Wyniki wyszukiwania - BazTech

1

Upgrading of vibrating compactor of the railway track ballast of VPO-3000 machine

Lee S., Akhmetov M., Ibraimov A., Taran M.

Transport Problems

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2012

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T. 7, z. 4

95-104

EN

In the course of work a new vibrating compactor with single-direction inertial forces according to the authors’ innovative license is applied. Examination of possible dependence on substantiation of the new vibrating device parameters is shown. The new single-direction vibrating device for road crushed rock compaction allows decreasing vibration to the machine frame and increasing its working capacity. The new vibrating device’s efficiency to 11,7% increases the existing ones.

2

Influence of shape of side face on the force-displacement characteristic of electromagnetic actuator on the base of field model

Nowak L., Knypiński Ł., Radziuk K.

Poznan University of Technology Academic Journals. Electrical Engineering

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2010

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No. 62

25-35

EN

An algorithm and computer software for the optimization of the structure of electromagnetic linear actuator is presented. For the simulation of the actuator the field model has been applied. Numerical implementation is based on the finite element method. In order to account for the non-linearity of the ferromagnetic core the Newton-Raphson procedure has been employed. Using elaborated software the force-displacement characteristics of the actuator have been calculated. The influence of apex angle of the plunger and the extent of magnetic circuit saturation on the shape of these characteristics has been investigated.

3

Long-time stability of shape memory actuators for pedestrian safety system

Strittmatter J., Gümpel P., Zhigang H.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 34, nr 1

23-30

EN

Purpose: Pedestrian safety systems play an increasing significant role to reduce injuries and fatal casualties caused by accidents. One automotive safety system for pedestrian protection is the bonnet lifting system. Using shape memory alloys (SMA) the existing systems could be simplified, performing the same function through new mechanisms with reduced size, weight and costs. A drawback for the use of SMA in such safety systems is the lack of material knowledge concerning the durability of the switching function. This paper gives an introduction to existing bonnet lifting systems for pedestrian protection, describes the use of quick changing SM actuators and presents the testing facilities and some results of the study concerning the long-time stability of the tested NiTi-wires. Design/methodology/approach: A large number of NiTi-wires was trained, exposed up to four years at elevated temperatures and tested regarding their phase change temperatures, times and strokes. Findings: It was found out that Ap-temperature is shifted towards higher temperatures with longer exposing periods and higher temperatures. However, in the functional testing plant a delay in the switching time could not be detected. Research limitations/implications: For future works it is suggested that more NiTi-specimens at longer ageing periods should be tested, stress should also be applied by a constant load and the functional testing plant should be further optimized. Practical implications: It can be concluded, that the use of quick changing SM actuators in safety systems could simplify the mechanism, reduce maintenance and manufacture cost and should be insertable also for other automotive applications. Originality/value: This paper gives some answers concerning the long-time stability of NiTi-wires that were missing till now. With this knowledge the number of future automotive applications using SMA can be increased.

4

Damping of vibrations through torsion damper during starting power transmission system.

Skup Z.

Archive of Mechanical Engineering

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2004

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Vol. LI, nr 2

165-180

EN

This paper presents a study of the damping of nonlinear vibrations in a two-mass model od mechanical system containing a torsion damper. The starting of a system by harmonic excitation is considered on the assumption of uniformly varying frequency and constant amplitude of the forced moment. Simultaneous structural friction phenomena (passive damping) and piezoelectric effect (active damping) have been considered as well. The problem is considered on the assumption of a uniform unit pressure distribution between the contacting surfaces of friction discs and plunger. The aim of the analysis is to asses the influence of angular acceleration, unitary pressure, external load and electric parameters on the resonance curves of the starting vibrations. The equations of motion of the tested system were solved by means of the Krylov-Bogolubov-Mitropolski method and digital simulation method.

PL

Praca dotyczy badania tłumienia drgań nieliniowych układu mechanicznego o dwóch stopniach swobody zawierającego tłumik drgań skrętnych. Rozważany jest rozruch układu przy wymuszeniu harmonicznym z jednostajnie zmienną częstością o stałej amplitudzie momentu wymuszającego. Uwzględniono tłumienie drgań wykorzystując zjawisko tarcia konstrukcyjnego (tłumienie pasywne) i efekt piezoelektryczny (tłumienie aktywne). Zagadnienie rozpatrywane jest przy założeniu równomiernego rozkładu nacisków jednostkowych występujących pomiędzy współpracującymi powierzchniami tarcz ciernych i bezwładnika. Zbadano wpływ przyspieszenia kątowego, nacisku jednostkowego, obciążenia zewnetrznego oraz współczynnika wzmocnienia na krzywe rezonansowe drgań rozruchowych. Równania ruchu badanego układu mechanicznego rozwiązano wykorzystując asymptotyczną metodę Kryłowa-Bogolubowa-Mitropolskiego i metodę symulacji cyfrowej.

5

Fuzzy-Logic Fault Diagnosis of Industrial Process Actuators

Kościelny J. M., Syfert M., Bartyś M.

International Journal of Applied Mathematics and Computer Science

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1999

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Vol. 9, no 3

653-666

EN

The paper presents an idea of decomposition of diagnostic tasks in complex systems. Such decomposition consists in splitting basic diagnostic functions into lower-level units existing in decentralised structures of automatic control and supervision of the process. An example of a unit that realises this concept and includes a positioner that controls and diagnoses an assembly consisting of a servomotor and a pneumatic control valve is also given. An application of fuzzy logic to the actuator diagnosing algorithm is presented and results of the corresponding fault detection tests in an industrial environment are discussed.

6

Excitation zones optimization for piezoelectric structures

Bansevicius R., Kulvietis G., Mazeika D.

Archives of Civil Engineering

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1999

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Vol. 45, nr 2

137-146

EN

This paper presents a study of optimization of the electrodes dislocation of piezoelectric actuators. The following conditions of optimization problem are considered: to unify excitation voltage forms, to achieve reverse motion and maximum coefficient of efficiency. Realisation of this requirement means that generator has to supply voltage of constant frequency, amplitude and phase, reverse motion must be achieve only through changing the polarity of the electric flux and the surface of the piezodrive is fully covered with electrodes. When all aforementioned conditions are achieved, any mode shape of piezoelectric actuator could be obtained by changing polarity of the voltage, supplied to the particular electrode. In order to find the sign of the polarity, corresponding to the certain modal shape, the comparison must be done between directions of the vector of amplitude of the equivalent mechanical force and particular eigenvector of the actuator. If the direction of displacement eigenvector of the piezodrive and the vector of amplitudes of the equivalent mechanical force is the same or similar i.e. the angle is within the limits [—pi/2, pi/2], then the polarity of the voltage, supplied to particular electrode have initial sign. In other case the sign of polarity must be changed. FEM modelling is performed in calculating process. The results of calculations of excitation zones dislocation of the piezoelectric actuators are shown under two optional conditions of fixing.

PL

Praca przedstawia optymalizację rozmieszczenia elektrod w aktuatorach piezoelektrycznych. Rozważa się następujące warunki zagadnienia optymalizacyjnego: ujednolicenie kształtu napięcia wzbudzjącego, uzyskanie ruchu wstecznego i maksymalnego współczynnika sprawności. Spełnienie tych wymagań oznacza, że generator musi dostarczać napięcia o stałej częstotliwości, amplitudzie i fazie; ruch wsteczny musi być uzyskany wyłącznie przez zmianę biegunowości przepływu, a powierzchnia napędu piezoelektrycznego musi być całkowicie pokryta elektrodami. Gdy wszystkie wymienione wyżej warunki są spełnione, można uzyskać dowolny kształt działania aktuatora przez zmianę biegunowości napięcia dostarczanego do danej elektrody. Aby znaleźć znak biegunowości odpowiadającej danemu kształtowi modalnemu, należy dokonać porównania między kierunkami wektora amplitudy odpowiedniej siły mechanicznej i szczególnego wektora własnego aktuatora. Jeśli kierunek wektora własnego przemieszczeń napędu piezoelektrycznego i wektora amplitud równoważnej siły mechanicznej jest taki sam lub podobny, tzn. kąt mieści się w granicach [—pi/2, pi/2], wtedy biegunowość napięcia dostarczanego do danej elektrody ma znak początkowy. W przeciwnym przypadku znak biegunowości musi zostać zmieniony. Modelowanie MES dokonuje się w trakcie procesu obliczeniowego. Wyniki obliczeń dotyczące rozmieszczenia stref wzbudzenia aktuatorów piezoelektrycznych są pokazane przy dwóch przykładowo założnych warunkach zamocowania.

7

Spreadability and spray actuators

El Yacoubi S., El Jai A., Karrakchou J.

Applied Mathematics and Computer Science

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1998

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Vol. 8, no 2

367-379

EN

Spreadability of distributed systems has been recently introduced (El Jai and Kassara, 1994; El Jai et al., 1995). The aim of this paper is to propose a new approach to spreadability based on considering actuators as generators of spreadability. This approach is related to ecological and environmental problems, like vegetation dynamics, where the actuators are assumed to be governed by a transport equation while the system is described by a diffusion model.

8

Composite adaptive SMC of nonlinear base isolated buildings with actuator dynamics

Luo N., De La Sen M., Rodellar J.

Applied Mathematics and Computer Science

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1998

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Vol. 8, no 1

183-197

EN

This paper addresses the problem of designing a robust active controller for nonlinear base isolated building structures in the presence of unknown seismic excitations, parametric uncertainties and actuator dynamics. A simple adaptation law is introduced to get available upper bounds for the unknown seismically excited nonlinearities. Adaptive composite output feedback sliding mode control schemes are proposed to drive the displacements of the base and structure to their zero equilibrium positions. A numerical simulation example is presented to illustrate the effectiveness of the proposed strategies to a ten-storey base isolated structure under the El Centro earthquake.