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Wyniki wyszukiwania dla: IMPACT DAMPING
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Effective Formula for Impact Damping Ratio for Simulation of Earthquake-induced Structural Pounding
PublikacjaStructural pounding during earthquakes may cause substantial damage to colliding structures. The phenomenon is numerically studied using different models of collisions. The aim of the present paper is to propose an effective formula for the impact damping ratio, as a parameter of the impact force model used to study different problems of structural pounding under seismic excitations. Its accuracy has been verified by four various...
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Analytical expression between the impact damping ratio and the coefficient of restitution in the non-linear viscoelastic model of structural pounding
PublikacjaWyniki wcześniejszych badań pokazują, iż nieliniowy model lepko-sprężysty zderzeń konstrukcji budowlanych podczas trzęsień ziemi najdokładniej symuluje siłę zderzenia w czasie kontaktu oraz odpowiedź konstrukcji. Celem niniejszego artykułu jest wyprowadzenie wzoru na zależność pomiędzy liczbą tłumienia zderzenia (parametr wspomnianego modelu) a współczynnikiem odbicia, który jest parametrem często stosowanym i analizowanym w literaturze....
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The impact of wind farms with fixed speed induction generators on grid damping in Northern Ireland
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Pelvic vertical shear fractures: The damping properties of ligaments depending on the velocity of vertical impact load
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Ship roll damping moments
PublikacjaWprowadzono nieliniową formę współczynnika tłumienia kołysań bocznych statku oraz jego ekwiwalentną liniową formę. Zastępczy liniowy współczynnik tłumienia może być określony na podstawie kołysań. Przedstawiono przykładowe wyniki nieliniowego współczynnika tłumienia dla promu pasażerskiego "Polonia".
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Approximation of the non-linear roll damping
PublikacjaArtykuł omawia, jak otrzymać oszacowanie nieliniowego momentu tłumiącehgo kołysania boczne okretu za pomocą zapisu przebiegu kołysań swobodnych modelu okrętu. Udowadnia, że 1) moment tłumiący w kategoriach aproksymacji jest nieanalityczną funkcją nieparzystą prędkosci kołysań, 2) standardowa metoda, oparta na stosunku dwóch kolejnych amplitud, ma ograniczone zastosowanie, do niezbyt dużych amplitud kołysań. Zaproponowano nową metodą...
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Investigating lubricants behaviour in microgravity for vibration damping purposes
PublikacjaVibration 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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Wave damping and smoothing in the unsteady pipe flow
Publikacjalaboratoryjne eksperymenty wykonane dla rur polietylenowych o różnej długości wykazały obecność takich zjawisk jak zmienna prędkość propagującej fali ciśnienia oraz jej intensywne tłumienie i wygładzanie. w artykule zaproponowano modyfikacje standardowych równań przepływu nieustalonego. polega ona na wprowadzeniu zmiennej prędkości fali oraz dyssypacji energii na jej czole opisanej członem dyfuzyjnym. do rozwiązania równań zaproponowano...
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Non-linear model of high damping rubber bearing.
PublikacjaCelem artykułu jest analiza modelu łożyska wykonanego z wysokotłumiącej gumy, które wykorzystywane są do posadowienia konstrukcji budowlanych na terenach sejsmicznych. Model umożliwia numeryczną symulację pracy urządzenia pod zadanym obciążeniem i w danych warunkach termiczno-wilgotnościowych. Wyniki analizy pokazują, iż proponowany model umożliwia symulację zachowania się łożyska w szerokim zakresie odkształceń.
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Active Damping of Impulse-Excited Flexible Plate Vibration
PublikacjaArtykuł 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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Propagation of elestic waves in beams including damping effects.
PublikacjaW pracy przedstawiono wyniki analizy propagacji fali sprężystej w belce z tłumieniem wiskotycznym.
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Viscous versus electromagnetic damping – amplification in a neighbourhood of a mechanism singular position
PublikacjaIn the paper, damping of vibrations are considered and compared in a mechanical and in a electromechanical system. In the system, a continuous beam is considered as the main vibrating element. The compared dissipations methods are based on: viscous dampers and DC generators. To increase the possible damping effectiveness, velocity amplification is proposed, i.e., a mechanism is introduced between the beam and the damping element....
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Fabrication and Characterization of Green Polyurethane Foams with Enhanced Vibration Damping Capability
PublikacjaOver the past decades, there has been an intensive development of the technologies and innovations aimed at increasing the quality of life. This development largely concerns the comfort of use of everyday products that, among others, are products of the automotive, construction, or furniture industries. Considering the increase in the comfort of using products such as cars, houses, and flats, one of the comfort features of their...
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Possibilities of using SVC compensators for synchronous generators rotors oscillations damping.
PublikacjaThe article presents the idea of using static var compensators (SVC) for damping generators rotors oscillations. A novel SVC controller structure is proposed to provide better dynamic performance of the power system. A tests results are shown for proposed controller structure, that was carried out in a three-machine power system model as well as in multi-machine model of Polish Power System.
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Nonlinear rate dependent model of high damping rubber bearing.
PublikacjaCelem artykułu jest analiza nieliniowego modelu łożyska wykonanego z wysokotłumiącej gumy, który symuluje pracę urządzenia pod zadanym obciążeniem. Parametry modelu dobrane są na podstawie wyników badań eksperymentalnych. Wyniki pracy pokazują, iż analizowany model umożliwia symulację zachowania się łożyska w szerokim zakresie odkształceń
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Transient response of oscillated carbon nanotubes with an internal and external damping
PublikacjaThe present works aims at modeling a viscoelastic nanobeam with simple boundary conditions at the two ends with the introduction of the Kelvin-Voigt viscoelasticity in a nonlocal strain gradient theory. The nanobeam lies on the visco-Pasternak matrix in which three characteristic parameters have a prominent role. A refined Timoshenko beam theory is here applied, which is only based on one unknown variable, in accordance with the...
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Modal modification of structural damping applied to increase the stability and convergence of numerical integration
PublikacjaThe presented paper refers to numerical tests done on systems fused of multibody and finite-element parts. The appearance of its multibody part gives rise to significant nonlinear components, i.e., second-order nonlinear differential equations express the dynamics. We usually solve these equations by “step-by-step” integration methods. When using the currently available integration algorithms, we approximate these initial systems...
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Investigation the effect of canted rudder on the roll damping of a twin-rudder ship
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Stabilization of the titanium vibration damping wires in the steam turbine blades system
PublikacjaPrzedstawiono metody stabilizacji drutów tłumiących w systemie łopatkowym turbin parowych. Na podstawie badań eksperymentalnych mikrostruktury i własności mechanicznych wykazano przydatność metody stabilizacji na gorąco drutów tłumiących wykonywanych ze stopu tytanu WT3-1.
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Vertical motions damping model test of a lifeboat lowered onto a flat sea surface
PublikacjaThe article presents the experiment’s results of the lifeboat model lowered with an initial speed and then released to fall onto a flat water surface. The purpose of the research is to determine the trajectory of the vertical boat motion and describe it with a mathematical model. This is closely related to determining the damping factor since the vertical motion is damped and the lifeboat gets balanced and stops moving after some...
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Identification of inertia, damping and stiffness parameters for low pressure steam turbine framework.
PublikacjaW pracy przedstawiono metodę identyfikacji masy tłumienia i sztywności kadłuba części niskoprężnej turbiny parowej 200MW.
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Damping Amplification Caused by a Mechanism that Trans-pass Trough its singular Position
PublikacjaW artykule przedstawiono badania dotyczące drgania hybrydowego systemu składającego się z mechanizmu i układu ciągłego. Pomimo ich obecności w wielu codziennych doświadczeniach to w większości przypadków technicznych obecność drgań jest niepożądana. Jednym z podstawowych problemów jest tu długie utrzymywanie się i konieczność tłumienia drgań o niskiej częstotliwości. W artykule badana jest metoda tłumienia oparta na niewspółmierności...
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Dissipated energy minimization in a combustion engine Mount system by position dependent damping coefficients
PublikacjaPraca opisuje rozważania na temat możliwości tłumienia drgań spalinowego silnika czterosuwowego. Do modelowania wykorzystano zasady dynamiki układów wielomasowych. Przedstawiono krótki opis wspomnianego sposobu modelowani. Zbudowano model numeryczny silnika. Model poddano analizie numerycznej. Podczas analizy dynamiki układu skoncentrowano się na elementach tłumiących drgania, obecnych w zawieszeniu silnika oraz na analizie wpływu...
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Numerical Comparison of Damping Amplification Effects Obtained in Neighborhood of a Mechanism Singular Position - Viscous and Electromagnetic Cases
PublikacjaIn the paper, results of numerical investigations are presented. A continuous beam is considered as the main vibrating element. Two energy dissipations methods are compared: viscous dampers and DC generators. To increase the damping effectiveness, velocity amplification is proposed, i.e., a mechanism is introduced between the beam and the damping element, and the mechanism configuration is set as closed to the singular position...
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Span's low damped vibrations and vibration's damping by modal disparity inducted by cable stays temporal addition
PublikacjaW pracy przedstawiono problem obecności słabo tłumionych drgań przęseł mostów wraz z metodą ich aktywnego tłumienia. Badania przeprowadzono korzystając z analizy numerycznej. Analizowany mechanizm zamodelowano korzystając z metody elementów skończonych. W praco przedstawiono zwarty opis wykorzystanej metody. Następnie, zbudowano dwa alternatywne modele, różniące się liczbą odciągów usztywniających przęsło. Wyznaczono postaci i...
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Mechanisms positioned in a neighbourhood of their singular positions - velocity amplification in the electromagnetic damping. Part 2. Numerical Verification
PublikacjaPraca prezentuje zagadnienia występujące podczas elektromagnetycznego tłumienia drgań układów mechanicznych. Analizowano zachowania układu ciągłego i jego drgania. Aby przyśpieszyć tłumienie, wprowadzono specjalny dwuramienny mechanizm umieszczony pomiędzy elementem drgającym i elementem tłumiącym drgania. Mechanizm ustawiony jest w pobliżu swojego ustawienia osobliwego. Aby określić potencjalny kierunek zmian prowadzący do poprawić...
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Identification of dynamic parameters in the context of diagnostics of steel tank with different level of liquid.
PublikacjaThe paper presents an experimental study to identify the dynamic parameters of a water-filled tank model. The experimental modal analysis approach involving the excitation at one point of the structure and acquisition of vibra tions at selected points distri buted over the tank surface allowed to determine the resonance frequencies, mode shapes and damping ratios. The main aim of the research was to examine the influence of...
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Modified linear viscoelastic model of earthquake-induced structural pounding
PublikacjaIn recent times, earthquake-induced structural pounding has been intensively studied through the use of different impact force models. The numerical results obtained from the previous studies indicate that the linear viscoelastic model is relatively simple and accurate in modeling pounding-involved behavior of structures during earthquakes. The only shortcoming of the model is a negative value of the pounding force occurring just...
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Determination of Peak Impact Force for Buildings Exposed to Structural Pounding during Earthquakes
PublikacjaStructural pounding between adjacent, insufficiently separated buildings, or bridge segments, has been repeatedly observed during seismic excitations. Such earthquake-induced collisions may cause severe structural damage or even lead to the collapse of colliding structures. The aim of the present paper was to show the results of the study focused on determination of peak impact forces during collisions between buildings exposed...
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Mechanisms positioned in a neighbourhood of their singular positions - velocity amplification in the electromagnetic damping. Part 1 - Background of the mechanical structure modeling
PublikacjaW pracy przedstawiono metodę modelowania dynamiki drgającego hybrydowego układu mechanicznego złożonego z odkształcalnego podukładu ciągłego oraz z połączonego z nim mechanizmu. U układzie pojawiają się drgania części odkształcalnej. By je wytłumić, ich energia zamieniana jest w energię elektryczną (za pomocą prądnicy prądu stałego) i rozpraszana na oporności obecnej w układzie elektrycznym. Aby przyśpieszyć tłumienie, wprowadzony...
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Numerical study on pounding between two adjacent buildings under earthquake excitation
PublikacjaSeismic excitation, which results in large horizontal relative displacements, may cause collisions between two adjacent structures due to insufficient separation distance between them. Such collisions, known as earthquake-induced structural pounding, may induce severe damages. In this paper, the case of pounding between two adjacent buildings is studied by the application of single degree-of-freedom structural models. Impact is...
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Dynamics analysis of footbridge mode shapes the s8 expressway on the basis of the results of in situ tests
PublikacjaNon-destructive diagnostics for structure may use dynamic measurements realized during vibrations of a facility induced by dynamic environmental impact, enforced by the use of inductors or impulse impact. Dynamic tests and the analysis were undertaken for a footbridge situated over the expressway S8. The studies in situ allowed for dynamic characteristics to be determined: frequency, shape modes and damping for respective frequency...
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Effect of soil on the capacity of viscous dampers between adjacent buildings
PublikacjaThis study investigated the seismic pounding of two adjacent buildings considering soil–structure interaction (SSI). A comprehensive parametric study of buildings with different heights was performed to reveal the pounding-involved behaviour considering the soil effect. Wavelet transform has been conducted to gain insight into the differences in the frequency contents of the impact forces between fixed- and flexible-base adjacent...
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The Impact of Hybrid Flame Retardant Compositions on the Performance of Foamed Flexible Polyurethane/Ground Tire Rubber Composites
PublikacjaCurrent sustainability-oriented trends affect polyurethane (PU) materials and stimulate the incorporation of recycled or waste-based materials as fillers. Ground tire rubber (GTR) poses as an auspicious candidate due to the excellent performance of car tires. Despite the benefits related to the mechanical performance, it contributes to the increasing flammability of the resulting composites. Herein, presented work assessed the...
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Modal Adjustment of Rayleigh Based Structural Damping and Coordinate-Partitioning Algorithm Dedicated to Frictionless Contact Constraints between Multibody System and Structure Modelled with Finite Elements
PublikacjaThe paper presents a dedicated numerical algorithm. The algorithm is advantageous during investigations of the dynamics of a hybrid multibody / finite-elements system. We focus our attention on interactions resulting from mechanical contact. Pointwise contact connects a vertex of the multibody structure and a surface of the elastic reference body. Instead of a positive value of the relative penetration factor, constraint equations...
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Experimental study on models of cylindrical steel tanks under mining tremors and moderate earthquakes
PublikacjaThe aim of the study is to show the results of complex shaking table experimental investigation focused on the response of two models of cylindrical steel tanks under mining tremors and moderate earthquakes, including the aspects of diagnosis of structural damage. Firstly, the impact and the sweep-sine tests have been carried out, so as to determine the dynamic properties of models filled with different levels of liquid. Then,...
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The propagation of the waves in the CTO S.A. towing tank
PublikacjaThe paper presents the results of research focused on the wave propagation in the CTO S.A. deepwater towing tank. In the scope of paper, the wavemaker transfer function was determined for regular waves, based on the Biésel Transfer Function and further for irregular waves, based on Hasselman model of nonlinear energy transfer. The phenomena: wave damping, wave breakdown and wave reflection, were measured, analyzed and mathematically...
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Impacts in case of triple unilaterally constrained system
PublikacjaThe this paper focus on the behaviour of a “rigid” body biting into another “rigid” body, with some nonzero relative velocity. In the presently considered case, the introduced collision appears between a selected element of a multibody structure and its reference body being interpreted as the motionless ground. Instead of the classic case, described in a number of dissertations, where a single impacting contact is considered, three...
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Linear viscoelastic modelling of damage-involved structural pounding during earthquakes
PublikacjaDamage-involved structural pounding during earthquakes has been recently intensively studied using different impact force models. The results of the previous studies indicate that the linear viscoelastic model is relatively simple yet accurate in modelling pounding-involved behaviour of structures during earthquakes. The only shortcoming of the model is a negative value of the pounding force occurring just before separation, which...
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Relations between magnetosonic perturbations as an indicator of a magnetosonic exciter and equilibrium parameters of a plasma
PublikacjaThe thermodynamic relations between perturbation of pressure and pertur- bation of mass density and between components of velocity which specify a magnetosonic wave are theoretically studied. A planar flow with the wave vec- tor forming a constant angle with the equilibrium magnetic field is investigated. The theory considers deviation from the adiabaticity of a flow due to some kind of heating–cooling function and thermal conduction...
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The experimental identification of the dynamic coefficients of two hydrodynamic journal bearings operating at constant rotational speed and under nonlinear conditions.
PublikacjaHydrodynamic bearings are commonly used in ship propulsion systems. Typically, they are calculated using numerical or experimental methods. This paper presents an experimental study through which it has been possible to estimate 24 dynamic coefficients of two hydrodynamic slide bearings operating under nonlinear conditions. During the investigation, bearing mass coefficients are identified by means of a newly developed algorithm....
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Identification of ship’s hull mathematical model with numerical methods
PublikacjaThe modern maritime industry is moving toward the development of technology that will allow for full or partial autonomy of ship operation. This innovation places high demands on ship performance prediction techniques at the design stage. The researchwork presented in the article is related to the design stage of the ship and concerns methods for prognosis and evaluation of the specific operational condition of the ship, namely...
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Analysis of Ferroresonance Mitigation Effectiveness in Auxiliary Power Systems of High-Voltage Substations
PublikacjaFerroresonance in power networks is a dangerous phenomenon, which may result in overcurrents and overvoltages, causing damage to power equipment and the faulty operation of protection systems. For this reason, the possibility of the occurrence of ferroresonance has to be identified, and adequate methods need to be incorporated to eliminate or reduce its effects. The aim of this paper is to evaluate the effectiveness of ferroresonance...
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Experimental Study on the Effectiveness of Polyurethane Flexible Adhesive in Reduction of Structural Vibrations
PublikacjaThe 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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HYBRID REDUCED MODEL OF ROTOR
PublikacjaIn the paper, the authors describe the method of model reduction of a rotor system. The proposed approach enables to obtain a low order model including e.g. nonproportional damping or the gyroscopic effect. This method is illustrated using the example of a rotor system. First, a model of the system was built without gyroscopic and damping effects by using the rigid finite element method. Next, this model was reduced. Finally, two...
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The effectiveness of polymer adhesive in reduction of vibrations of structural members
PublikacjaIn this paper, the idea of using polymer adhesive as a damping layer is proposed. An experimental study of two aluminium cantilevered beams has been conducted. One of them presents a plain cantilevered beam, while the second one considers two aluminium beams bonded with a polymer adhesive of different thickness (0,5; 1,2; 1,75; 3,1 and 5 mm). The polymer adhesive considered in the study is a specially designed flexible...
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Hybrid model of geared rotor system
PublikacjaIn the paper a hybrid model of a geared multirotor system has been developed. The model is obtained by application of both the modal decomposition methodology and the spatial discretization method. Reduced modal model was constructed for the system without gyroscopic and damping effects. The gyroscopic interaction, damping and other phenomena which are difficult to include in the modal approach were modeled by application of simply...
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Experimental and numerical analysis of an aluminum cantilevered beam with polymer adhesive
PublikacjaIn this paper, experimental and numerical investigation on a composite cantilevered aluminum beam has been conducted. The subject of the study consists of two plain aluminum elements bonded with polymer adhesive of different thickness. It has been proven in the previous study that this kind of material has high damping properties. During an experimental investigation, value of damping ratios have been obtained. The aim of a numerical...
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Enhancing the Seismic Resistance of Columns by GFRP Confinement Using Flexible Adhesive-Experimental Study
PublikacjaIn this paper, the results of two experiments, focused on testing the effectiveness of a method of enhancing the seismic (dynamic) resistance of masonry columns with the use of flexible polymer adhesive, are shown. The first experiment was devoted to investigate the damping properties of a polymer working between two stiff layers, whereas the aim of the second one was to verify if the identified damping properties of the polymer...
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Polymeric Bearings as a new base isolation system suitable for mitigating machine-induced vibrations
PublikacjaThe present paper summarizes the preliminary results of the experimental shaking table investigation conducted in order to verify the effectiveness of a new base isolation system consisting of Polymeric Bearings in reducing strong horizontal machine-induced vibrations. Polymeric Bearing considered in the present study is a prototype base isolation system, which was constructed with the use of a specially prepared flexible polymer...