Search results

The paper deals with the investigation of linear buckling and free vibration behavior of layered and multiphase magneto‐electro‐elastic (MEE) beam under thermal environment. The constitutive equations of magneto‐electro‐elastic materials are used to derive finite element equations involving the coupling between mechanical, electrical and magnetic fields. The finite element model has been verified with the commercial finite element package ANSYS. The influence of magneto electric coupling on critical buckling temperature is investigated between layered and multiphase magneto‐electro‐elastic beam. Furthermore, the influence of temperature rise on natural frequencies of magneto‐electro‐elastic beam with layered and different volume fraction is presented.

A thermal analogy method for the static and dynamic analysis of an electrostrictive beam by incorporating the nonlinear characteristics of the electrostrictive materials is described in this paper. The analogy between thermo elastic finite element formulation and the electrostrictive material finite element formulation developed in this paper was explored. Based on this analogy, the voltage actuation of the electrostrictive beam can be simulated accurately using the conventional elastic finite element model with the thermal actuation. The finite element model includes the quadratic dependence of strain with electric field, valid at constant temperature and mechanical prestress, and excludes hysteresis.

In this paper, a semi‐analytical finite element formulation is presented to study the magnetoelectric (ME) effect for a multilayered and multiphase magneto‐electro‐elastic (MEE) cylinder under various boundary conditions. Numerical studies are done to evaluate the ME coefficient for different thickness ratio of piezoelectric phase in the multilayered composite. Studies are also done for the evaluation of ME coefficient for different volume fractions of piezoelectric phase in the multiphase composite. Ansys 8.1 is used to validate the present formulation using thermal analogy concept.

This paper aims to present harmonic response of magneto‐electro‐elastic cylinder by quasi‐static and fully dynamic electromagnetic theories. The quasi‐static assumption uses magnetic scalar potential whereas magnetic vector potential is employed in a fully dynamic model.

The electric field induced by time varying magnetic field is non‐conservative and can be described by electric scalar potential and magnetic vector potentials.

The magnitude of vector potential is dominant in axial and circumferential direction whereas the magnetic flux density is significant in radial direction. Magnetic scalar potential approach evaluates only the radial component of magnetic flux density and electric field intensity is reasonably the same as that of the magnetic vector potential approach.

Semi‐analytical finite element method is used in this paper and the vector potential is formulated in cylindrical coordinates.

The purpose of the paper is to investigate the linear thermal buckling and vibration analysis of layered and multiphase magneto‐electro‐elastic (MEE) cylinders made of piezoelectric/piezomagnetic materials using finite element method.

The constitutive equations of MEE materials are used to derive the finite element equations involving the coupling between mechanical, electrical, magnetic and thermal fields. The present study is limited to clamped‐clamped boundary conditions. The linear thermal buckling is carried out for an axisymmetric cylinder operating in a steady state axisymmetric uniform temperature rise. The influence of stacking sequences and volume fraction of multiphase MEE materials on critical buckling temperature and vibration behaviour is investigated. The influence of coupling effects on critical buckling temperature and vibration behaviour is also studied.

The critical buckling temperature is higher for MEE axisymmetric cylinder as compared to elastic cylinder.

Linear thermal buckling and vibration analysis of MEE axisymmetric cylinders are studied using the finite element approach. The structure can be used for active vibration control, sensors and actuators. Studying the buckling and vibration behaviour of such structures and influence of coupling effect is extremely useful for the design of magnetoelectroelastic structures.

Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore aims to give the reader an encyclopaedic view on the subject. The bibliography at the end of the paper contains 2,025 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1992‐1995.

Nowadays, various software is available for simulating physical processes in induction heating. The software is often limited in its ability to simulate the billet movement, sometimes assuming uniform distribution of voltages on the inductor winding, uniformity of the physical properties of the billet, etc. The mathematical model of moving cylindrical ferromagnetic billets described in this paper takes into account the billet's movement, the billet phase heterogeneity and the nonuniformity of the supply voltage distribution in the inductor turns. The paper aims to discuss these issues.

The research methodology is based on FEM analysis of the coupled problem, including the electromagnetic and thermal boundary problem with additional algebraic equations, using Comsol 3.5a software.

The electromagnetic and temperature field in the billet and the voltage distribution on the winding turns have been calculated. The phase distribution in the billet has been predicted. Significant interaction of the nonuniformity of the supply voltage distribution, the billet's movement, the billet phase heterogeneity and side effect on the ends of the inductor have been shown.

The results received can be used for designing the induction heating unit for moving cylindrical billets made from ferromagnetic material and improving their characteristics.

Investigation of moving cylindrical ferromagnetic billets induction heating can be done by numerical solving the coupled problem including the electromagnetic and thermal boundary problem with additional algebraic equations for the supply voltage distribution.

Generator maintenance scheduling (GMS) is an essential task for electric power utilities as the periodical maintenance activity enhances the lifetime and also ensures the reliable and continuous operation of generating units. Though numerous meta-heuristic algorithms have been reported for the GMS solution, enhancing the existing techniques or developing new optimization procedure is still an interesting research task. The meta-heuristic algorithms are population based and the selection of their algorithmic parameters influences the quality of the solution. This paper aims to propose statistical tests guided meta-heuristic algorithm for solving the GMS problems.

The intricacy characteristics of the GMS problem in power systems necessitate an efficient and robust optimization tool. Though several meta-heuristic algorithms have been applied to solve the chosen power system operational problem, tuning of their control parameters is a protracting process. To prevail over the previously mentioned drawback, the modern meta-heuristic algorithm, namely, ant lion optimizer (ALO), is chosen as the optimization tool for solving the GMS problem.

The meta-heuristic algorithms are population based and require proper selection of algorithmic parameters. In this work, the ANOVA (analysis of variance) tool is proposed for selecting the most feasible decisive parameters in algorithm domain, and the statistical tests-based validation of solution quality is described. The parametric and non-parametric statistical tests are also performed to validate the selection of ALO against the various competing algorithms. The numerical and statistical results confirm that ALO is a promising tool for solving the GMS problems.

As a first attempt, ALO is applied to solve the GMS problem. Moreover, the ANOVA-based parameter selection is proposed and the statistical tests such as Wilcoxon signed rank and one-way ANOVA are conducted to validate the applicability of the intended optimization tool. The contribution of the paper can be summarized in two folds: the ANOVA-based ALO for GMS applications and statistical tests-based performance evaluation of intended algorithm.

Computation have been made of the three‐dimensional flow field development, chemical reaction and combustion processes in a typical afterburner system under both isothermal and reacting flow conditions. The calculations are based upon a numerical solution of the time‐averaged transport equations for mass, momentum, turbulence kinetic energy, dissipation rate, enthalpy and species concentrations using a finite‐volume formulation. The physical models include the k—ε turbulence model, the eddy break‐up model, a two‐step reaction model, a droplet vaporization and combustion model and six‐flux radiation model. The mean flow structures are presented in important longitudinal and cross‐sectional planes which show certain striking similarities and contrasting differences for isothermal and reacting flows. The flame stabilizer flow is shown to be dominated by a complex combination of recirculation and vortex patterns. Combustion alters convergence and mixing flow patterns downstream of the flame stabilizer, thus influencing the selection of the fuel injection system. The predicted reacting flow parameters identify a number of design parameters such as fuel injector location, high degree reaction zone, nozzle opening area and the corresponding fuel flow rate.