
Dynamics of a cantilever beam with piezoelectric sensor: Parameter identification
Cimrman, Robert ; Kolman, Radek ; Musil, Ladislav ; Kotek, Vojtěch ; Kylar, Jaromír
The piezoelectric materials are electroactive materials often applied for realtime sensing or structural health monitoring, both important research topics in dynamics. Mathematical models of such structures have to allow also for the external electrical circuits and contain several material parameters that need to be identified from experiments. We present a model of a simple experiment involving dynamics of a cantilever beam with an attached piezoelectric sensor excited by a suddenly removed weight. The external circuit can be taken into account as having either a finite or infinite resistance. We also outline the parameter identification procedure based on automatic differentiation and present the experimental and numerical results.


Dynamics of a cantilever beam with piezoelectric sensor: Experimental study
Kolman, Radek ; Kylar, Jaromír ; Kotek, Vojtěch ; Cimrman, Robert ; Musil, Ladislav
Online and realtime sensing and monitoring of the health state of complex structures, such as aircraft and critical parts of power stations, is an essential part of the research in dynamics. Several types of sensors are used for sensing dynamic responses and monitoring response changes during the operation of critical parts of complex systems. The piezoelectric (PZ) materials belong to one group of electroactive materials, which transform mechanical deformation into an electrical response. For example, PZ ceramics or PVDF foils are employed for online sensing of the time history of mechanical deformation. Experimentally obtained response of a cantilever beam structure with a glued PZ sensor is the case of interest in this contribution. During the transient problem of the beam loaded by suddenly interrupted load due to the weight of a mass at the end of the beam, the time history of normal velocity at a point on the beam surface has been measured by a laser vibrometer and parallely, the output voltage on the PZ sensor has been measured by an electric device. The experimental data in the case of the first eigenfrequency is in good agreement with the value given by the formulae from the theoretical modeling of free vibration of a linear beam.

 

Energy from Agricultural Land
Šatra, Jan ; Bičík, Ivan (advisor) ; Musil, Ladislav (referee)
Thesis is concerned with relation of usable energy and space as it's widely spread source. For this purpose are introduced not only a few indicators suitable to energy management description, but also principles of environmental assessment thinking are expained, as these help to distinguish the really sustainable ways of deriving energy from space. As examples of energyfromspace extraction are introduced photovoltaics, liquid biofuels and fast growing energy plants. After a brief entry to heat supply problematics, focus is remains on a simple case study: quantifying relationship between local heat demand and local potential production of solid biomass from short rotation coppice. This so far rather hypothetic relation is examined at the municipal level, while Central and South Bohemia regions are the target area. Soil characteristics and population census data (2001) about residental habitats are used.


Aplikovatelnost nové metody pro lepší diskretizaci valmi malých hloubek vniku
Musil, Ladislav
The paper deals with tests of a new suggested method for an easier discretisation of thin layers of electromagnetic field penetrating into a conducting material. First the principle of the new method and its derivation is described. Comparison of computation with and without the transformation follows. The comparison is done on several very simple arrangements of induction heating of a ferromagnetic material. The computation were carried out by the FEM based professional code of FEMLAB supplemented with single purpose scripts written by the author in MATLAB and MATHEMATICA.


Možnosti elektromagnetického čerpání tekutých kovů a jejich numerické modelování
Musil, Ladislav ; Doležel, Ivo ; Karban, P. ; Ulrych, B. ; Barglik, J.
Electromagnetic pumps and feeders of molten metals are widely spread devices used in many branches of industry. Their operation is, however, accompanied by a high consumption of energy. Improvement of their efficiency and optimization of their design requires detailed knowledge of the relevant electromagnetic (and sometimes also thermo and hydrodynamic) processes. The paper deals with the principles of operation of such devices, presents their mathematical models and techniques of their numerical solution. The theoretical analysis is illustrated on typical examples providing the fundamental ideas about their operation parameters and characteristics.


Techniky zpracování tuhých a tekutých kovů založené na elektromagnetické indukci
Doležel, Ivo ; Šolín, Pavel ; Musil, Ladislav ; Ulrych, B. ; Karban, P. ; Barglik, J.
A lot of uptodate industrial technologies associated with treatment of solid and liquid metals are based on thermal and force effects of electromagnetic field. The fundamental process is induction heating of metals that precedes a number of consequent operations such as tempering, drying, melting, stirring, hardening, hot pressing etc. The paper summarizes physical essence of the above processes (that usually represent complex coupled problems) and presents their mathematical and computer models as well as possible methods of their solutions.


Porovnání 2D a 3D modelu dávkovače zinku
Mach, M. ; Musil, Ladislav
The paper deals with the mathematical and computer modelling of electromagnetic zinc feeder, which is a device for exact dosing of molten zinc. 2D and 3D models of the feeder were developed, solved and the results were compared and discussed. Computations were carried out by the professional FEMbased codes FEMLAB, OPERA, QuickField and a number of singlepurpose user procedures written by the authors


Polařský a obvodový model dávkovače zinku
Musil, Ladislav ; PraglowskaGorczynska, Z.
Electromagnetic feeders of molten metals are used in some industrial technologies, particularly for accurate dosing. Mathematical model of such devices represents a complicated coupled task characterised by interaction of electromagnetic, temperature and flow fields. The paper deals with numerical computation of several important quantities of the device providing its circuit parameters
