Dissertations / Theses on the topic 'Elastomeric isolators'
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1
Ardic, Halil. "Design And Modeling Elastomeric Vibration Isolators Using Finite Element Method." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615684/index.pdf.
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In this thesis, a process is developed for designing elastomeric vibration isolators in order to provide vibration isolation for sensitive equipment being used in ROKETSAN A.S.&rsquos products. For this purpose, first of all, similar isolators are examined in the market. After that, appropriate elastomeric materials are selected and their temperature and frequency dependent dynamic properties are experimentally obtained. Parametric finite element model of the isolator is then constituted in ANSYS APDL using the properties of elastomeric materials and the conceptual design of the isolator. Then, according to design requirements, final design parameters of the vibration isolator are determined at the end of design iterations. In the next step, vibration isolator that was designed is manufactured using the elastomeric material chosen, by a local rubber company. Finally, design process is verified by comparing analysis and test results.
2
Fredette, Luke. "Dynamic Analysis of Fractionally-Damped Elastomeric and Hydraulic Vibration Isolators." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1479904009913121.
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3
Ramesh, Ram S. "Identification of Multi-Dimensional Elastic and Dissipation Properties of Elastomeric Vibration Isolators." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515109658022859.
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4
Hedayati, Dezfuli Farshad. "Hysteretic behaviour of steel- and fibre-reinforced elastomeric isolators fitted with superelastic shape memory alloy wire." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/53019.
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Among different types of earthquake protective mechanisms, elastomeric base isolators, also called rubber bearings (RBs), are one of the most well-known systems that are widely used in buildings and bridges. They can regulate the seismic response of structures, increase the public safety, and reduce the cost of repair and rehabilitation by providing lateral flexibility and dissipating the earthquake’s energy. RBs consist of elastomeric layers which are reinforced with steel shims or fibre-reinforced polymer composites. Seeking performance improvements, as well as cost and weight reduction led scientists to introduce different types of RBs. However, most RBs possess weaknesses such as limited shear strain capacity, un-recovered residual deformation, and instability due to large deformations. Using superelastic (ability to regain original shape upon unloading) shape memory alloy (SMA) in the form of wire, bar, or spring is a solution to partially overcome the aforementioned limitations. Its unique characteristics such as a flag-shaped hysteresis with zero residual deformation, superelastic effect (up to 13.5% recoverable strain) and a suitable fatigue property make it an ideal candidate for such applications. Objectives of this thesis are to propose a new generation SMA wire-based RBs (SMA-RB) and develop a novel constitutive model for such smart isolators in order to accurately capture their shear hysteretic behaviour. With the purpose of evaluating the performance of SMA-RBs in structural applications, the seismic fragility of a highway bridge isolated by SMA-RBs was assessed. First, a number of scaled carbon fibre-reinforced elastomeric isolators (C-FREIs) were manufactured and tested. Then, based on the experimental observations, numerical simulations were generated using finite element method (FEM). Results showed that incorporating SMA wires into natural and high-damping rubber bearings (NRB, HDRB) slightly improves the re-centring capability and energy dissipation capacity. However, equipping lead rubber bearing (LRB) with double cross SMA wires significantly reduces the residual deformation and noticeably enhances the energy damping property. It was also depicted that the developed hysteresis of SMA model can be characterized by three stiffnesses and two shear strain limits upon activation of SMA wires. Findings revealed that SMA wires can increase the reliability of elastomeric bearings and bridge system.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
5
Mano, Toshihisa Verfasser], Ingbert [Gutachter] [Mangerig, Akimitsu [Gutachter] Kurita, and Takashi [Gutachter] Yamaguchi. "Numerical and experimental analysis of the load-carrying behaviour of laminated elastomeric bearings as seismic isolators / Toshihisa Mano ; Gutachter: Ingbert Mangerig, Akimitsu Kurita, Takashi Yamaguchi ; Akademischer Betreuer: Ingbert Mangerig ; Universität der Bundeswehr München, Fakultät für Bauingenieurwesen und Umweltwissenschaften." Neubiberg : Universitätsbibliothek der Universität der Bundeswehr München, 2016. http://nbn-resolving.de/urn:nbn:de:bvb:706-4854.
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6
Mano, Toshihisa Verfasser], Ingbert [Gutachter] [Akademischer Betreuer] Mangerig, Akimitsu [Gutachter] [Kurita, and Takashi [Gutachter] Yamaguchi. "Numerical and experimental analysis of the load-carrying behaviour of laminated elastomeric bearings as seismic isolators / Toshihisa Mano ; Gutachter: Ingbert Mangerig, Akimitsu Kurita, Takashi Yamaguchi ; Akademischer Betreuer: Ingbert Mangerig ; Universität der Bundeswehr München, Fakultät für Bauingenieurwesen und Umweltwissenschaften." Neubiberg : Universitätsbibliothek der Universität der Bundeswehr München, 2016. http://d-nb.info/1123038260/34.
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7
Palma, Pietro Maria. "Adeguamento sismico di ponti esistenti mediante l’inserimento di isolatori elastomerici." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
Il presente lavoro è stato organizzato analizzando separatamente due tematiche complementari inerenti la sismica dei ponti a travata continua. In particolare, la prima parte (Parte A) verte sull'adeguamento sismico di ponti esistenti in cui, a partire dalla soluzione tradizione (non adeguata), sono state ricercate soluzioni di adeguamento mediante l’utilizzo dei più diffusi dispositivi di protezione sismica presenti in commercio.
La seconda parte (Parte B), invece, verte sull'applicazione di una metodologia specifica di adeguamento, quella basata sull'utilizzo di isolatori elastomerici, applicata ad un Caso Studio frutto della collaborazione del consorzio ReLUIS con L’Università di Bologna.
8
York, David J. "A novel magnetorheological fluid-elastomer vibration isolator /." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1448335.
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Thesis (M.S.)--University of Nevada, Reno, 2007."August, 2007." Includes bibliographical references (leaves 83-86). Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2007]. 1 microfilm reel ; 35 mm.
9
Adjerid, Khaled. "A Study on the Dynamic Characterization of a Tunable Magneto-Rheological Fluid-Elastic Mount in Squeeze Mode Vibration." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/33628.
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This research undertakes the task of static and dynamic characterization for a squeeze mode Magneto-Rheological (MR) Fluid-Elastic mount. MR fluidâ s variable viscosity rate is advantageously used to develop a mount capable of mitigating input vibrations of varying magnitudes and frequencies depending on electromagnetic flux. Various mechanical components are synthesized into a dynamic testing rig in order to extract vibrational characteristics of the mount and to compare it with existing mount technologies.
This project focuses on a mount design that was proposed and improved upon by previous researchers at the Center for Vehicle Systems and Safety (CVeSS). Using a previously designed electromagnet and test rig, the MR mounts are characterized using a quasi-static test. From this test we extract the stiffness and damping characteristics of the MR mount. A set of upper and lower limit baseline mounts made with rubber and steel inserts are also tested simultaneously with the MR mount. Their isolation improvements are compared with conventional passive mounts.
After acquiring the stiffness and damping characteristics of the mount, a model is used to simulate a response to input vibrations in the frequency domain. A dynamic test is run on both the baseline testers as well as the MR mount. Having the frequency-magnitude response allows us to determine a usable resonance range and magnitude of vibration mitigation. The results of this study indicate that the mounts tested here are an effective means of suppressing start-up vibrations within mechanical systems and show promise for further development and application. Future studies of these systems can include tests of MR metal-elastic mount designs for durability as well as parametric studies based on MR fluid type and other factors.Master of Science
10
Zampini, Niccolò. "Adeguamento sismico di ponti esistenti mediante inserimento di isolatori elastomerici e smorzatori viscosi." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textAbstract:
Il presente lavoro di tesi riguarda lo studio dell’adeguamento sismico di ponti esistenti a travata continua.
La prima parte (Parte A) affronta lo studio dello schema di vincolo tradizionale (non adeguato) dei ponti esistenti per poi formulare, a partire da questo, soluzioni di adeguamento con l’utilizzo di dispositivi di protezione sismica in commercio.
La seconda parte (Parte B), invece, verte sull'applicazione di specifiche soluzioni di adeguamento, al Caso Studio oggetto del progetto di ricerca “Contributi normativi relativi a Isolamento e Dissipazione” della Reluis. È stato dunque studiato il Caso Studio con diverse soluzioni di vincolo le quali prevedono sia l’utilizzo di soli smorzatori fluido-viscosi sia l’utilizzo congiunto di isolatori elastomerici con i suddetti smorzatori. Le analisi sono state svolte sia con modelli FEM sia con modelli semplificati implementati nel software Matlab.
Il presente lavoro è volto a perseguire due macro obiettivi: nella Parte A, a valle della ricerca delle soluzioni di adeguamento sismico attualmente a disposizione, si cerca di fornire ai progettisti, per ogni soluzione di adeguamento trattata, dei modelli semplificati a pochi gradi di libertà (sistemi minimi) rappresentativi, sotto determinate ipotesi, del comportamento dell’impalcato, con lo scopo di creare un supporto ordinato e di facile applicazione progettuale di interventi di miglioramento/adeguamento su ponti esistenti ma utili anche per progettazione ex novo; nella Parte B, applicando al caso studio due particolari soluzioni trattate nella prima parte, si confrontano i risultati fornendo per questo caso studio specifico le soluzioni migliori dal punto di vista di salvaguardia delle sottostrutture, inoltre si cerca di fornire una procedura per la progettazione semplificata per il dimensionamento degli isolatori, accoppiati con gli smorzatori, atta ad ottenere le caratteristiche meccaniche e geometriche da inserire poi nel programma di calcolo utilizzato.
11
Rustichelli, Lorenzo. "Progetto in zona sismica di un edificio in calcestruzzo: confronto tra comportamento a base fissa e comportamento con isolamento alla base." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20300/.
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Il presente lavoro affronta lo studio di una struttura in calcestruzzo ipotetica, situata nella città di Bologna, su cui verrà effettuato un intervento tramite isolatori sismici in modo da migliorare notevolmente il comportamento della struttura sotto azione del sisma.
In particolare verrà studiata in base a tre diverse condizioni:
1) Condizione 1: struttura a base fissa;
2) Condizione 2: struttura con prima proposta di isolamento alla base, con isolatori al di sotto di ogni pilastro;
3) Condizione 3: struttura con seconda proposta di isolamento alla base, con meno isolatori ma di diametro maggiore ed accoppiati a dispositivi di scorrimento tipo carrello;
Dopo un ampia analisi dei tre casi precedentemente esposti, vengono messi a confronto i risultati ottenuti nelle tre situazioni precedentemente riportate, in modo da meglio comprendere i miglioramenti ed i vantaggi ottenibili tramite l’introduzione di un sistema di isolamento alla base degli edifici, nonché confrontare i costi delle strutture nelle tre diverse condizioni di isolamento.
12
Monti, Diego. "Analisi del funzionamento dei dispositivi di isolamento sismico e applicazione progettuale ad un edificio in cemento armato." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8105/.
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La tesi ha l'obiettivo di studiare la tecnica di controllo passivo dell'isolamento sismico, comprenderne il funzionamento e applicarla ad un caso di studio (nello specifico un fabbricato ad uso civile abitazione costituito da 7 piani fuori terra) svolgendo le verifiche previste dal D.M. 14/01/08 e dalla Circolare 02/02/2009-
13
Adib, Natanzi Heshmatollah. "Effect of bonding variation and component combination on dynamic characteristics of compound semi-bonded carbon fiber reinforced elastomeric isolator (CSB-CFREI)." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59129.
Full textAbstract:
Over the past thirty years, seismic isolation has been considered a viable earthquake damage mitigation technique and has been implemented to protect new and existing structures. However, due to the high production cost and implementation challenges of conventional seismic isolators, application of this protective technology has been limited to high value buildings with important and sensitive contents. To ensure widespread application of the base isolation systems for ordinary residential and commercial buildings, especially in developing countries, not only the production cost must be reduced, but the implementation efficiency must improve as well. With this intention in this study, a new cost effective Elevated Semi-Bonded Carbon Fiber-Reinforced Elastomeric Isolator (ESB-CFREI) with lower production cost and higher implementation efficiency is designed, manufactured, and tested. The innovative ESB-CFREI undergoes lateral cyclic excitations with a unique deformation mechanism that differs from that of conventional Steel Reinforced Elastomeric Isolators SREI and Bonded and Un-Bonded Carbon Fiber Reinforced Elastomeric Isolators. The ESB-CFREI can be used in isolation as an independent “Component Isolator” or combined with other component isolators to form a CESB-CFREI “Compound Isolator.” According to the experimental results, isolators with different bonding levels (BL) are characterized by different overall dynamic characteristics. Depending on component combination configurations, the compound isolators have different average bonding values that result in different damping, effective lateral shear, and axial compression stiffness. Results from experimental tests on different compound isolators demonstrated that change in combination configuration effectively influences the dynamic characteristics of the compound isolator. Dynamic characteristics of component (ESB-CFREI) and compound isolator (CESB-CFREI) as low-cost seismic isolators were investigated by conducting analytical and experimental studies. The isolator’s effective lateral shear and axial compression stiffness along with the isolation efficiency (IE) were defined. The experimental outcome demonstrated the effect of bonding variation on the dynamic characteristics, performance, and efficiency of the ESB-CFREI. The effects of component combination on the dynamic characteristics of the compound isolators were also investigated. Component material testing to investigate the hyper-elastic behaviour of the isolator’s rubber component and long duration excitation tests to study the isolator’s durability and performance were conducted as well.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
14
Southern, Brian Mitchell. "Design and Characterization of Tunable Magneto-Rheological Fluid-Elastic Mounts." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/32654.
Full textAbstract:
This study of adaptable vibration isolating mounts sets out to capture the uniqueness of magnetorheological (MR) fluidâ s variable viscosity rate, and to physically alter the damping and stiffness when used inside an elastomeric mount. Apparent variable viscosity or rheology of the MR fluid has dependency on the application of a magnetic field. Therefore, this study also intends to look at the design of a compact magnetic field generator which magnetizes the MR fluid to activate different stiffness and damping levels within the isolator to create an adaptable and tunable feature.
To achieve this adaptable isolator mount, a mold will be fabricated to construct the mounts. A process will then be devised to manufacture the mounts and place MR fluid inside the mount for later compatibility with the magnetic field generator. This process will then produce an MR fluid-elastic mount. Additionally for comparative purposes, passive mounts will be manufactured with a soft rubber casing and an assortment of metal and non-metal inserts. Next, the design of the magnetic field generator will be modeled using FEA magnetic software and then constructed.
Stiffness or force/displacement measurements will then be analyzed from testing the isolator mount and magnetic field generator on a state-of-the-art vibration dynamometer. To vary the magnetic flux through the mount, an electro-magnet is used. To analyze the results, a frequency method of the stiffness will be used to show the isolators adaptation to various increments of magnetic flux over the sinusoidal input displacement frequencies. This frequency response of the stiffness will then be converted into a modeling technique to capture the essence of the dynamics from activating the MR fluid within the isolator mount.
With this methodology for studying the adaptability of an MR fluid-elastic mount, the stiffness increases are dependent on the level of magnetic field intensity provided from the supplied electro-magnet. When the electro-magnet current supply is increased from 0.0 to 2.0 Amps, the mount stiffness magnitude increase is 78% in one of the MR fluid-elastic mounts. Through comparison, this MR fluid-elastic mount at off-state with zero magnetic field is similar to a mount made of solid rubber with a hardness of 30 Shore A. With 2 Amps of current, however, the MR fluid-elastic mount has a higher stiffness magnitude than a rubber mount and resembles a rubber casing with a steel insert.
Moreover, when the current in the electro-magnet is increased from 0.0 to 2.0 Amps the equivalent damping coefficient in a MR fluid-elastic mount increases over 500% of the value at 0 Amps at low frequency. Through damping comparisons, the MR fluid-elastic mount with no current is similar to that of a mount made of solid rubber with a hardness of 30 Shore A. At full current in the electromagnet, however, the damping in the MR fluid-elastic mount is greater than any of the comparative mounts in this study.
Therefore, the results show that the MR fluid-elastic mount can provide a wide range of stiffness and damping variation for real-time embedded applications. Since many aerospace and automotive applications use passive isolators as engine mounts in secondary suspensions to reduce transmitted forces at cruise speed, the MR fluid-elastic mount could be substituted to reduce transmitted forces over a wider range of speeds. Additionally, this compact MR fluid-elastic mount system could be easily adapted to many packaging constraints in those applications.Master of Science
15
Gu, Xiaoyu. "Investigation of adaptive base isolation system utilising magnetorheological elastomer." Thesis, 2017. http://hdl.handle.net/10453/120190.
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University of Technology Sydney. Faculty of Engineering and Information Technology.Most of current researches on controllable or “smart” base isolation systems have been based on the hybrid of conventional base isolation system with active or semi-active dampers. Although supplementary dampers may help to reduce maximum displacement of base isolation systems and provide adjustable damping to suppress vibrations of the protected structure, it suffers some setbacks such as introduction of undesirable acceleration, limited performance due to the passive nature of base isolation, etc. Moreover, those “smart” supplementary dampers failed to add “smartness” or controllability toward working mechanism of isolation systems, i.e. decoupling ground motion from superstructures. In recent years, the development of adaptive base isolator utilising magnetorheological elastomer (MRE) shed light on “truly” smart base isolation systems in which isolators’ lateral stiffness can be controlled in real time by varying applied current. To this end, the MRE base isolation system exhibits a promising potential for ultimate seismic protection of civil infrastructures due to its ability to maximise, in real time, level of decoupling between ground motion and the superstructure. However, there have been only limited researches reported in this area. In addition, there is lack of throughout investigations, especially experimental investigation, on critical issues and feasibility related design and implementation of such MRE-based smart base isolated system, which is much needed for future development and application. This thesis is aimed at filling aforementioned research gap in development and application of MRE-based smart base isolated system by contributing new knowledge in the fields in terms of: i) modelling of the MRE isolator to capture its forward and inverse dynamic characteristics; ii) comprehensive investigation on the response time of MRE isolator and exploration of approaches to minimise the lag; iii) overcome obstacles in experimental realisation of smart base isolation system; iv) other innovations in seismic protection of civil infrastructures employing MRE isolator.