On the determination of the voltage field in the eccentric tube, from an aging elasticplastic material

В работе в ананлитическом виде определяется распределение полей напряжений в эксцентрической трубе, находящейся под действием внутреннего давления. Материал трубы моделировался средой, обладающей наследственно стареющими упругопластическими свойствами. Решение задачи проводилось в рамках метода возмущений. За малый параметр бралась величина эксцентриситета. В качестве невозмущенного состояния принималось осесимметричное упругопластическое напряженное состояние трубы, определенное с учетом возраста и истории нагружения материала. В результате моделирования выведено уравнение для определения формы и размера границы раздела упругой и пластичесой зон в трубе с эксцентриситетом, а также получены аналитические выражения для компонент напряжений в каждой из областей деформирования. In this work, the distribution of stress fields in an eccentric pipe under the action of internal pressure is determined in an analytical form. The pipe material was modeled by a medium with hereditarily aging elastoplastic properties. The problem was solved within the framework of the perturbation method. The eccentricity value was taken as a small parameter. The unperturbed state was taken to be the axisymmetric elastoplastic stress state of the pipe, determined taking into account the age and loading history of the material. As a result of modeling, an equation was derived to determine the shape and size of the interface between the elastic and plastic zones in a pipe with eccentricity, and analytical expressions were obtained for the stress components in each of the deformation regions.

Heat Transfer Optimization in Laminar Flow of Non-Linear Viscoelastic Fluids in Asymmetric Straight Ducts With Inclusions

This paper presents the preliminary findings of an optimization study of transversal flow strength in tube cross-sections with arbitrary external contours and an internal inclusion. The eccentric tube contours are generated through a one-to-one mapping of a base circular cross-section. The working fluid obeys the non-linear modified Phan-Thien-Tanner (MPTT) constitutive model. The computation of the total transversal flow rate leads to the determination of effective cross-sections for heat transfer enhancement.

ECF Micropump-Integrated Micro Hand by MEMS Technology

On purpose to realize a novel flexible micro-hand for biological and medical applications, this paper presents a major step forward in this direction by directly integrating micropumps into eccentric tube type micro-fingers driven by the ECF (Electro-Conjugate Fluid) jet. ECF is a functional fluid which can generate the strong jet by applying high DC voltage between the electrodes. The ECF eccentric tube type micro-hand (ECF-ETMH) comprises three elastic PDMS micro-fingers with eccentric void and their corresponding MEMS-fabricated ECF micropumps. Because of the geometrical asymmetry created by an eccentric void in a cylindrical elastic body, this micro-finger acts bending motion upon the pressurization of the eccentric void by the ECF jet. Each ECF micropump has 41 pairs of a triangular prism and slit electrodes (TPSEs) that are designed to generate maximum pressures of 300kPa at the applied voltage of 3.5kV. We successfully fabricated eccentric tube type micro-fingers (ETMF) by high aspect ratio micromolding. Although we could not succeed in integrating the ECF micropumps and ETMFs due to the leakage, we experimentally proved the feasibility of this micro-hand system by investigating the characteristics of them separately.

Standing Gravity Waves in a Horizontal Circular Eccentric Annular Tank

Standing gravity waves in half-full horizontal cylindrical containers with eccentric tube are analyzed using the linear theory of water waves. The problem solution is obtained by the method of conformal coordinate transformation, leading to standard truncated matrix Eigen-value problem from which fluid motion characteristics (Eigen-frequencies and wave modes) are calculated. The effects of tube eccentricity and radius ratio upon the three lowest antisymmetric and symmetric sloshing frequencies and the associated hydrodynamic pressure mode shapes are examined. Also, convergence of the adopted approach with respect to the eccentricity condition, and radius ratio is discussed. Accuracy of the present analysis is checked by comparison with the known results of the limiting cases.

Liquid Sloshing in a Horizontal Circular Container with Eccentric Tube under External Excitation

Appropriate conformal mapping transformation in combination with the linear potential theory is employed to develop mathematical model for two-dimensional sloshing in horizontal circular cylindrical containers with overall eccentric hole. The tube-type tank is filled with inviscid incompressible fluid up to its half depth and subjected to lateral accelerations. A ramp-step excitation encountered in a road turning maneuver as well as real seismic event is used to simulate the lateral acceleration excitation. The resulting linear sets of ordinary differential equations are truncated and then solved numerically by employing Laplace transform technique followed by Durbin’s numerical inversion pattern. The effects of excitation input time, eccentricity, and radii ratio on the hydrodynamic responses and suppression of the induced destabilizing lateral forces are examined. Limiting cases are considered and good agreements with available analytic and numerical solutions as well as the simulations performed by using a commercial FEM software package are obtained.