Search results for: blade vibrations
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Geometrical conditions of saw blade`s entering into and going out of material during wood cutting
PublicationW pracy przedstawiono analizę geometrycznych warunków wejścia i wyjścia ostrza piły z materiału obrabianego przy przecinaniu drewna. Przedstawiono czasowy i przestrzenny rozkład geometrycznych parametrów wejścia i wyjścia ostrza i ich wpływ na trwałość ostrzy i dokładność przecinania.
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The Application of Fluidic Sealing in Shrouded Gas Turbine Blades
PublicationThis paper presents a study conducted on a new gas turbine designed to limit leakage in the labyrinth seal. The slots in the fin are used to generate a bypass flow, which obstructs the flow in the gap above the fin. The method was tested numerically and experimentally beforehand using a simplified model without rotation or blade passages. In this paper, the validation of the method using a model of a turbine stage is shown. Reynolds-averaged...
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THE VIBRATION BASED DIAGNOSTICS OF SHIP PROPULSION SYSTEMS
PublicationThe article has been worked out on the basis of the report devoted to the conducted diagnostic investigations of the ship main propulsion unit’s mechanical system. Gdansk University of Technology has been ordered with such investigations by the repair Shipyard carrying out the ship’s overhaul. Diagnostic tests involved measurements and analyses of the vibration signals generated in selected constructional kinematic pairs of the...
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VIBRATION DIAGNOSTICS OF FOOTBRIDGE WITH USE OF ROTATION SENSOR
PublicationThe benefits of the additional measurement of rotational degrees of free-dom on the performance of the vibration diagnosis of bridges are studied in this paper. The common vibrational diagnostics that uses translational degrees of freedom is extended by measurements of rotations. The study is curried out on a footbridge and the presence of damage as well as its location and size is determined with use of FEM updating procedure....
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Analog modelling in qualitative analysis of vibration propagation
PublicationThe theory of dynamic systems is usually used to model the real systems. The models are based on solving ordinary differential equations, partial or difference, which enable obtaining the relation between input signal and the system response (output signal). The analogy between those models and generalized dynamic systems or control systems can be practically used. Vibration propagation can be described in a similar way as the...
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Sounding rocket vibration mechanical filter and amplifier
PublicationMeasuring accelerations and vibrations of a sounding rocket provides both information for engineers on the launcher vehicle performance as well as environment description for future payload designers. Typically, information on the level of vibration and eigenfrequencies are required to properly design a payload. This paper presents a design of a novel mechanical filter and amplifier for mechanical vibrations. Its key feature is...
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On the geometrically nonlinear vibration of a piezo-flexomagnetic nanotube
PublicationIn order to describe the behavior of thin elements used in MEMS and NEMS, it is essential to study a nonlinear free vibration of nanotubes under complicated external fields such as magnetic environment. In this regard, the magnetic force applied to the conductive nanotube with piezo-flexomagnetic elastic wall is considered. By the inclusion of Euler-Bernoulli beam and using Hamilton’s principle, the equations governing the system...
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Vibration surveillance of dynamic systems and production processes
PublicationPraca dotyczy poszukiwania sposobów minimalizacji poziomu drgań podczas pracy maszyn i urządzeń wykonujących określone procesy robocze. Do modelowania dyskretnego wykorzystano metodę elementów skończonych. Rozważano dynamikę niestacjonarnego dyskretnego układu sterowanego, którego zachowanie opisano we współrzędnych uogólnionych, jak również - układu hybrydowego. Ten ostatni uzyskano dzięki wyodrębnieniu z całości podukładu stacjonarnego,...
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Eulerian motion magnification applied to structural health monitoring of wind turbines
PublicationSeveral types of defects may occur in wind turbines, as physical damage of blades or gearbox malfunction. A wind farm monitoring and damage prediction system is built to observe abnormal vibrations of elements of wind turbine: blades, nacelle, and tower. Contactless methods are developed which do not require turbine stopping. In this work, structural health monitoring of a wind turbine is evaluated using a conversion from the captured...
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Updating Finite Element Model of a Wind Turbine Blade Section Using Experimental Modal Analysis Results
PublicationThis paper presents selected results and aspects of themultidisciplinary and interdisciplinary research oriented for the experimental and numerical study of the structural dynamics of a bend-twist coupled full scale section of awind turbine blade structure.Themain goal of the conducted research is to validate finite elementmodel of themodified wind turbine blade section mounted in the flexible support structure accordingly to the...
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Report on investigation of turbine blade from main engine turbocharger 420.34 from M/V "Nordstraum"
PublicationWykonano badania pęknięcia na łopatce turbiny turbodoładowania silnika głównego. Ustalono, ze przyczyną pęknięcia była korozja międzykrystaliczna.
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JOURNAL OF VIBRATION AND CONTROL
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The influence of selected parameters of idd on vibrations of contact in ac hybrid breaker
PublicationWzrost mocy systemów zasilania na statkach wymaga poszukiwania nowych rozwiązań wyłączników dc oraz ac. Od kilku lat trwają prace nad modelowaniem ultra szybkiego hybrydowego wyłącznika prądu. Czas wyłączenia prądu wyłącznika zależy od wielu parametrów. W pracy przedstawiono wyniki badań eksperymentalnych i symulacyjnych wyłącznika ze szczególnym uwzględnieniem rezystancji zestyku.
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Implementing Simulationx in the Modelling of Marine Shafting Steady State Torsional Vibrations
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Cutting Forces and Vibrations During Ball End Milling of Inclined Surfaces
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Reduction of vibrations of steel structure models with Polymeric Bearings - experimental study
PublicationEarthquake-induced ground motions are the most severe and unpredictable threats to the structures all around the world. Therefore, designing earthquake protective systems has become an extremely challenging problem in civil engineering. Base isolation is one of the most popular and widely adopted methods of protecting structures against earthquake forces. The present paper reports the results obtained from the shaking table experimental...
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Water-mediated influence of a crowded environment on internal vibrations of a protein molecule
PublicationThe influence of crowding on the protein inner dynamics is examined by putting a single protein molecule close to one or two neighboring protein molecules. The presence of additional molecules influences the amplitudes of protein fluctuations. Also, a weak dynamical coupling of collective velocities of surface atoms of proteins separated by a layer of water is detected. The possible mechanisms of these phenomena are described....
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Influence of Traffic-Induced Vibrations on Humans and Residential Building—A Case Study
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Experimental Study on the Effectiveness of Polyurethane Flexible Adhesive in Reduction of Structural Vibrations
PublicationThe aim of the present study is to consider the idea of using polyurethane flexible adhesive in to reduce the vibrations in structures exposed to dynamic loads and evaluate their damping properties in relation to large deformations. Firstly, two aluminium cantilever beams, simulating structural elements (without and with polyurethane layer in the form of tape), were analysed, in order to check the damping of the unconstrained polymer...
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EMPIRICAL ASSESMENT OF THE MAIN DRIVING SYSTEM OF THE CIRCULAR SAWING MACHINE
PublicationThe producers of panel saws tend to improve sawing accuracy and minimise a level of vibrations, to increase their competitiveness at the market. Mechanical vibrations in the main saw driving system, which level depend on a plethora independent factors, may really affect sawing accuracy and general machine tool vibrations. The objective of the research was to explore vibrations signals of the main spindle system, and to extract...
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International Journal of Acoustics and Vibration
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Journal of Vibration Engineering & Technologies
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Romanian Journal of Acoustics and Vibration
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Diagnostic testing of marine propulsion systems with internal combustion engines by means of vibration measurement and results analysis
PublicationIn this paper selected issues concerning vibration diagnosis of the mechanical system within marine propulsion units have been presented, carried out on the basis of experimental examinations of a real object in which an exceedance of the allowable vibration’s level had been observed. Used diagnosing system has been characterised. A procedure of longitudinal and transverse vibrations shaft lines of the mechanical system within...
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Pro-ecological technology of wood sawing with circular saw blades
PublicationW niniejszym artykule opisano możliwości materiało- i energooszczędnego przecinania piłami tarczowymi. Przedstawiono również przykłady efektów zastosowania proekologicznych technologii przecinania w przemyśle.
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Shape Optimisation of Kaplan Turbine Blades Using Genetic Algorithms
PublicationThis monograph is a comprehensive guide to a method of blade profile optimisation for Kaplan-type turbines. This method is based on modelling the interaction between rotor and stator blades. Additionally, the shape of the draft tube is investigated. The influence of the periodic boundary condition vs. full geometry is also discussed. Evolutionary algorithms (EA) are used as an optimisation method together with artificial neural...
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Analysis of radial run-out of circular saw's cutting blades
PublicationW pracy przedstawiono analizę bicia promieniowego ostrzy pił tarczowych w procesie przecinania drewna. Analizę przeprowadzono na podstawie zróżnicowania grubości warstw skrawanych przez poszczególne ostrza piły. Dla przykładowej piły, zaprezentowano wyniki obliczeń przebiegów grubości warstw skrawanych przez poszczególne ostrza i grubości całkowitej warstwy skrawanej dla całej piły.
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Stability evaluation of the marine propulsion unit mechanical system bymeans of vibrations measurements and their analysis.
PublicationIn paper selected issues concerning vibration diagnosis of the mechanical system within marine propulsion units have been given. The analysis of vibration parameters was carried out on the basis of experimental examinations of a real object in which an exceedance of the allowable vibration's level had been observed. In the beginning, the vibration apparatus being on laboratory equipment of the Department of Ship Power Plants of...
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Stability evaluation of the marine propulsion unit's mechanical system by means of vibration measurements and their analysis
PublicationIn this paper selected issues concerning vibration diagnosis of the mechanical system within marine propulsion units have been given. The analysis of vibration parameters was carried out on the basis of experimental examinations of a real object in which an exceedance of the allowable vibration's level had been observed. In the beginning, the vibration apparatus being on laboratory equipment of the Department of Ship Power Plants...
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Active Damping of Impulse-Excited Flexible Plate Vibration
PublicationArtykuł prezentuje metodę aktywnego tłumienia drgań podatnej płytki wzbudzanych impulsowo. Układ sterowania składa się z aktywych wzbudników piezoelektrycznych przymocowanych do przedmiotu. Efektywnośc metody została potwierdzona badaniami eksperymentalnymi.
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Optimum control of the selected vibration forms in mechanical systems
PublicationW artykule przedstawiono zagadnienie optymalnego sterowania wybranymi formami drgań układów mechanicznych. Dla zaprezentowania sposobu i procedury wyznaczania optymalnych nastaw regulatora i współczynników wagowych wskaźnika jakości posłużono się dwoma przykładami liczbowymi. W pierwszym z nich rozważano uproszczony układ mechaniczny składający się z dwóch sztywnych elementów skończonych połączonych za pomocą elementów sprężysto-tłumiących,...
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An adaptation of modal control to vibration control of industrial robots
PublicationRozważania dotyczą drgań niestacjonarnego układu nośnego manipulatora IRb-6. Do nadzorowania drgań zastosowano algorytm sterowania modalnego przy energetycznym wskaźniku jakości. Celem proponowanego algorytmu jest minimalizacja poziomu drgań końcówki manipulatora, co spowoduje zwiększenie obciążeń dopuszczalnych współczesnych linii zrobotyzowanych, jak również poprawę dokładności oraz powtarzalności pozycjonowania robota.
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A mechatronic approach towards vibration surveillance of manipulator robots
PublicationW pracy przedstawiono nadzorowanie drgań niestacjonarnego układu nośnego manipulatora IRb-6 z wykorzystaniem sterowania modalnego przy energetycznym wskaźniku jakości. Celem proponowanego algorytmu jest minimalizacja poziomu drgań końcówki manipulatora, co prowadzi do zwiększenia dopuszczalnych obciążeń współczesnych linii zrobotyzowanych oraz do poprawy dokładności i powtarzalności pozycjonowania robota. Rozważania dotyczą zadanej...
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Investigating lubricants behaviour in microgravity for vibration damping purposes
PublicationVibration is one of the harshest environments an object is exposed to during and after launch into space on a launch vehicle. Such vibrations should be damped to avoid destruction of the spacecraft or its elements. Currently, active and material damping is used. A possibility of using lubrication as the damping factor is suggested by some research. MoS2 is a typical solid lubricant used in space applications. Its properties vary...
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Vibration based damage localization in non-homogeneous structures
PublicationPrzedmiotem badań jest identyfikacja lokalnych uszkodzeń w konstrukcjach budowlanych. Przedstawione są trzy metody bazujące na teorii drgań. Są to metody badające: częstości własne, podatność i krzywizny postaci drgań układu. Skuteczność metod pokazana jest na przykładach symulacji komputerowych, wykonanych dla belki swobodnie podpartej, wspornikowej oraz podwieszonej kładki dla pieszych. Dodatkowo zaprezentowane są wyniki badań...
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Vibration monitoring of structures in the light of the Polish and international requirements
PublicationThe paper concerns the wide range of strategies used to protect structures against man-made dynamic excitation. The most popular approaches applied worldwide are compared, and the main differences and similarities are summarized. The literature studies are supported by the results of the measurements performed on different types of real structures, which are sensitive and insensitive to the dynamic load. To make the conclusions...
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Vibration transpotation of a viscoelastic raw materials in drying process.
PublicationPrzedstawiono zagadnienie transportu wibracyjnego surowca o własnościach lepko-sprężystych w procesie suszenia oraz propozycje rozwiązania technicznego umożliwiającego zastosowanie tego sposobu transportu w urządzeniach produkcyjnych. W rozwiązaniu tym zastosowano panele zawieszone na elementach sprężystych, których drgania sterowane są mikroprocesorowo w układzie sterowania w pętli sprzężenia zwrotnego w celu utrzymania właściwych...
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Vibrational properties and stability of FePt nanoalloys
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Economic migrations to Poland in 2008-2018
PublicationThe aim of the article is to present the stream and structure of economic migrants to Poland between 2008-2018. The first part presents economic migrations in its theoretical aspects, explaining the concept and presenting definitions. Then, the institutional and legal conditions of economic migration to Poland with particular emphasis on documents recquired by Polish labor market were presented i.e. work permits, seasonal work...
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Vibrational excitation of acetylene by positron impact
PublicationVibrationally inelastic quantum calculations are carried out at low collision energies for the scattering of a beam of positrons off acetylene gaseous molecules. The normal mode analysis is assumed to be valid and the relative fluxes into the C–C and C–H symmetric vibrational modes are computed within a Body-Fixed (BF) formulation of the dynamics by solving the relevant vibrational Coupled Channels (VCC) equations. The clear dominance...
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Transient torsional vibrations control in the geared drive trains of the hot rolling mills
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Rigid finite elements and multibody modelling used in estimation and reduction of rod vibrations
PublicationIn the paper, a mechanical set composed of a robot (manipulator) and of an elastic beam is considered. The beam is fixed to the top of the robot structure. In most of the similar cases, undesired vibrations can be excited in the beam. They are especially significant, when dynamics in the robot braking period is examined. In the paper, estimation and modification of length of the braking period is proposed, in order to reduce the...
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The Influence of Tool Wear on the Vibrations During Ball end Milling of Hardened Steel
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Modelling of the Baumann turbine stage operation Part II. Free and kinetic vibrations
PublicationIn this paper has been presented a methodology of validation a novel mathematical model dedicated to evaluation and prediction of material degradation and demage of steam turbine elements such as blades, valves and pipes due to three mechanisms: stress-corosion, high-temperature creep and low-cyclic fatigue. The validation concept is based on an experimental setup manufactured in the Laboratory of Faculty of Mechanical and Power...
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Water-mediated long-range interactions between the internal vibrations of remote proteins
PublicationIt is generally acknowledged that the mobility of protein atoms and the mobility of water molecules in the solvation layer are connected. In this article, we answer the question whether a similar interdependence exists between the motions of atoms of proteins separated by the hydration layers of variable thickness. The system consisted of a kinesin catalytic domain and a tubulin dimer. It was studied using molecular dynamics simulations....
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The application of neural networks in forecasting the influence of traffic-induced vibrations on residential buildings
PublicationTraffic-induced vibrations may cause the cracking of plaster, damage to structural elements and, in extreme cases, may even lead to the structural collapse of residential buildings. The aim of this article is to analyse the effectiveness of a method of forecasting the impact of vibrations on residential buildings using the concept of artificial intelligence. The article presents several alternative forecasting systems for which...
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Minimization of vibrations during milling of flexible structures using mechatronic design techniques
PublicationThe paper presents an innovative effective method of minimizing vibrations during milling of flexible structures, using a new vibration suppression method based on a workpiece holder with adjustable support stiffness. The proposed method is rooted in mechatronic design techniques, which can become a standard procedure for optimizing the milling process.
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An optimal form of the finite element mass matrix in the analysis of longitudinal vibrations of rods
PublicationIn this paper, an attempt is made to find the optimal form of the mass matrix of a rod finite element, which allows one to obtain the smallest errors in the longitudinal frequency determination of natural vibrations of any boundary conditions within the whole range of determined frequencies. It is assumed that the mass matrix can be treated as a linear combination of the consistent and diagonal matrices. Based on analytical considerations,...
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Comparing the Effectiveness of ANNs and SVMs in Forecasting the Impact of Traffic-Induced Vibrations on Building
PublicationTraffic - induced vibrations may cause damage to structural elements and may even lead to structural collapse. The aim of the article is to compare the effectiveness of algorithms in forecasting the impact of vibrations on buildings using the Machine Learning (ML) methods. The paper presents two alternative approaches by using Artificial Neural Networks (ANNs) and Support Vector Machines (SVMs). Factors that may affect traffic-induced...
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Predicting the impact of traffic–induced vibrations on buildings using artificial neural networks
PublicationTraffic–induced vibrations may constitute a considerable load to a building, cause cracking of plaster, cracks in load–bearing elements or even a global structural collapse of the whole structure [1-4]. Vibrations measurements of real structures are costly and laborious, not justified in all cases. The aim of the paper is to create an original algorithm, to predict the negative dynamic impact on the examined residential building...