Petr Kropík

Accurate Control of Position by Induction Heating-Produced Thermoelasticity

An alternative possibility of highly accurate control of position is suggested, realized by a simple device with a cylindrical dilatation element that works on the principle of thermoelasticity produced by induction heating. The paper describes the device, presents its complete mathematical model in common with the methodology of its numerical solution, and also the algorithm of the control process. The theoretical analysis is illustrated by a typical example, whose results are discussed.

Higher-order finite element modeling and optimization of actuator with non-linear materials

An electromagnetic actuator with nonlinear structural parts is modelled and optimized. The aim of the optimization is to obtain a flat static characteristic and reach the highest possible force acting on its plunger (manufactured of permanent magnet) at the smallest possible dimensions. The solution of the problem is carried out numerically by the professional software package COMSOL Multiphysics fully controlled by a number of special in-house scripts and procedures. First, two deterministic optimization algorithms are applied to evaluate several different actuator configurations and determine the optimal actuator design from the viewpoint of the maximum force acting on its movable part. Then, a genetic algorithm is used for a multiobjective optimization providing the flattest possible static characteristic. The methodology is illustrated by a typical example whose results are discussed.

Induction heating of thin metal plates in time-varying external magnetic field solved as nonlinear hard-coupled problem

A novel mathematical model of local induction heating of very thin metal plates in an external time-variable magnetic field is suggested. Distribution of eddy currents induced in the plate is modelled by electric vector T-potential and thermal fluxes in the systems are expressed in terms of heat sources and sinks. Analysed are also the thermoelastic displacements in the plate, their back influence on the discretization mesh and distribution of the electromagnetic and thermal quantities. Numerical solution of the problem is carried out in the hard-coupled formulation. The methodology is illustrated by a typical example whose results are discussed.

Optimized control of field current in thermoelastic actuator for accurate setting of position

A novel device for control of position working with accuracies on the order of 10^-^5-10^-^3m is proposed. The device has no movable parts. It works with an inductively heated metal cylindrical element of appropriate dimensions, whose longitudinal dilatation of thermoelastic origin is controlled by the harmonic field current in the inductor. The principal aim of the paper is to find such a time evolution of the field current that allows reaching the required dilatation in the shortest time possible.

Bayes approach to solving T.E.A.M. benchmark problems 22 and 25 and its comparison with other optimization techniques

The Bayes approach is used for solution of benchmark problems 22 and 25. The main purpose of the paper is to evaluate its applicability for solving complex technical problems (up to now, this technique was only very rarely used in the domain of such tasks). The parameters of this approach are compared with characteristics of several other heuristic and deterministic optimization techniques implemented in commercial code COMSOL Multiphysics and own open-source application Agros Suite. The results confirm that the Bayes approach is superior in a number of aspects and for the solution of real-life tasks it represents a powerful and prospective alternative to existing optimization methods

Minimization of force and thermal effects in bus bars

Force and thermal effect in bus-bar systems are investigated. The goal of this research is to find the configuration exhibiting their minimum possible values. The computations are carried out numerically, using the fully adaptive higher-order finite element method. The methodology is illustrated with several examples whose results are discussed.

Utilization of algebraic multigrid for solving electromagnetic field by HP-FEM

Comparison of open-source libraries for solving systems of algebraic equations is carried out. Attention is paid mainly to solvers (or preconditioners) using the method called algebraic multigrid. For comparison, several direct and iterative solvers were chosen, such as MUMPS, UMFPACK, TRILINOS, PARALUTION and PETSc. Utilization of these packages is shown on two examples.

Electromagnetic field along the power overhead line at point where the line route changes direction

Purpose – High-voltage overhead lines produce low-frequency electromagnetic fields around them. These fields are easy to compute wherever the line route is straight, as opposed to places where its direction is changed. The purpose of this paper is to perform a numerical analysis of an electromagnetic field occurring along a high-voltage overhead line at the places of the changed direction and to compare the results with the exposure limits for low-frequency electromagnetic fields in order to assess their effects on living organisms. Design/methodology/approach – The computation was conducted in the MATLAB SW by means of a combination of integral and differential methods in a three-dimensional (3D) arrangement, taking into account the location and shape of the tower. Special procedures within the MATLAB software had to be coded. Findings – Within the research, the following electromagnetic field quantities were computed: the distribution of electric field strength, magnetic flux density, Poynting vector, e...

Steel buried pipeline influenced power overhead line

The influence of three-phase overhead power lines on parallel steel pipelines is investigated. The principal monitored value is their resistive heating. The computations are realized numerically, by the finite element method. The comparison of adaptive techniques in finite elements methods is shown using software Agros 2D and COMSOL Multiphysics. The methodology is illustrated by two examples whose results are discussed.