We present an exact analysis of axisymmetric bending of circular plates according to elasticity theory. On the basis of Hamiltonian state space approach, a rigorous solution of the problem is determined by means of separation of variables and symplectic eigenfunction expansion in a systematic way. The thickness effect on bending of circular plates and the applicability of the classical plate solutions for the problem are evaluated accordingly.

The paper is to solve the problem of the response of stratified half-space subjected to triangularly distributed time-harmonic loadings on an axial symmetric area in the stratified half-space. Since the distributed area can be very small, the solution can be employed to deal with the problems of elastodynamics using the fundamental solution method. The advantage of the presented solution over Green function is that no singularity will occur in the presented solution. Some numerical results are given and some conclusions have been made. The presented solution is very efficient in computation.

The present paper is concerned with an in-depth study of the effects of rotation, two-temperature parameter and voids on the magneto-thermoelastic interactions in a homogeneous, isotropic, generalized half-space with gravity field. The formulation is applied within the frame-work of two-temperature generalized thermoelasticity based on the hyperbolic heat conduction model with one relaxation time. Using normal mode analysis technique for the physical variables appearing in the governing equations, we get the analytical expressions for displacement components, stress, thermodynamic temperature, conductive temperature and change in volume fraction field. The general solution obtained is then applied to a specific problem of an infinite half-space having isothermal boundary subjected to mechanical load. Variations of the considered variables through the vertical distance are illustrated graphically.

A new type of steel-concrete composite beam with double-box cross-section is proposed in this paper. In order to investigate stress behaviors and deflection characteristics of such composite beam with wide flange considering the shear lag effect, theoretical analysis and experimental study are launched simultaneously. Based on the minimum potential energy principle, governing differential equations in view of the shear lag effect are deduced by energy variational method, and analytical solutions of it's stress and deflection under the effect of symmetrical loading are calculated. The preceding analyses show that relative error is less than 14.71%, with a good agreement, and farther show that this method of theoretical derivation, which is used for analyzing shear lag effect of composite beam with wide flange, has certain reference and guidance.

In this paper, the electro-elastic fields in a functionally gradient piezoelectric strip with an internal semi-infinite electrode are analyzed by using Fourier transform and Wiener-Hopf technique. The exact forms of asymptotic solutions and intensity factor and energy are obtained. The energy density criterion is proposed to study the fracture behavior near the electrode tip. The fracture initiation angle depends on the fracture resistance of the piezoelectric ceramic, bonding strength between piezoelectric and electrode, and the direction of least energy density factor S inside the piezoceramic.

The vibration control of smart structure is considered in this paper. Membrane SAR antenna structure with piezoelectric sensors and actuators is taken as an example. The dynamic model is build up based on vector form intrinsic finite element (VFIFE) method. The four nodes membrane element, sensor element and actuator element for VFIFE are presented. By decentralized control stratagem, the bending and torsional vibrations of the membrane SAR antenna can be decoupled on measurement and driving control. The fuzzy control and adaptive fuzzy control are applied to suppress the bending and torsional vibrations of the membrane SAR structure. In the numerical experiment section, form finding is first carried out, then vibration control simulations are studied. The results demonstrate that adaptive fuzzy control algorithm can suppress the vibrations more effectively than the fuzzy control algorithm.

In this paper, two formulations in explicit form to derive the fundamental solutions for two and three dimensional unsteady unbounded Stokes flows due to a mass source and a point force are presented, based on the vector calculus method and also the Hörmander’s method. The mathematical derivation process for the fundamental solutions is detailed. The steady fundamental solutions of Stokes equations can be obtained from the unsteady fundamental solutions by the integral process. As an application, we adopt fundamental solutions: an unsteady Stokeslet and an unsteady potential dipole to validate a simple case that a sphere translates in Stokes or low-Reynolds-number flow by using the singularity method instead by the traditional method which in general limits to the assumption of oscillating flow. It is concluded that this study is able to extend the unsteady Stokes flow theory to more general transient motions by making use of the fundamental solutions of the linearly unsteady Stokes equations.

In this study, a vortical stator assembly (VSA) was developed to improve the rotor performance, surrounding a drag-type, vertical-axis wind turbine (VAWT). A rotor with six half-tube blades was employed. The VSA consisted of a number of guide vanes, which were to guide the air tangentially into the VSA. The design was to generate a vortical flow inside the VSA, to reduce the negative torque of the returning rotor blade, and to increase the air speed into the rotor. Wind tunnel model tests were conducted to investigate how the VSAs affected rotor performance. Four VSAs were developed in this study, employing 4, 6, 8 and 12 guide vanes that were 24cm in width, and one 6-guide-vane VSA employing guide vane widths of 12, 18, 24 and 30cm. Results indicated that VSAs can substantially augment the rotor performance, depending on the number and length of guide vanes. The 6-guide-vane VSA produced the largest effect on the rotor performance, and the optimal VSA diameter was approximately 1.82 times the rotor diameter. At an air speed of 6m/s, the optimal VSA helps to increase the free-running rotational speed by 318%, the torque output by 200%, and the maximal power output by 910%.

In this study a novel approach for 3D modeling of cylindrical sample of hot mix asphalt (HMA) is presented. To this end, the cylindrical sample was divided into several slices and using a developed algorithm the processed images were extended to 3D volumetric objects to reconstruct the 3D microstructure of HMA. To evaluate the efficiency of the presented 3D model for prediction of mechanical behavior, HMA was regarded as a two-phase mixture; mastic phase and aggregate phase. The asphalt binder, filler, air voids and fine aggregates were considered as mastic with viscoelastic behavior and the aggregate was considered as an elastic material. Two models (Burger and generalized Kelvin) were studied for determining viscoelastic behavior of mastic. Finally, to verify the model using Finite Element Method (FEM) the behavior of the 3D model was simulated under different uniaxial compressive loads. A good agreement was observed between the simulated results and corresponding experimental data which indicates the efficiency of the proposed model to simulate three-dimensional asphalt.

The present paper is devoted to the investigation of steady MHD axi-symmetric flow between two infinite stretching disks with slip effects. Our attention lies in obtaining the similarity solutions of the governing partial differential equations. The transformed boundary value problem is solved analytically for a series solution using homotopy analysis method. The convergence of the obtained solution is established and fluid velocity and pressure are analyzed for various set of parameter values. The obtained results are valid for both moderate and large values of Reynolds number.

Maximum ellipsoidal magnitude of the droplet is an important basic parameter for calculating drag force, droplets axial-velocity and dispersed-phase pressure gradient in an annular-mist pipe flow. An analytical correlation to predict the maximum ellipsoidal magnitude of a low-viscosity droplet in a parallel gas stream based on energy conservation and volume conservation. Stagnant pressure distribution on droplet surface is revised from Flachsbart's formula. The proposed correlation has clear physical meaning and easy to use. The correlation captures the deformation mechanism with an average absolute percent error of 9.53%. The effect of stagnant pressure distribution on the proposed correlation's accuracy is discussed.

Heat convection of a microchannel gas flow with constant wall heat flux boundary condition is investigated numerically, considering viscous dissipation and axial conduction. The shear work due to the slipping fluid at the wall is incorporated in the analysis. An analytical solution for fully developed conditions is also derived. The effect of the shear work on heat transfer is quantified through a comparative analysis in both the entrance- and the fully developed- regions. The analysis shows that the shear work effect on heat transfer is considerable, and neglecting this term leads to an overestimation of the Nusselt number in gas heating and an underestimation in gas cooling. The over/under estimation of the Nusselt number is dependent on both the Knudsen number and the Brinkman number. The results presented also demonstrate the significance of the shear work in the developing flow region. It is shown that in the developing flow region the Nusselt number is less sensitive to viscous dissipation when the shear work is neglected. It can be concluded from this study that the shear work effect is significant and neglecting it can lead to considerable errors in microchannel flow heat transfer.

A new simulation method for solving fluid-structure two-way coupling problems has been developed. All the basic equations are numerically solved on a fixed Cartesian grid using a finite difference scheme. A new definition of velocity-vorticity formulation aids us to introduce an immersed boundary method that does not require a force term to impose the no-slip condition on the solid boundaries. The proposed method is easy to implement and apply for two-way fluid-structure interaction problems. The dynamics of a falling and rising circular cylinder in a quiescent fluid as well as the motion of a circular cylinder in a lid-driven cavity are considered to evaluate the capabilities of the presented method.

The evolution of asymmetric leeward-side flow structures around a moving sphere in the viscous flow is investigated. Simulations are carried out to investigate the variations of vortex-ring system at the moderate Reynolds number. A parallel laboratory experiment is undertaken in this study. The sphere travels a certain distance at constant speed and then stops to collide with a wall. The motion of moving sphere in fluid is described by the hybrid Cartesian immersed boundary method. Drag forces behind the moving sphere are extremely substantial as the solid body falls through viscous fluid for comprehending the formation of wake flow. The dynamic behavior consists of growth and breakup of the vortices which depend on two specific moderate Reynolds numbers. The onset of physical instability in the wake is obviously affected at the Reynolds number of 800. The generated vortex-ring system rolls upward to compact the primary vortex ring and interact with the secondary vortex. An asymmetric generation of the pairs of vortices is developed since the physical instability effect leads to shed in the wake with the increasing Reynolds number. The results from numerical simulations are also conducted to exhibit good comparison with those from the laboratory experiment.

A modified direct-forcing immersed-boundary (IB) pressure correction method is developed to simulate the flows of a falling ellipse. The pressure correct method is used to solve the solutions of the two dimensional Navier-Stokes equations and a direct-forcing IB method is used to handle the interaction between the flow and falling ellipse. For a fixed aspect ratio of an ellipse, the types of the behavior of the falling ellipse can be classified as three pure motions: Steady falling, fluttering, tumbling, and two transition motions: Chaos, transition between steady falling and fluttering. Based on two dimensionless parameters, Reynolds number and the dimensionless moment of inertia, a Reynolds number-inertia moment phase diagram is established. The behaviors and characters of five falling regimes are described in detailed.