces as well.The surface response of a layered pipe is found to strongly depend upon the nature of the incident wave and the materials of the layers.

GS47 多層偏心円形介在物が存在する媒体に各種面外荷重が作用する問題の解析

GS47 多層偏心円形介在物が存在する媒体に各種面外荷重が作用する問題の解析

Analyses of isotropic piezoelectric materials with multilayered elliptical inclusion under out-of-plane shear loadings

In this paper, two-dimensional electroelastic analyses are performed for isotropic piezoelectric materials containing a multilayered elliptical inclusion under out-of-plane mechanical and electrical loads at infinity. General solutions are provided in terms of complex functions, and several numerical examples are shown by graphical representation.

Diffraction of electromagnetic waves on a shutter resistive periodic structure with multilayer periodic inclusions

An algorithm is suggested permitting us to consider the impact of magnetodielectric filling on the scatter-absorption properties of periodic diffraction lattices of the “shutter” type made with resistive materials. The paper gives dependencies of the power reflection factor on the wavelength for spatial modes at different values of permittivity of the dielectric filling.

Diffraction of plane waves by an echelette with multilayered dielectric inclusion

On the basis of the semi-inversion method we obtain rigorous solution for the problem of diffraction of H-polarized waves by an echelette placed in dielectric layers. Peculiarities of formation of the scattered field due to the presence of a dielectric inclusion are shown. The main attention is paid to the study of the frequency-dependent scattering and absorbing properties of the structure. Numerical results are given.

Polarizability and Effective Permittivity of Layered and Continuously Inhomogeneous Dielectric Ellipsoids

In this paper, the polarizabilities of partially and continuously inhomogeneous dielectric ellipsoids are analyzed. Multilayer inclusions where the boundaries between the layers are confocal ellipsoids, are solved in a static field. Transmission line analogy is applied, resulting in matrices with which the field components and the polarizability can be solved. In case of the continuous permittivity profile, a differential equation is derived for the scattered potential, and from the amplitude of this function, the polarizability results. The limitation in the continuous case is that the permittivity function of the ellipsoid depend only on one coordinate (ξ) in the ellipsoidal coordinate system. The theory is applied to calculating the microwave attenuation of melting hail at the frequency of 1 GHz, where the hydrometeors are modeled as two-layer ellipsoids.