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1
Content available remote Non-linear modelling of elastic hysteretic damping in the time domain
EN
Elastic hysteretic damping is defined as the dissipation of energy at a rate that is weakly dependent on frequency of vibration. In this article, we propose that the elastic hysteretic damping can be achieved by a simple modification to the viscous damping model. The proposed modification is based on computing an instantaneous correction factor that recursively depends on the state variables of the system. This correction factor is related to the rate by which the velocity changes with respect to the displacement. The new model compares quite favourably with the other existing solutions in the time-domain and differences between the solutions become evident for higher damping ratios. It is found that the new model predicts consistently the weak variation in the loss factor as a function of frequency. In addition to its simple mathematical formulation, the proposed model is superior to the existing solutions in that it does not require knowledge of the past history of motion neither the knowledge of the excitation frequency and is extensible to any type of loading. Various aspects pertaining to the linearity of the proposed approach are finally discussed.
EN
This article presents research conducted on various polymer models imitating biological structures. Tests were conducted using a newly developed research method described in [1]. The purpose of our research was to check if the measuring system [1] is able to distinguish multilayer samples. Test materials were two different polymer models which were subjected to pressure in the central point. Marked points on the external surface of the sample were followed during the measurement. The arrangement of points on the image allowed to reconstruct the 3D surface of the sample and to determine the displacement of the analysed points. Measurements were repeated 10 times to ensure the representativeness (credibility) of the conducted research. Statistical tests and artificial neural networks (ANN) were used to classify the examined samples. We used 5-fold cross-validation for training and validating the ANN. The entire set of 75 cases was divided into 5 equinumerous subsets. The obtained results suggest that the proposed method distinguished between the tested samples on the basis of results. Analysed materials react differently to the given mechanical factor.
EN
The article reports the application of the mathematical theory of hysteresis to soil dynamics to characterise its behaviour under the action of cyclic loads. Based on appropriate laboratory experiments for a given soil, the achieved values were verified in simulations. The cycle shapes of stress–strain shear response for all strain levels and different combinations of static and cyclic shear stress loading were replicated. For proper characterisation in the case of repeated loads, the model incorporates the phenomenon of degradation of the structure and generation of excess pore pressure in considering its continuous variation throughout the loading process using an energy approach. The model is defined by parameters with physical interpretations that are evident from the tests.
EN
This paper presents a mobile ferrograph system for measurement of magnetic parameters of ultrahigh permeability alloys. The structure of developed system is described, as well as exemplary measurement results of Co67Fe3Cr3B12Si15 alloy used in space applications are presented.
5
Content available Investigation of the memristor nonlinear properties
EN
The study of nonlinear systems is an important research topic for scientists and researchers. Memristor, for a long time, it remained just as a theoretical element and rarely appeared in the literature because of having no simple and practical realization. In this paper, we reviewed the theoretical substantiation of the memristor and conducted a practical study of its nonlinear properties using the memristor company KNOWM of series BS-AF-W 16DIP. We also investigated the characteristics of the memristor via the LabView environment.
PL
Badanie systemów nieliniowych jest ważnym tematem dla badaczy i naukowców. Memrystor przez długi czas pozostawał elementem teoretycznym i rzadko pojawiał się w literaturze z powodu braku prostej i praktycznej realizacji. W tym artykule zostały przedstawione teoretyczne uzasadnienie memrystora i badania jego właściwości nieliniowych na przykładzie memrystora firmy KNOWM serii BS-AF-W 16DIP. Zostały przeprowadzone badania charakterystyk memrystora w środowisku LabView.
EN
This paper addresses the problem of modeling the nonlinear coil used for ferroresonant circuit analysis. The effect of ferroresonance is described and a general modeling approach is presented. The hysteresis modeling problem is also shortly discussed, on the example of a ferromagnetic coil. A brief overview of available literature and contributors to this area are provided. A series RLC circuit supplied from an AC source is discussed. The application of the fractional derivative in the modeling of an iron core coil is presented and suggestions of model implementations are given. The computations performed are illustrated by means of waveform data obtained from computer simulations and compared with those obtained from measurements performed in a specially prepared laboratory setup.
7
Content available Open loop control of piezoelectric tube transducer
EN
This paper is focused on the open loop control of a piezoelectric tube actuator, hindered by a strong hysteresis. The actuator was distinguished with 22 % hysteresis, which hinders the positioning of piezoelectric actuator. One of the possible ways to solve this problem is application of an accurate analytical inversed model of the hysteresis in the control loop. In this paper generalized Prandtl-Ishlinskii model was used for both modeling and open loop control of the piezoelectric actuator. Achieved modeling error does not exceed max. 2.34 % of the whole range of tube deflection. Finally, the inverse hysteresis model was applied to the control line of the tube. For the same input signal (damped sine 0.2 Hz) as for the model estimation the positioning error was max. 4.6 % of the tube deflection. Additionally, for a verification reason three different complex harmonic functions were applied. For the verification functions, still a good positioning was obtained with positioning error of max. 4.56 %, 6.75 % and 5.6% of the tube deflection.
8
Content available remote Curves of thermodynamic states in some fluids with dispersion
EN
Variations in the thermodynamic state of a dispersive medium, caused by sound, are studied. A bubbly liquid and a Maxwell fluid are considered as examples. Curves in the plane of thermodynamic states are plotted. They are in fact pictorial images of linear relations of excess pressure and excess density in the acoustic wave which reflect irreversible attenuation of the sound energy. The curves account for the nonlinear generation of the entropy mode in the field of sound. In the case of Maxwell fluids, loops may form under some conditions. Curves and loops for some kinds of stationary waveforms and impulse sound are discussed and compared.
EN
In this article a passive system, which exploits the properties of the Coulomb friction and leads to high affordability of controlling shocks and vibrations by means of cheap devices is presented. The friction force developed by the proposed device is dependent on the motion stroke by convenient modulation of contact force between the elements of friction coupling. For providing the system self-centring properties or necessary vertical load capacity, coil springs can be incorporated into the device structure. The device hysteresis characteristic can be simply adjusted to comply with requirements of the considered application. A general mathematical model of device dynamic behaviour is developed and applied to shock and vibration isolation systems. The article presents a novel passive device with variable friction which hysteresis force-displacement characteristics have “butterfly” shape, achieved by appropriate design of friction coupling. This shape of hysteresis loops can mitigate the drawbacks of constant friction devices. The schematic of mechanical systems to analyse the dynamic behaviour of shock and vibration isolation systems with variable friction device are shown.
EN
Measurements of dynamic surface tension were carried out in aqueous systems (water or 0.1 mM Triton X-100) comprising nanoparticles formed from chemically modified polyaldehyde dextran (PAD). The nanostructures, considered as potential drug carriers in aerosol therapy, were obtained from biocompatible polysaccharides by successive oxidation and reactive coiling in an aqueous solution. The dynamic surface tension of the samples was determined by the maximum bubble pressure (MBP) method and by the axisymmetric drop shape analysis (ADSA). Experiments with harmonic area perturbations were also carried out in order to determine surface dilatational viscoelasticity. PAD showed a remarkable surface activity. Ward-Tordai equation was used to determine the equilibrium surface tension and diffusion coefficient of PAD nanoparticles (D = 2.3×10-6 m2/s). In a mixture with Triton X-100, PAD particles showed co-adsorption and synergic effect in surface tension reduction at short times (below 10 s). Tested nanoparticles had impact on surface rheology in a mixed system with nonionic surfactant, suggesting their possible interactions with the lung surfactant system after inhalation. This preliminary investigation sets the methodological approach for further research related to the influence of inhaled PAD nanoparticles on the lung surfactant and mass transfer processes in the respiratory system.
EN
The paper presents the design procedure and elaborated software for designing calculation of the shape memory alloy (SMA) actuator. The thermo-mechanical behavior of a linear SMA actuator has been studied. The experimental set-up was especially designed to perform the thermo-mechanical characterization of SMA wires. The stroke (s) – temperature (T) hysteresis characteristics have been determined. The cycle of heating and cooling has been performed under a constant load. The model for the SMA actuator s – T behavior has been proposed and successfully implemented. The selected results and conclusions have been presented. The concept proposal of the linear actuator using the SMA wire has been given.
EN
This paper presents an experimental and numerical investigation on the steel plate shear walls with beam-only-connected web plates (SSW-BO). These systems feature an alternative to the traditional type of steel shear walls through separating the lateral load resisting system from the primary columns. A possible drawback of SSW-BO is its reduced shear capacity compared with fully-connected web plates. High yield strength (HYS) web plate may develop shear capacity of these systems. The seismic behavior of the SSW-BO systems are experimentally investigated under cyclic quasi-static loading and compared considering two material properties and two different circular opening ratios. Shear strength, ductility, and energy dissipation capacity of HYS panels are higher than those of low yield strength (LYS) panels by as much as roughly 70%, 10% and 30%, respectively. The use of HYS web plates in SSW-BO systems appeared to be a promising solution to compensate the concerns regarding the low shear capacity and low energy dissipation resulting from separation steel plate from the columns. Moreover, the finite element software ABAQUS was used to investigate the behavior of SSW-BO systems by nonlinear analysis. A comparison between the experimental and numerical results showed excellent agreement.
EN
The paper deals with the possibilities of measuring the residual displacement or hysteresis on the lateral direction of the movement forces caused by the cutting forces of the machining. A special adjustment of laser interferometry assemblies was used for measurement. The measurement results indicate that the positioning accuracy in addition to the cutting forces also influences the position of the displaced moving substances and the temperature. The complex effect of these parameters is greatly dependent on the design of the machine.
EN
One of the factors affecting the accuracy of Coordinate Measuring Systems is hysteresis of a probe head. It is important especially in case of touch trigger probes and should be taken into account during the determination of probing strategy. In this article, the authors try to assess how this phenomenon affects the accuracy of five axis coordinate systems which utilize articulating probe head. Such systems allow to measure point coordinates using rotary movements of the head what introduces changes to the probing process. The experiments presented in this paper are based on multiple measurements of the reference elements such as gauge blocks and standard ring.
EN
Our work involved experimental study of the influence of actomyosin complexes and the main structural components of the myocardial tissue – connective tissue collagen framework and cardiomyocytes – on the characteristics of viscoelastic hysteresis at different frequencies. In this paper a new method was introduced for the analysis of the viscoelastic characteristics of the force hysteresis in the isolated myocardial preparation for the assessment of mechanical energy expenditure in the tension-compression cycle. We established that basic myocardial structures have an impact on the to the characteristics of the viscoelastic hysteresis in many ways. It was shown that in rat’s myocardium cardiomyocytes one main factor that define the stiffness and viscosity of the myocardium in the physiological range of deformations, while binding of calcium ions with EGTA and calcium removal of sarcoplasmic reticulum with caffeine reduces viscoelasticity by ~30% and collagen framework is responsible for about 10% of viscoelasticity. It was revealed that in the physiological range of the hysteresis frequencies (3 to 7 Hz) expenditure of mechanical energy per unit of time increases linearly with increasing frequency. We proposed the structural and functional model that adequately describes the characteristics of the viscoelastic hysteresis in myocardial preparation in the range of strains and frequencies being under study.
EN
The paper discusses friction phenomenon between the pushbelt (or chain) in the continuously variable transmission. This type of transmission is becoming more and more popular. It is so due to the technical progress last years and its indisputable advantage over conventional transmissions. It enables us to use the full characteristic of the engine. The introduction describes the issue, principles of the transmission’s operation, the construction of the steel pushbelt and a scheme of forces acting on a single belt’s steel element (segment). In the next part, the article explains the need of researches and their impact on the transmission’s proceeding. Moreover, a simplified model of the test bench with description of the proposed tests needed to elaborate sought relationships is included in the paper.
EN
Bio-polyols based on rapeseed oil were used to produce flexible polyurethane foams (FPURF). The bio-polyols were obtained on a laboratory and industrial scale with the two-step method involving epoxidation of double bonds in rapeseed oil and opening of oxirane rings with different alcohols, such as isopropanol (iP) and diethylene glycol (DEG). The impact of bio-polyols production scale on selected physical and mechanical properties of FPURF was analyzed. The applied bio-polyols differed slightly by hydroxyl number, functionality, and water content. It was found that the scale of bio-polyol production has no significant impact on FPURF properties such as apparent density, hardness, hysteresis, support factor, and resilience. However, it was observed, that the addition of the bio-polyol to polyurethane (PUR) formulation had the impact on the FPURF properties as compared to the reference foams that were not modified with the bio-polyols. Moreover, a continuous method was used to prepare FPURF samples modified with different rapeseed oil-based polyols. For this purpose mixing-dosing device with conveyor line was used to synthesize the foams. It was found that the replacement of petrochemical polyols with the bio-polyols resulted in lower reactivity of the modified for- mulations and the amount of catalysts had to be increased. Furthermore, the foams hysteresis, support factor, and hardness were higher, especially for foams modified with the bio-polyol that contained DEG in its structure. Moreover, the fatigue tests were performed and the results showed a beneficial effect of the bio-based polyols on the functional properties, a.o. support factor of flexible foams.
PL
Bio-poliole z oleju rzepakowego, wytworzone w skali laboratoryjnej i przemysłowej, zastosowano wsyntezie elastycznych pianek poliuretanowych (FPURF). Bio-poliole otrzymano metodą dwuetapową przez epoksydację wiązań podwójnych w oleju rzepakowym, a następnie przez otwarcie pierścieni oksiranowych za pomocą izopropanolu (iP) oraz glikolu dietylenowego (DEG). Zbadano wpływ rodzaju bio-poliolu (także tego samego rodzaju, ale otrzymanego w różnej skali) na wybrane właściwości fizyczne i mechaniczne FPURF. Zastosowane bio-poliole różniły się między sobą nieznacznie liczbą hydroksylową, funkcyjnością i zawartością wody. Stwierdzono, że skala produkcji polioli nie ma istotnego wpływu na właściwości FPURF, takie jak: gęstość pozorna, twardość, histereza, współczynnik komfortu i odbojność. Zaobserwowano jednak wpływ modyfikacji za pomocą różnych bio-polioli na właściwości FPURF w porównaniu z właściwościami niemodyfikowanej pianki referencyjnej. Pianki FPURF otrzymano również stosując metodę ciągłą z użyciem urządzenia dozująco-mieszającego wraz zlinią do przesuwu form z mieszaniną reakcyjną. Stwierdzono, że zastąpienie polioli petrochemicznych bio-poliolami powoduje zmniejszenie reaktywności kompozycji poliuretanowych, co spowodowało konieczność zwiększenia ilości katalizatorów. Ponadto, zaobserwowano wzrost histerezy, współczynnika komfortu i twardości, szczególnie w wypadku pianek zawierających bio-poliol z wbudowanym DEG. Wyniki badań zmęczeniowych wykazały korzystny wpływ bio-polioli na właściwości użytkowe, m.in. na współczynnik komfortu pianek elastycznych.
18
Content available remote Simulation tests of relay valve in the context of its resistances to motion
EN
The article presents the description of the cylinder relay valve designed and made by the Rail Vehicles Institute "TABOR". The individual components of its construction were characterized and it was selected those that have the significant influence on change of resistances to motion of the relay valve. The currently applicable criteria concerning the operating parameters of the cylinder relay valve are presented. The selected results of the tests which consisted in determining the impact of resistances to motion on change of the hysteresis values and the correctness of operation of the relay valve are presented. The stand, on which the simulation tests of relay valve operation were carried out, and the stand for measurements of resistances to motion are shown. The article also presents a computer simulation model in which the results were verified.
PL
W artykule przedstawiono opis przekładnika ciśnienia cylindrowego zaprojektowanego i wykonanego przez Instytut Pojazdów Szynowych „TABOR”. Scharakteryzowano poszczególne elementy składowe jego budowy oraz wytypowano te, które mają istotny wpływ na zmianę oporów ruchu przekładnika ciśnienia. Przedstawiono aktualnie obowiązujące kryteria dotyczące parametrów działania przekładnika ciśnienia cylindrowego. Zaprezentowano wybrane wyniki badań, które polegały na ustaleniu wpływu oporów ruchu na zmianę wartości histerezy oraz poprawności działania przekładnika ciśnienia. Pokazano stanowisko, na którym przeprowadzono badania symulacyjne działania przekładnika ciśnienia oraz stanowisko do pomiarów oporów ruchu. W artykule przedstawiono także komputerowy model symulacyjny, w którym weryfikowano wyniki badań.
EN
In this paper, analysis of a half-car model with linear and nonlinear semi-active dampers is performed. Using Matlab-Simulink software, a response of the system to a harmonic excitation of variable frequency and to an impulse excitation is found. The effect of both the distribution of spring-supported mass and the asymmetry of the support on the frequency characteristics of velocities and displacements at the mounting points of the dampers are analyzed. Additionally, characteristics of forces generated by the semi-active dampers and the response of the system when crossing an obstacle are determined.
EN
The article presents dilatometric research results of composite alloy (in-situ) for combustion engines piston. Researches were performed with a precise dilatometer. Alloy's research test stand and test results including relative elongation, course of derivative of dimension increasing versus time with phase transition and course of coefficient of linear thermal expansion α for composite alloy versus temperature are presented in the article. Novel composite alloy allows getting a minimum difference of the coefficient of linear thermal expansion α during heating and cooling. In particular, the chemical composition of the novel composite silumin alloys; ATD of standard alloy – silumin Ak12 and novel composite alloy; schema of research stand and view of the measuring-head of the extension; course of the coefficient of linear thermal expansion α versus temperature during heating and cooling for the standard alloy and novel composite alloy; course of the relative piston elongation ΔL/Lo versus temperature during heating and cooling for the standard alloy and novel composite alloy; course of the derived function of the extension in relation to time dL/dt versus temperature for the standard alloy on pistons and novel composite alloy; course of the relative elongation in function of time during ageing of composite alloy at the temperature of 200°C with two-stage ageing process; course of the relative elongation in function of time during ageing of composite alloy at the temperature of 200°C for the first stage and second stage are presented in the article.
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