Projektiranje sustava regulacije vertikalne sile tribometra s uzorkom na disku uključujući aktivno i pasivno prigušenje vertikalnih vibracija

This paper presents the design of a computer-controlled pin-on-disk tribometer for friction characterization of various friction sliding pairs. The tribometer setup comprises two high-bandwidth servomotors for the control of the rotating disk and the normal load-related spindle drive, as well as a high-precision tri-axial piezoelectric force sensor for normal and tangential forces measurement. Since the spindle drive system is characterized by notable compliance effects, the normal force cascade control system is designed with the aim of vertical vibrations active damping. In order to compensate for the unevenness of the rotating disk surface and associated high-level perturbations in the specimen normal force, the normal force control system is extended with a feedforward compensator of the disk unevenness disturbance, and a dedicated leaf spring suspension system is designed. The effectiveness of the proposed system of vertical vibrations damping is verified experimentally.U članku je prikazan dizajn računalom upravljanog tribometra s uzorkom na disku za karakterizaciju različitih kliznih parova. Postav tribometra sadrži dva električna servomotora visokih dinamičkih performansi koji se koriste za regulaciju rotacijskog diska i navojnog vretena za generiranje normalne sile, te tro-osni piezoelektrični senzor za mjerenje normalne i tangencijalne sile. Kako je pogon navojnog vretena karakteriziran značajnom elastičnošću, kaskadni sustav regulacije sile je projektiran s ciljem aktivnog prigušenja vertikalnih vibracija. U svrhu kompenzacije značajnih neravnina površine rotacijskog diska i s njima povezanih velikih amplituda perturbacija normalne sile na uzorak, sustav regulacije normalne sile proširuje se unaprijednim kompenzatorom poremećaja uslijed neravnina površine diska, te za tu svrhu namijenjenim sustavom ovjesa s lisnatim oprugama. Učinkovitost predloženog sustava za prigušenje vertikalnih vibracija provjerena je eksperimentalnim putem

Brake-clutch squeal prediction and supression

This work studies the high frequency noise in brake–clutch systems known as squeal. The work is divided into two parts, the first is focused on the development of both a theoretical and experimental simplified model of a brake–clutch and the second is centred on squeal modelling in the real system. For the simple model, on the theoretical side, a FE model was developed including anisotropic material properties, pressure and speed dependent friction coefficient and friction damping. The pertinent characterisation tests were performed as needed. On the experimental side, squeal tests were performed in the test bench in order to check the ability of the system for squeal prediction. Once the model was thought as accurate enough, a methodology to decide over point structural modifications for squeal suppression based on the receptance function was designed. Using this process squeal was successfully eliminated from the simplified model both theoretically and experimentally. In the second part the modelling of squeal in a real brake–clutch system was tackled. With this objective a FE model of the whole system was developed and its validity was checked first by EMA and after, comparing the experimental squeal frequencies with the ones predicted by simulation. To finish, the methodology for structural modifications previously designed was applied to the system and several theoretical modifications were proposed and studied.Lan honetan balazta–enbrage unitate konbinatuetan agertzen den squeal izeneko frekuentzia altuko zarata aztertzen da. Lana bi zatitan banatuta dago: alde batetik, balazta–enbragearen eredu sinplifikatu bat garatu da, bai teorikoa zein esperimentala; bestetik, squeala sistema errealean modelizatu da. Eredu sinplean, alde teorikoari dagokionez, elementu finitutako eredu bat garatu da. Eredu honek marruskadura materialaren propietate anisotropoak, presio eta abiaduraren menpeko marruskadura koefizientea eta marruskadurak eragindako moteltzea kontutan hartzen ditu. Propietate hauek saiakuntza independentetan neurtu dira. Alde esperimentalean, squeal saiakuntzak burutu dira ereduak squeala aurreikusteko duen gaitasuna balioztatzeko asmoz. Behin eredua nahiko zehatza izanik, zarata kentzeko aldaketa estrukturalak proposatu eta baloratzeko metodologia bat diseinatu da. Proposatutako metodoa errezeptantzia funtzioan oinarrituta dago. Metodo honi esker squeala eredu teorikoan lehenengo eta ondoren saiakuntza bankuan kentzea posible izan da. Bigarren atalean, balazta–enbragearen modelizazioari ekin zaio squealari dagokionez. Helburu honekin, sistema osoaren eredu bat garatu da eta lehengo AME bidez eta gero squeal frekuentzia esperimentalak ereduak aurreikusitakoekin konparatuz balioztatu da. Azkenik, aldaketa estrukturalak proposatzeko metodologia sistema errealari aplikatu zaio eta aldaketa teoriko batzuk planteatu eta aztertu dira.El presente trabajo estudia el ruido de alta frecuencia que se da en los freno-embragues conocido como squeal. El trabajo se divide en dos partes, la primera enfocada en el desarrollo de un modelo simple tanto teórico como experimental del freno–embrague y la segunda centrada en la modelización del squeal en el sistema real. En lo referente al modelo simple, en la parte teórica se desarrolló un modelo de elementos finitos que incluía propiedades anisótropas para el material de fricción, un coeficiente de fricción dependiente de la presión y la velocidad y amortiguamiento por fricción. Estas propiedades se caraterizaron en los correspondientes ensayos independientes cuando fue necesario. En la parte experimental, se llevaron a cabo ensayos de squeal en banco con la idea de verificar la capacidad del modelo para predecir el squeal. Una vez que el modelo se consideró lo suficientemente exacto, se desarrolló una metodología para proponer y valorar modificaciones estructurales para la supresión de squeal. El método propuesto está basado en la función de receptancia. Gracias a este proceso fue posible eliminar el squeal del modelo primero en la teoría y a continuación en el banco de ensayos. En la segunda parte se aborda la modelización de squeal en un freno–embrague real. Con esto en mente se desarrolló un modelo de elementos finitos del sistema completo y se validó en primer lugar mediante AME y a continuación comparando las frecuencias experimentales de squeal con las predichas por la simulación. Por último, la metodología desarrollada para modificaciones estructurales se aplicó al sistema real y se propusieron y analizaron varias modificaciones teóricas

Interfacial Dissipative Phenomena in Tribomechanical Systems

The book is a collection of articles on the themes of contact mechanics and non-linear dynamics. In particular, the contribution focus on the mechanisms that lead to interfacial energy dissipation, which is a crucial quantity to determine in order to correctly predict the non-linear dynamic response of mechanical systems. The book is a collection of nine journal papers, among those one editorial, one review paper, and seven articles. The papers consider different dissipative mechanisms, such as Coulomb friction, interfacial adhesion, and viscoelasticity, and study how the system response and stability is influenced by the interfacial interactions. The review paper describes old and recent test rigs for friction and wear measurements, focusing on their performance and range of operability

Dry/wet sliding activation wear of pure Al / R. M. Nasir...[et al.]

An experimental work to study the wear behavior of pure Aluminium (Al) block was conducted against steel counter surface in Pin-on-Disc (POD) and the aluminium ball using four ball testing (4BT) method on dry/wet sliding wear technique at room temperature. Wear test conditions of 10-50 N load with sliding speed of 20-100 rpm was used to assess the friction coefficient, wear rate and the severance of wear mechanism on the damage surface. Due to the friction from the third body abrasive and protruded Al surfaces showcased mild wear with a steady state coefficient friction ranging from 0.0019-0.0043 for dry sliding and on wet condition ranging from 0.12-0.23 in vegetable oil (with average scar area of 8.0752 mm2) and from 0.058-0.085 for mineral oil used (with average scar area of 17.1549 mm2). Stress generation of the uncoated sample allowed the abraded plastic deformation to be classified as severe wear

44th Aerospace Mechanisms Symposium

The Aerospace Mechanisms Symposium (AMS) provides a unique forum for those active in the design, production and use of aerospace mechanisms. A major focus is the reporting of problems and solutions associated with the development and flight certification of new mechanisms

The 31st Aerospace Mechanisms Symposium

The proceedings of the 31st Aerospace Mechanisms Symposium are reported. Topics covered include: robotics, deployment mechanisms, bearings, actuators, scanners, boom and antenna release, and test equipment. A major focus is the reporting of problems and solutions associated with the development and flight certification of new mechanisms

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 13th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2022, held in Hamburg, Germany, in May 2022. The 36 regular papers included in this book were carefully reviewed and selected from 129 submissions. They were organized in topical sections as follows: haptic science; haptic technology; and haptic applications

Proceedings of the 40th Aerospace Mechanisms Symposium

The Aerospace Mechanisms Symposium (AMS) provides a unique forum for those active in the design, production and use of aerospace mechanisms. A major focus is the reporting of problems and solutions associated with the development and flight certification of new mechanisms. Organized by the Mechanisms Education Association, responsibility for hosting the AMS is shared by the National Aeronautics and Space Administration and Lockheed Martin Space Systems Company (LMSSC). Now in its 40th symposium, the AMS continues to be well attended, attracting participants from both the U.S. and abroad. The 40th AMS, hosted by the Kennedy Space Center (KSC) in Cocoa Beach, Florida, was held May 12, 13 and 14, 2010. During these three days, 38 papers were presented. Topics included gimbals and positioning mechanisms, CubeSats, actuators, Mars rovers, and Space Station mechanisms. Hardware displays during the supplier exhibit gave attendees an opportunity to meet with developers of current and future mechanism components. The use of trade names of manufacturers in this publication does not constitute an official endorsement of such products or manufacturers, either expressed or implied, by the National Aeronautics and Space Administratio

Advances in Lubricated Bearings

This reprint features 12 research articles that contribute to the research on lubricated bearings. The articles focus on the latest steps in understanding bearing operating behavior, its interaction with lubricants, and its role as a component in the drive train. In addition to the description of novel modeling approaches, a variety of experimental data are presented to provide interesting identification results as well as validation data for the research and engineering community

33rd Aerospace Mechanisms Symposium

The proceedings of the 33rd Aerospace Mechanisms Symposium are reported. JPL hosted the conference, which was held at the Pasadena Conference and Exhibition Center, Pasadena, California, on May 19-21, 1999. Lockheed Martin Missiles and Space cosponsored the symposium. Technology areas covered include bearings and tribology; pointing, solar array and deployment mechanisms; orbiter/space station; and other mechanisms for spacecraft