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This paper provides the transfer matrix method for the solution of multiple elliptic layers with different elastic properties. In the study, the medium is composed of an elliptic inclusion and many confocal elliptic layers. In the present study, the exterior layer is a finite confocal elliptic layer. Some derivations in the present study are similar to those in Chen (Acta Mech ). However, some derivations in the present study are quite different from those in Chen (Acta Mech ). Equations for evaluating the coefficients in the Laurent series for complex potentials are suggested, which are derived from the transfer matrix and the boundary condition. A numerical example for the case of an elliptic inclusion and two confocal elliptic layers is provided in this paper. [ABSTRACT FROM AUTHOR]

In this paper, an efficient method is presented for the geometrically nonlinear analysis of circulant structures. A structure is called regular if its model can be formed as the product of two subgraphs, and if one of the subgraphs is a cycle then it is termed circulant. In the present method, we deal with the eigensolution of circulant structures by simply finding the eigenvalues and eigenvectors of the blocks of the stiffness matrix rather than those of the entire structural matrix, leading to a considerable reduction in the computational time. The developed method utilizes concepts from product graphs and linear algebra for the nonlinear analysis of structures. Graph products are used to perform the eigensolution of circulant structures through those of its constituting subgraphs. Here, using the existing numerical methods, nonlinear static and dynamic analyses can be performed. In the presented method instead of solving the characteristic equation in each iteration of each step, the eigensolution of the structure is obtained using the eigensolution of the primary structure (the structure of the first iteration of the first step) together with some simple mathematical operations. In the present method instead of heavy matrix operations such as inverting a matrix and solution of the corresponding equations, one needs only to perform simple matrix multiplications and additions. The advantage of the presented method becomes more apparent when it is applied to the nonlinear analysis of a structure, where analysis should be performed many times. [ABSTRACT FROM AUTHOR]

A description of brick/block masonry by continua equivalent to discrete systems made of blocks of different geometry and texture is proposed in this paper. Here, the reasons for the selection of a micropolar continuum with respect to the classical continuum are discussed. As recent research in various micromorphic multifield formulations shows, the problem of the choice of the most appropriate continuum to model masonry mechanical behavior is still open, and the advantages of non-classical continuum modeling are not yet completely ascertained. Earlier analyses performed on masonry panels in the presence of load and geometrical singularities pointed out the significant role of the additional degree of freedom of the micropolar continuum (microrotation) and of its gradient. The present study aims to expand the investigation into the consequences of changes in blocks' shape, size and arrangement on the response of block masonry panels under shear forces. This analysis points out the greater effectiveness of micropolar models in capturing the gross structural response of masonry, with respect to the classical modeling. The cases analyzed herein show that apart from the very peculiar case of orthotetragonal symmetry, not only the gradient of microrotation but also the relative rotation between the local rigid rotation and the microrotation, to which relevant non-symmetric strains correspond, are predominant in the majority of the performed numerical tests. Models lacking in these strain measures are therefore inappropriate. The results obtained, ascertained by analyses performed on discrete block assemblies, point out that the micropolar continuum provides a proper description of the masonry behavior. Moreover, the differences between micropolar and classical models remain when the internal lengths vanish. [ABSTRACT FROM AUTHOR]

This paper presents a numerical method to model a general system containing cracks and voids in an infinite elastic plate under remote cyclic loads. By extending Bueckner's principle suited for a crack to a general system containing cracks and voids, the original problem is divided into a homogeneous problem (the one without cracks and voids) subjected to remote loads and a void-crack problem in an unloaded body with applied tractions on the surfaces of cracks and voids. Thus, the results in terms of the stress intensity factors can be calculated by considering the latter problem, which is analyzed easily by using the hybrid displacement discontinuity method (a boundary element method). Further, a fatigue growth technique of a mixed-mode crack is combined with the numerical approach to simulating a void-crack interaction problem under cyclic loads. Test examples are included to illustrate that the numerical method is very simple and effective for analyzing a void-crack interaction problem. [ABSTRACT FROM AUTHOR]

This paper analyses the thermal and roughness effects on different characteristics of finite rough tilted pad slider bearings. The roughness is assumed to be stochastic, Gaussian randomly distributed. Density and viscosity are assumed to be temperature dependent. In this study, two models of one-dimensional roughness, longitudinal and transverse, are considered. The irregular domain due to roughness is mapped to a regular domain so that the numerical method can be easily applied. The modified Reynolds equation, momentum equation, continuity equation and energy equation are coupled and solved using the finite difference method to yield various bearing characteristics. It is observed that for nonparallel slider bearing the load carrying capacity due to the combined effect is less than the load capacity due to the roughness effect for both longitudinal and transverse roughness models. However, in case of a parallel pad slider bearing, the reverse is true, though the load capacity is not significant. It is also observed that the load carrying capacity due to the combined effect is larger than the load carrying capacity due to the thermal effect for both roughness models. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the system parameters on the flutter of a curved skin panel forced by a supersonic/hypersonic unsteady flow is numerically investigated. The aeroelastic model investigated includes the third-order piston theory aerodynamics for modeling the flow-induced forces and the Von Kármán non-linear strain-displacement relation in conjunction with the Kirchhoff plate hypothesis for the panel structural modeling. Structural non-linearities are considered and are due to the non-linear coupling between out-of-plane bending and in-plane stretching. The effects of thermal degradation and Kelvin's model of structural damping independent on time and temperature are also considered. The aero-thermo-elastic governing equations are developed from the geometrically imperfect non-linear theory of infinitely long two-dimensional curved panels. Computational analysis and discussion of the finding along with pertinent conclusions are presented. [ABSTRACT FROM AUTHOR]

This paper addresses numerical modeling of historical brick masonry subjected to in-plane loads. Based on experimentally determined material parameters for the masonry constituents brick and mortar numerical simulations of masonry specimens under various loading conditions are performed. These simulations aim at calibrating and validating parameter sets for historical brick masonry on the meso-scale. For computations on a larger scale, a macro-model in the framework of multi-surface plasticity theory is implemented in a finite element program, which captures the fundamental failure modes of in-plane loaded masonry. Material parameters for the macro-model are derived in a numerical homogenization procedure yielding the transition from the meso-scale to the macro-scale. Results from comparative simulations on discrete and homogenized models show both efficiency and limitations of the proposed methodology. [ABSTRACT FROM AUTHOR]

In this paper we describe a new model consisting of N articulated rigid bodies with open chain structure, that move in the combined gravitational field of two mutually attracting massive centers. We derive the general equations of motion of the chain and we study the conditions for the planar motion of the individual centers of mass of the links. [ABSTRACT FROM AUTHOR]

The present paper deals with a general thermodynamic framework for the modelling of temperature and rate dependent deformation behavior of anisotropically damaged elastic-plastic materials subjected to impact loadings. Based on the concepts of continuum damage mechanics, rate-dependent constitutive equations are derived from the first and second law of thermodynamics which are only based on a limited number of material parameters. Identification of the constitutive parameters is discussed and the applicability of the present continuum damage approach is demonstrated by numerical simulations of low and high strain rate tension tests. The evolution of different data is studied and compared with available experimental results. [ABSTRACT FROM AUTHOR]

The interaction of a buoyancy induced mixed convection flow and a free stream impinging at some angle of incidence on a vertical flat plate with a prescribed surface heat flux is studied in this paper. The similarity equations are numerically solved for some values of the governing parameters. It is found that the buoyancy force and non-orthogonal mechanisms act to either reinforce or oppose one another. The stagnation point (separation point) is shifted at the left or at the right of the origin and it depends upon the balance between obliqueness and thermal effects. [ABSTRACT FROM AUTHOR]

The paper deals with the prediction of coupled sway-roll-yaw motions of a ship with constant forward speed, subject to regular wave force. The governing equations derived in time domain after balancing the hydrodynamic and exciting forces are solved analytically while considering the motion variables, wave frequency and external force are complex quantities. Numerical experiments were carried out for a Panamax container ship under the action of a sinusoidal wave of periodicity 11.2 sec with the variations of speed and wave height. The effect of various parameters on motion responses and system stability is investigated. [ABSTRACT FROM AUTHOR]

This paper is devoted to the numerical study of axisymmetric rotating flow in enclosed cylinders with aspect ratios R (diameter divided by height) equal to 0.25, 0.33, 0.5, 1, 2, 3 and 4. The steady motion of the liquid is caused by the action of a low-frequency, low-induction rotating magnetic field with magnetic Taylor numbers lying in the range from 0.0025 · Ta cr to 0.9 · Ta cr , where Ta cr refers to the critical magnetic Taylor number. We found that the ratio between global meridional to global azimuthal flow velocity passes a distinct maximum which depends on the aspect ratio. It marks the transition from the viscous to the inertial regime. Their characteristic features are examined by analysis of the angular velocity and the torques exerted by the boundaries, in dependence on Ta and the aspect ratio. [ABSTRACT FROM AUTHOR]

In real systems there is always a certain amount of slip, which, however, is hard to detect experimentally because of the required space resolution. In this paper, we analyze the effect of slip boundary conditions on the dynamics of fluids in porous media by studying the flow of a Newtonian and non-Newtonian Maxwellian fluid in an axisymmetric cylindrical tube (pore), in which the flow is induced by traveling transversal waves on the tube wall. Like in peristaltic pumping, the traveling transversal waves induce a net flow of the liquid inside the pore. The viscosity as well as the compressibility of the liquid is taken into account. This problem has numerous applications in various branches of science, including stimulation of fluid flow in porous media under the effect of elastic waves and studies of blood flow dynamics in living creatures. The Navier-Stokes equations for an axisymmetric cylindrical pore are solved by means of a perturbation analysis, in which the ratio of the wave amplitude to the radius of the pore is small parameter. In the second order approximation, a net flow induced by the traveling wave is calculated for various values of the compressibility of the liquid, relaxation time and Knudsen number. The calculations disclose that the compressibility of the liquid, Knudsen number of slip flow and non-Newtonian effects in presence of peristaltic transport have a strong influence of the net flow rate. The effects of all parameters of the problem are numerically discussed and graphically explained. [ABSTRACT FROM AUTHOR]

A numerical analysis of a rigid rotor supported by relatively short externally pressurized porous gas journal bearings is presented for nonlinear dynamic behavior and bifurcation. The compressible Reynolds' equation is solved by the finite differences method, and the successive over relaxation method and a time-dependent mathematical model for porous gas journal bearings are studied. A comparison of the results for the system state trajectory, Poincaré maps, power spectra, and bifurcation diagrams is made, and the dynamic behavior of the rotor center in the horizontal and vertical directions under different operating conditions is analyzed. The analysis shows the existence of a complex dynamic behavior comprising periodic and quasi-periodic response of the rotor center. This paper shows how the dynamic behavior of this type of system varies with changes in rotor mass and bearing number. [ABSTRACT FROM AUTHOR]