MECHANICS

Permanent URI for this communityhttps://repo.agh.edu.pl/handle/AGH/102766

Tytuł archiwalny!

Adres wydawniczy: Kraków : Wydawnictwa AGH, 2005-2009
ISSN: 1734-8927 e-ISSN: 2300-7060
Następny tytuł: Mechanics and Control (2010-2016)

Mechanics wydawana w latach 2005-2009. Kontynuowane w latach 2010-2016 pod tytułem Mechanics and Control

Roczniki i numery

Browse

Now showing 1 - 20 of 166

Access status: Open Access ,
Active control of vibrations of a three-axis gyroscopic platform on board of a flying object
(Wydawnictwa AGH, 2005) Koruba, Zbigniew; Styczeń, Jerzy
The work presents an algorithm for active control of vibrations of a three-axis gyroscopic platform during pre-programmed and stabilised operation on board of a flying object. The considerations focus on disturbances resulting from the flying object manoeuvres and short-duration pulses of external forces under the conditions of friction in the bearings and non-linear platform operation range.
Access status: Open Access ,
Podobieństwa i różnice w zakresie statyki sekcji obudów ścianowych
(Wydawnictwa AGH, 2005) Losiak, Stanisław; Ptak, Jan; Blaschke, Janusz
In the paper schemes of basic group of supports with distribution of loads for three types of units have been presented. It has been demonstrated that schemes with load distribution may be reduced to one collective scheme and a common mathematical description for various types of units may be presented. Application of the common description for testing the characteristics of the units of the same type were discussed. In general, equations for determining the static parameters of the support unit with stretcher cylinder were given. Static-stability characteristics of such a support unit on the basis of exemplary characteristics determined from mathematical description were discussed.
Access status: Open Access ,
Analiza techniczna i ekonomiczna rekonstrukcji czerpaków dla koparek kołowych SCHRS 4000 urabiających caliznę w KWB «Bełchatów»
(Wydawnictwa AGH, 2005) Badura, Sławomir; Łopata, Antoni Mieczysław
The paper presents technical and economical analysis of the reconstruction for symmetrical and asymmetrical bucket mounted on the bucket wheel excavators SchRs 4000 in the targets to dredging mineral.
Access status: Open Access ,
Semiactive control strategies for a fully suspended bicycle
(Wydawnictwa AGH, 2005) Plaza, Krzysztof
The purpose of this work is to present methods for designing semiactive vibration systems, which include mathematical models of vibrating structures. Thus aspects of model building, identification and verification are described in the paper as well as determination of the performance indices, choice of the damping technique, shock absorber modeling and algorithm selection. The article presents a semiactive vibration system analysis of a fully suspended bicycle. For all of the simulation experiments and serving as a reference for the identification experiment a phenomenological model of the bicycle was developed in the Simulink environment. The model was confronted with the real time experiments, which were conducted with the help of an electrical system. The necessity of the discussion of the various performance indices is underlined. Simple control strategy is tested on the bicycle.
Access status: Open Access ,
Determination of loss coefficient in selected elements of radial fan
(Wydawnictwa AGH, 2005) Fortuna, Stanisław
The article presents a method of measurement and calculation of pressure losses and loss coefficients for inlet cone and inlet chamber of the rotor. Cone coefficients and a total coefficient for a set of elements supplying the radial fan rim are presented and may constitute the base for calculating losses in similar rotors.
Access status: Open Access ,
Fatigue resistance of magnesium alloy AZ 91D at high-frequency cyclic loading
(Wydawnictwa AGH, 2005) Bella, Vladimír; Wolny, Stanisław; Dzik, Stanisław
The presented paper brings the results of Mg-alloy AZ 91D fatigue crack propagation and life measured under high frequency cyclic loading (frequency f = 20 kHz, temperature t = 20±10 Celsius degrees, alternating, symmetric tension-pressure, loading cycle asymmetry R = ±1) in the field of high number of cyclic from N = 6·10(5) cycles to N = 1·10(9) cycles.
Access status: Open Access ,
Identyfikacja pęknięcia belek na podstawie pomiarów amplitud drgań wymuszonych
(Wydawnictwa AGH, 2005) Majkut, Leszek
This paper deals with detection of the location and size of a transverse crack in beam like structure. An input quantity for identification a forced vibration amplitudes was chosen. For this quantity the inverse beam model was created. Identification algorithm based on this model was proposed.
Access status: Open Access ,
Calculation of rotor work on the basis of thermoanemometric measurement results. Part 1
(Wydawnictwa AGH, 2005) Fortuna, Stanisław
Article consists of two parts. The first part depicts results of calculations useful for the rotor work determination on the basis of thermoanemometric measurements and measurements of total pressure impact in given sections of the arrangement. Both measurements were made for one point of characteristic in the vicinity of optimal point, but for five different velocities of the rotor. The aim of the article was to verify both measurement methods and adjust results to the same conditions of flow.
Access status: Open Access ,
Podnoszenie oleju w wirującym cylindrze w aspekcie smarowania górnych łożysk
(Wydawnictwa AGH, 2005) Siemek, Jakub; Salwiński, Józef; Łuczyński, Stanisław; Lepiarczyk, Dariusz
Failure-free operation of mechanisms with shafts situated in varians positions, in this number reducing gears, motoreducers and compressors depends on the method of bearings lubrication and cooling. Solution of that problem is of high importance for proper operation of reducing gears. The problem is significantly more complex for gears with vertical position of shafts. The simple bath lubrication is poorly efficient. Known technological solutions are based on special pumps to force the oil circulaton or external lubrication systems are used for this aim. One of methods to solve this problem is the rotorless pump embedded into the shaft. This design has been developed in the Department of Machine Design and Terotechnology in the AGH University Science and Technology. The behaviour of oil been observed in the rotating cylinder and it was stated that centrifugal forces cause convection of oil particles along the internal surface of the cylinder. The new lubrication system has to provoke continuous flow of oil the gear is filled, up to the upper bearings then to the area of teeth cooperation. The model of oil convection in the cylindrical chamber made in the shaft has been developed to describe the oil convection height in the new self-lubricating system. Mathematical relations have been formulated for determination the basic dimensions and parameters of the new system. The model and bench tests of this system are presented with application of mineral oils VG46 used in lubrication of the light, medium and heavy loaded toothed gears. The results of tests confirm that the new self-lubrication oil system efficiently lubricates the upper bearings of toothed gear with vertical shafts. Oil transported in this way may be also used for the gear mesh lubrication.
Access status: Open Access ,
Pitch-plane models of MR vehicle suspension for experimental testing
(Wydawnictwa AGH, 2005) Martynowicz, Paweł; Sapiński, Bogdan
The study concerns 2 DOF and 3 DOF pitch-plane models of a semi-active vehicle suspension comprising magnetorheological (MR) dampers. The 2 DOF pitch-plane model with two independent spring - MR damper suspension sets enables us to study bounce and pitch motions of the suspended body. The 3 DOF pitch-plane model takes into account also a model of driver's seat and for this reason the third spring - MR damper suspension set was introduced. The mechanical structure, data acquisition and control equipment of the 2 DOF and 3 DOF system configurations are reviewed. Finally, selected results of functional testing conducted in the presented setups are provided.
Access status: Open Access ,
Linearized characterization of a magnetorheological fluid damper
(Wydawnictwa AGH, 2005) Sapiński, Bogdan
The paper is concerned with linearized characterization of a magnetorheological fluid (MR) damper. Two basic damping models, the equivalent viscous damping and the complex modulus, were used to linearize MR damper behaviour. The relationships between the parameters of the damping models were investigated experimentally in terms of the current applied to the damper coil and the maximal piston velocity.
Access status: Open Access ,
Wibroizolowany przejazd samochodowy
(Wydawnictwa AGH, 2005) Targosz, Jan Zdzisław
In the article we analyze the problem of elements of railways and car road at their crossings. The work raises issues critical from the perspective of designing and building driveways at the crossings of car and rail transport. Transport of this kind is inherently accompanied by the dynamic effect on the surroundings. Especially at the moment of entering and leaving the crossing due to the kinetic energy accumulated in it (highly exceeding the usual amount of kinetic energy accompanying the «normal» journey i.e. on the road), there is a prolonged transmission of a vibrating wave through soils onto the engineering structures. The resulting strong vibrations may lead to disaster, damage of the foundations of the buildings nearby or other constructions. On the basis of the analysis of the discrete-linear equation we presented a new concept of vibroisolated solution, a passage at the crossings of car transport roads, a simulation of the dynamics of crossing vehicles and its results on the basis of MSC VisualNostron4D System and its possible usage on given crossings. As the result of the research two applications to the Patent Office were created, which are presented in the literature.
Access status: Open Access ,
Dynamics of active biomechanical models of seated human body and their vibration isolation systems
(Wydawnictwa AGH, 2005) Książek, Marek A.; Janik, Artur
In the paper the dynamic behaviour of the systems composed of active human body models (AHBM) and passive isolation systems (VIS) subjected to sinusoidal and random excitations was discussed. The two active human body biomechanical models («back-off» and «back-on») obtained several years ago by the first author of the presented paper can be considered as active, linear, stable, lumped parameter and unidirectional dynamical systems. These models «seated» on passive vibration isolation systems (VIS) make new, coupled dynamical models (AHBM+VIS). In the first part of the presented paper the dynamical characteristics of the coupled, linear models (AHBM+VIS) were thoroughly analyzed. The new maps of poles distribution of characteristic equations of the systems composed of the coupled models show, that in some cases, these systems can be unstable. In the paper the stability areas were numerically estimated and graphically presented for the simplest, linear vibration isolation system. In the second part of the paper the influence of some chosen nonlinear elements injected into VIS on the amplitudes of chosen model mass accelerations and relative displacements between them was estimated, basing on the results obtained from the simulation approach. The simulation investigations were done for a sequence of time delay of the VIS reactions and sinusoidal excitations. The sinusoidal excitations had variable amplitudes and the frequencies corresponding to the first resonant frequency of the considered AHBM+ VIS systems. The values of the corresponding amplitudes of output signals were compared. In chosen cases where the simulations were done for the random excitations the root mean square values of the output signals were compared. The obtained results were compared with the simplest linear VIS, graphically presented and discussed.
Access status: Open Access ,
Diagnosing elements of propulsion plant of naval vessels by means of vibration measurement
(Wydawnictwa AGH, 2005) Charchalis, Adam; Ćwilewicz, Romuald; Grządziela, Andrzej
The application of vibro-acoustic analysis methods in naval technology has been presented in the paper. This element of Base Diagnosing System (BDS) is accepted and used in the ships, which are powered by the COGAG power plant. The paper presents investigations of permissible in-service unbalance and appropriate assemblage of turbine rotors on the basis of selected vibroacoustic parameters, and finally determination of their permissible operation time resources. Another element of BDS is vibration control of misalignment of propulsion shafts. The described conception concerns evaluative process of the centring state in a transmission shafts within powered, marine gas turbine system as a function of ships displacement. Some structural components of the gas turbine unit and reduction gearbox have been selected for the analysis. Some results of the vibro-tests have been presented as well. All tests had been worked out during sea trials. This described idea is based on the researches of the corvettes' 1241 type power plants.
Access status: Open Access ,
Plastic deformation of metal by pulsation forming
(Wydawnictwa AGH, 2005) Kvačkaj, Tibor; Sokolová, Lucia; Vlado, Martin; Vrchovinský, Vladimir
Pulsation forming of metallic materials (also referred to as stresscycling) is a novel forging method based on the application of a variable pulsation frequency during the metal forming process. This paper presents some new results obtained after pulsation forming of steel grade Cr18Ni1O. The experimental works suggested that the value of summary deformation of 25% (at the pulsation frequency of 30 Hz) was obtained with the very good compromise of yield strength $(R_{p0,2})$, tensile strength $(R_{m})$, elongation $(A_{5})$ and contraction (Z). The results were given with respect to the effect of deformation temperature (from 850 to 920 Celsius degrees) and deformation time (from 2 to 10 sec.) at constant heating temperature (11OOCelsius degrees), constant pulsation frequency (30 Hz) and variant frequency from 10 Hz to 40 Hz on mechanical characteristic $(R_{p0,2}; \; R_{m}; \; A_{5}; \; Z)$ of stainless steel grade Cr18Ni1O.
Access status: Open Access ,
Analiza współpracy sprężarek recyrkulacyjnych z instalacją syntezy amoniaku
(Wydawnictwa AGH, 2005) Worsztynowicz, Barbara
Analysis of work of high-pressure installation of ammonia synthesis enabled a conclusion about the appearance of unstationary wave courses in the pipes pressing synthesis mixture into the column with catalytic deposit. The phenomena appeared when one of recirculation compressors was turned on. To analyse the system of pipelines and the way of their attachement to basic and recirculation compressors some points were selected to observe synchronic course of rapid changing pressures. The research, in which the wave courses took place, was a ground to identify places of local resonance which were a cause of suction parameters devaluation. It had a negative influence upon the compressor efficiency and also resulted in resonance vibrations of the installation.
Access status: Open Access ,
Projekt hybrydowej elektrowni słoneczno-wiatrowej
(Wydawnictwa AGH, 2005) Sitarz, Sławomir
In report one introduced project of power station using simultaneously energy of two sources: of suns and of wind. In phase of project-power station, one qualified local individual supplies of energy kinetic wind and ra-diations of suns. At help of egzergy analysis one qualified this part of supplies, which can be used by receivers connected to projected power station. Analysis egzergy of supplies of energy one effected basing on efficiency of devices executing of conversion and of accumulation of energy. On base of acquaintance of supplies of energy from two sources, of results of analysis egzergy and founded of production of energy, one qualified dimensions of rotors, of turbines wind and active area fotovoltanic.
Access status: Open Access ,
Optimal reduction of vibrations of a one- or two-axis gyroscopic platform on board of a flying object
(Wydawnictwa AGH, 2005) Koruba, Zbigniew; Styczeń, Jerzy
The paper presents a method of optimal reduction of vibrations of a one-or two-axis gyroscopic platform mounted on board of a flying object. The included algorithm allows one to select optimal parameters of the platform as well as optimal coefficients of the controller, and, in consequence, minimise the deviations from the preset motion. The investigations focused on the platform operation affected by short-duration external disturbances, manoeuvres of the aerial vehicle, and dry or viscous friction in the bearings.
Access status: Open Access ,
Trzydziesta rocznica śmierci profesora Władysława Bogusza
(Wydawnictwa AGH, 2005) Engel, Zbigniew
Access status: Open Access ,
Calculation of rotor work on the basis of thermoanemometric measurement results. Part 2
(Wydawnictwa AGH, 2005) Fortuna, Stanisław
In the second part of the article the correction of the balance method has been made by reduction of parameters to those sections where measurements of airflow velocity and the work determination were done. As losses of energy in supply line rotor between measure section and inlet as well as losses of energy in consequence of slot bypass leakage were taken into consideration, both methods of measurements gave the same increases of energy in the rim of rotor. Therefore, the methods may be considered as equivalent. The methods of field velocities and turbulence coefficient averaging were analysed with the aim to develop optimal measurement conditions.