Eccentric Inclusion Research Articles

Investigation of the effect of tool probe profile on reinforced particles distribution using experimental and CEL approaches

In this study, to explore the dispersion of particle reinforcement in the base metal, aluminum-6061/SiC composites were made utilizing friction stir processing (FSP) tools with various probe profiles such as cylindrical, triflate, square, triangular, and hexagonal. A light microscope was used to examine the dispersion of SiC particles in the composite substrate. Then the mechanical properties of the composite were investigated using hardness and tensile tests. In addition, the coupled Eulerian-Lagrangian (CEL) approach is used to model the process and investigate particle dispersion further. The workpiece is modeled employing Eulerian formulation, whereas the tool is described using Lagrangian formulation. The model forecasts temperature and strain variations in composites made with various probe profiles. The result showed that the cylindrical pin could not spread particles in the base alloy, indicating that it was not viable for composite manufacture. Flat-surfaced tools, such as square and triangle probe profiles, have dispersed particles better in aluminum. The findings revealed that the inclusion of eccentricity and pulse creation in these tools enhanced particle dispersion. Hexagonal and triflate probes offer the highest performance in terms of particle dispersion in the base metal. As the number of smooth tool probe surfaces rises from triangular to hexagonal, the hardness distribution becomes more uniform, and the amount of hardness in the composite increases.

Elucidating the mechanism governing cell rotation under DEP using the volumetric polarization and integration method.

Cell rotation can be achieved by utilizing rotating electric fields through which torques are generated due to phase difference between the dipole moment of cells and the external electric field. While reports of cell rotation under non-rotating electrical fields, such as dielectrophoresis (DEP), are abound, the underlying mechanism is not fully understood. Because of this, contradicting arguments remain regarding if a single cell can rotate under conventional DEP. What's more, the current prevailing DEP theory is not adequate for identifying the cause for such disagreements. In this work we applied our recently developed Volumetric Polarization and Integration (VPI) method to investigate the possible causes for cell rotation under conventional DEP. Three-dimensional (3D) computer models dealing with a cell in a DEP environment were developed to quantify the force and torque imparted on the cell by the external DEP field using COMSOL Multiphysics software. Modeling results suggest that eccentric inclusions with low conductivity inside the cell will generate torques (either in clockwise or counter-clockwise directions) sufficient to cause cell rotation under DEP. For validation of modeling predictions, experiments with rat adipose stem cells containing large lipid droplets were conducted. Good agreement between our modeling and experimental results suggests that the VPI method is powerful in elucidating the underlying mechanisms governing the complicated DEP phenomena.

Generalized complex variable boundary integral equation for stress fields and torsional rigidity in torsion problems

Theory of complex variables is a very powerful mathematical technique for solving two-dimensional problems satisfying the Laplace equation. On the basis of the conventional Cauchy integral formula, the conventional complex variable boundary integral equation (CVBIE) can be constructed. The limitation is that the conventional CVBIE is only suitable for holomorphic (analytic) functions, however. To solve for a complex-valued harmonic-function pair without satisfying the Cauchy–Riemann equations, we propose a new boundary element method (BEM) based on the general Cauchy integral formula. The general Cauchy integral formula is derived by using the Borel–Pompeiu formula. The difference between the present CVBIE and the conventional CVBIE is that the former one has two boundary integrals instead of only one boundary integral in the latter one. When the unknown field is a holomorphic function, the present CVBIE can be reduced to the conventional CVBIE. Therefore, the conventional Cauchy integral formula can be viewed as a special case applicable to a holomorphic function. To examine the present CVBIE, we consider several torsion problems in this paper since the two shear stress fields satisfy the Laplace equation but do not satisfy the Cauchy–Riemann equations. Using the present CVBIE, we can directly solve the stress fields and the torsional rigidity simultaneously. Finally, several examples, including a circular bar containing an eccentric inclusion (with dissimilar materials) or hole, a circular bar, elliptical bar, equilateral triangular bar, rectangular bar, asteroid bar and circular bar with keyway, were demonstrated to check the validity of the present method.

Impacts of age-dependent tree sensitivity and dating approaches on dendrogeomorphic time series of landslides

Different approaches and thresholds have been utilized in the past to date landslides with growth ring series of disturbed trees. Past work was mostly based on conifer species because of their well-defined ring boundaries and the easy identification of compression wood after stem tilting. More recently, work has been expanded to include broad-leaved trees, which are thought to produce less and less evident reactions after landsliding. This contribution reviews recent progress made in dendrogeomorphic landslide analysis and introduces a new approach in which landslides are dated via ring eccentricity formed after tilting. We compare results of this new and the more conventional approaches. In addition, the paper also addresses tree sensitivity to landslide disturbance as a function of tree age and trunk diameter using 119 common beech (Fagus sylvatica L.) and 39 Crimean pine (Pinus nigra ssp. pallasiana) trees growing on two landslide bodies. The landslide events reconstructed with the classical approach (reaction wood) also appear as events in the eccentricity analysis, but the inclusion of eccentricity clearly allowed for more (162%) landslides to be detected in the tree-ring series. With respect to tree sensitivity, conifers and broad-leaved trees show the strongest reactions to landslides at ages comprised between 40 and 60years, with a second phase of increased sensitivity in P. nigra at ages of ca. 120–130years. These phases of highest sensitivities correspond with trunk diameters at breast height of 6–8 and 18–22cm, respectively (P. nigra). This study thus calls for the inclusion of eccentricity analyses in future landslide reconstructions as well as for the selection of trees belonging to different age and diameter classes to allow for a well-balanced and more complete reconstruction of past events.

HUYGENS PRINCIPLE BASED IMAGING OF MULTILAYERED OBJECTS WITH INCLUSIONS

The application of a recently introduced microwave imaging technique based on the Huygens principle (HP), has been extended to multilayered objects with inclusions in this paper. The methodology of HP permits the capture of contrast such that difierent material properties within the region of interest can be discriminated in the flnal image, and its simplicity removes the need to solve inverse problems when forward propagating the waves. Therefore the procedure can identify and localize signiflcant scatterers inside a multilayered volume, without having apriori knowledge on the dielectric properties of the target object. Additionally, an analytically-based approach for analyzing UltraWide Bandwidth (UWB) body propagation is presented, where the body is modeled as a 3-layer stratifled cylinder with an eccentric inclusion. Validation of the technique through both simulations and measurements on multilayered cylindrical objects with inclusions has been performed.

An approach for exploring the dynamical behaviour of inhomogeneous structural inclusions under consideration of epistemic uncertainty

PurposeThe purpose of this paper is to analyze the wave scattering behaviour of an inhomogeneous and eccentric inclusion in a homogeneous matrix material. Another purpose is to evaluate the influence of epistemic uncertainty on the wave scattering behaviour, particularly on the lack of knowledge about this eccentricity. This task calls for a multidisciplinary model.Design/methodology/approachThe inclusion is modelled as a multi‐layered obstacle, with all layers being eccentric with respect to each other. The material behaviour of the embedding matrix is linear elastic and isotropic. In a multidisciplinary approach, the interaction of the inhomogeneous inclusion and the embedding matrix with respect to an incoming shear wave of arbitrary shape is solved analytically. The purely analytical solution process takes place in the frequency‐domain. Due to the lack of knowledge about the eccentric configuration of the matrix inclusion and its influence on the total wave field inside the matrix material, the mechanical model is coupled with fuzzy set theory for modelling this non‐stochastic uncertainty.FindingsAn analytical model for describing the wave scattering behaviour of an elastic matrix inclusion with eccentric set‐up is found and intimately connected with the framework of fuzzy set theory. Hence it is shown that the treatment of epistemic uncertainty with the derived analytical model is possible and fruitful. Additionally, it is shown that eccentric configurations lead to highly increased amplitudes with respect to the reference case of a concentric or even homogenous set‐up of the inclusion.Originality/valueThe value of this contribution is in the analytical model, which allows one to predict the wave scattering behaviour of eccentric configurations of multi‐layered fibres including the surrounding interphase, and its coupling with fuzzy set theory to cope with the epistemic uncertainty inherent in the geometric set‐up of the matrix inclusion.

On the scattering behaviour of elastic waves in textile reinforced concrete

An exact analytical solution for the scattering of antiplane elastic waves by a layered elastic eccentric inclusion is derived beginning from the solution of the wave equation in elliptic coordinates. The solution and its degenerate cases are compared with other models, e.g. the scattering due to concentric circular scatterers. The effects of the geometrical properties of the interphase are studied. Hereby the focus lies on geometric parameters which fit the needs of Textile Reinforced Concrete (TRC). The calculations are performed for material properties as they occur with TRC. The numerical results show an enormous influence of eccentricities within TRC to its wave scattering behaviour.

Radiation force of a sphere with an eccentric inclusion illuminated by a laser beam

Based on the theory of the scattering of an eccentric sphere arbitrarily illuminated by a shaped beam which is recently presented by us, and according to generalized Lorenz-Mie theory （GLMT）, we derived the series expressions of radiation forces exerted by the incident beam on an eccentric sphere by using the conservation law of electromagnetic momentum and the Mexwell-Tensor. As an example, numerical results of radiation force of absorbing eccentric spheres for off-axis incidence of Gaussian beam are given, along with a discussion about the influence of the beam-waist radius, relative complex refractive index, relative size and location of the inclusion on the forces.

Electromagnetic stress on resonant light scattering by a cylinder with an eccentric inclusion

We analyze the resonant scattering of light by a dielectric cylinder with an eccentric cylindrical metallic inclusion. We make efforts to understand the behavior of the electromagnetic (EM) fields and forces inside the dielectric shell as some parameters of the theory vary. To this end, we developed an algorithm for resonant mode calculation and we use an internal multi-reflection ray theory (Debye expansion method) to interpret the resonant and non-resonant contributions to electromagnetic fields as well as the Maxwell stress tensor.

The Rotor Dynamic Coefficients of Eccentric Mechanical Face Seals

Abstract The Reynolds equation is extended to include the effects of radial deflection in a seal with two flexibly mounted rotors. The resulting pressures are used to obtain the forces and moments introduced in the axial and angular modes by the inclusion of eccentricity in the analysis. The rotor dynamic coefficients relating the forces and moments in these modes to the axial and angular deflection are shown to be the same as those presented in the literature for the concentric case. Additional coefficients are obtained to express the dependence of these forces and moments upon the radial deflections and velocities. The axial force is shown to be decoupled from both the angular and radial modes, but the angular and radial modes are coupled to one another by the dependence of the tilting moments upon the radial deflections. The shear stresses acting upon the element faces are derived and used to obtain the radial forces acting upon the rotors. These forces are used to obtain rotor dynamic coefficients for the two radial degrees of freedom of each rotor. The additional rotor dynamic coefficients can be used to obtain the additional equations of motion necessary to include the radial degrees of freedom in the dynamic analysis. These coefficients introduce additional coupling between the angular and radial degrees of freedom, but the axial degrees of freedom remain decoupled.

Scattering and absorption cross sections of compounded spheres III Spheres containing arbitrarily located spherical inhomogeneities

The theory of light scattering by spheres possessing one or more spherical inhomogeneities is developed. The inhomogeneities, or subspheres, are of uniform but otherwise arbitrary composition and are restricted in size and number by only the volume of the host. Numerical results for single inclusions are considered in regard to questions that have arisen in the course of recent experimental research on morphology-dependent resonances in droplets. The modification of the light-absorbing properties of carbon by its entrainment in droplets is also studied. The predicted absorption by mass of soot particles in cloud droplets tends to be higher when the particles are centered in the droplets than when the more realistic eccentric inclusion model is used. Absorption by carbon that is internally mixed in sulfate hazes is more sensitive to the relative sizes of the sulfate and carbon particles, but absorption by eccentrically included grains tends not to differ greatly from that predicted by concentric models.

Indirect mode-matching solution to scattering from a dielectric sphere with an eccentric inclusion

The analytical formulation of electromagnetic wave scattering from an eccentrically stratified dielectric sphere is greatly simplified through the indirect mode-matching technique. The resulting exact solution is the most compact available and hence the least prone to analytical or numerical errors. After some checks we present a comparison between our solution and two previous solutions that were obtained through direct mode matching. Our numerical investigation is focused on an acrylic sphere with an eccentric cavity. All four elements of the scattering matrix are available, and specific information about the possibility of detecting the scatterer’s internal asymmetry is given.

Optical properties of spheres containing a spherical eccentric inclusion

The formalism presented a few years ago by Fikioris and Uzunoglu [ J. Opt. Soc. Am.69, 1359 ( 1979)] to describe the electromagnetic scattering by homogeneous spheres containing an eccentric spherical inclusion is reformulated. The resulting approach is an extension of our previous formalism [ Aerosol Sci. Technol.3, 27 ( 1984)] designed to deal with the dependent scattering by aggregated spheres and is put in a form readily extensible to the case of spheres containing more than one inclusion. A comparison of our results with those of Fikioris and Uzunoglu is made, and the differences are explained in terms of the approximations that they used. Specific results for dielectric spheres containing either a metallic inclusion or a dielectric inclusion with parameters quite incompatible with the approximation scheme of Fikioris and Uzunoglu are also presented. These scatterers have a response that depends on the direction of incidence and, in general, also on the polarization, thus making them distinguishable from spheres with a centered inclusion as well as from homogeneous spheres.

Extinction coefficient of a dispersion of non-absorbingspheres containing highly-absorbing eccentric inclusions

A general formalism devised to describe the scattering properties of homogeneousspheres containing several spherical inclusions is presented. The results for the scattering amplitude of non-absorbing spheres containing a single metallic inclusion as well as for the extinction coefficient of a low-density dispersion of these objects are discussed.