40 research outputs found

    Proceedings of SIRM 2023 - The 15th European Conference on Rotordynamics

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    It was our great honor and pleasure to host the SIRM Conference after 2003 and 2011 for the third time in Darmstadt. Rotordynamics covers a huge variety of different applications and challenges which are all in the scope of this conference. The conference was opened with a keynote lecture given by Rainer Nordmann, one of the three founders of SIRM “Schwingungen in rotierenden Maschinen”. In total 53 papers passed our strict review process and were presented. This impressively shows that rotordynamics is relevant as ever. These contributions cover a very wide spectrum of session topics: fluid bearings and seals; air foil bearings; magnetic bearings; rotor blade interaction; rotor fluid interactions; unbalance and balancing; vibrations in turbomachines; vibration control; instability; electrical machines; monitoring, identification and diagnosis; advanced numerical tools and nonlinearities as well as general rotordynamics. The international character of the conference has been significantly enhanced by the Scientific Board since the 14th SIRM resulting on one hand in an expanded Scientific Committee which meanwhile consists of 31 members from 13 different European countries and on the other hand in the new name “European Conference on Rotordynamics”. This new international profile has also been emphasized by participants of the 15th SIRM coming from 17 different countries out of three continents. We experienced a vital discussion and dialogue between industry and academia at the conference where roughly one third of the papers were presented by industry and two thirds by academia being an excellent basis to follow a bidirectional transfer what we call xchange at Technical University of Darmstadt. At this point we also want to give our special thanks to the eleven industry sponsors for their great support of the conference. On behalf of the Darmstadt Local Committee I welcome you to read the papers of the 15th SIRM giving you further insight into the topics and presentations

    AIMETA 2005. Atti del XVII Congresso dell'Associazione italiana di meccanica teorica e applicata. Firenze, 11-15 settembre 2005

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    The volume collects the contributions presented at the XVII national congress of AIMETA. The contributions are grouped according to the various sectors of theoretical and applied mechanics and are offered by a vast scientific community. In addition to the classical sectors, themes of interdisciplinary significance and of considerable interest and highly innovative content were added, for the analysis of which small exchange symposia were proposed. Organised according to 52 sessions (plenary and parallel), the volume contains 290 scientific works that are mainly the result of international cooperation. Therefore, the work represents a significant picture of the current situation and future prospects for mechanics

    On semi-active inerters for improving machining productivity

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    The inerter is a mechanical element, synthesised in 2002 as an analogue to the electrical capacitor. Originally used in Formula 1 racing as the `J-damper', its potential has since been explored in other vehicles, as well as for vibration control of civil structures. In very recent years, some study has been given to the design and control of semi-active inerters. Such devices would be capable of varying their inertance in response to a control signal. To date, no study has been made of the semi-active inerter in the context of machining chatter. This undesirable form of vibration, leading to poor surface finish on machined parts, is a major issue in machining. The growing requirements of high speed machining of lightweight, flexible parts mean that the need to develop new strategies to tackle chatter will only increase. This thesis seeks to fill this gap in the literature. As a feasibility study, two chatter suppression strategies are developed using a simplified single degree of freedom chatter model. Both strategies assume the existence of an ideal semi-active inerter placed between the vibrating element and ground, allowing the natural frequency to be adjusted on-line. The first of these strategies, discrete inertance variation, is analogous to an existing lobe seeking strategy conducted by changing the spindle speed. It is shown that, with relatively modest ranges of inertance, this is an achievable strategy for high speed machining. The second strategy relies on cyclically adjusting the natural frequency to disrupt self-excited vibration. It is found that the amplitude of this variation is the important characteristic, rather than the ratio of the frequency of inertance variation to the tooth passing frequency. In both cases, the need to be able to rapidly control inertance is noted. The design needs of a semi-active helical inerter are considered, with magnetorheological fluid providing the semi-active control. Three different layouts are studied using quasi-static models. The bypass valve type layout is selected as the most promising for future study. The design of the valve is considered and a new optimisation scheme is developed which better suits the need of the bypass valve than previous schemes. The inerter model is extended into a quasi-dynamic model, which allows the varying inertance to be considered. This model would be key for developing any practical control scheme. Prototype inerters were designed and tested. Initially an oil-based designed is built, followed by a design using magnetorheological fluid. The prototype was tested using a servo-hydraulic actuator, with the goal of validating the models developed in the previous chapter. Unfortunately, trapped air in both systems led to these results being inconclusive in both cases. The use of magnetorheological fluid for flow directional control in this way is unusual at this scale and this work is important for any future researchers who wish to work with the fluid in this way. With this in mind, the issues encountered with the experimental rig are further analysed. Improvements to the design and filling method are proposed. Some more substantial design changes are also presented. Finally, some focus is given to the practical issues of implementing semi-active inerters in machining. The need to miniaturise the design to fit into modern machine tools is highlighted. Two areas in which this would be less of an issue -- fixturing and robotic machining -- are discussed. Notably, key challenges for robotic machining include the number and placement of the inerters, and whether new strategies would be needed to tackle mode-coupling chatter

    SMARTI - Sustainable Multi-functional Automated Resilient Transport Infrastructure

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    The world’s transport network has developed over thousands of years; emerging from the need of allowing more comfortable trips to roman soldiers to the modern smooth roads enabling modern vehicles to travel at high speed and to allow heavy airplanes to take off and land safely. However, in the last two decades the world is changing very fast in terms of population growth, mobility and business trades creating greater traffic volumes and demand for minimal disruption to users, but also challenges, such as climate change and more extreme weather events. At the same time, technology development to allow a more sustainable transport sector continue apace. It is within this environment and in close consultation with key stakeholders, that this consortium developed the vision to achieve the paradigm shift to Sustainable Multifunctional Automated and Resilient Transport Infrastructures. SMARTI ETN is a training-through-research programme that empowered Europe by forming a new generation of multi-disciplinary professionals able to conceive the future of transport infrastructures and this Special Issue is a collection of some of the scientific work carried out within this context. Enjoy the read

    Scientific Advances in STEM: From Professor to Students

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    This book collects the publications of the special Topic Scientific advances in STEM: from Professor to students. The aim is to contribute to the advancement of the Science and Engineering fields and their impact on the industrial sector, which requires a multidisciplinary approach. University generates and transmits knowledge to serve society. Social demands continuously evolve, mainly because of cultural, scientific, and technological development. Researchers must contextualize the subjects they investigate to their application to the local industry and community organizations, frequently using a multidisciplinary point of view, to enhance the progress in a wide variety of fields (aeronautics, automotive, biomedical, electrical and renewable energy, communications, environmental, electronic components, etc.). Most investigations in the fields of science and engineering require the work of multidisciplinary teams, representing a stockpile of research projects in different stages (final year projects, master’s or doctoral studies). In this context, this Topic offers a framework for integrating interdisciplinary research, drawing together experimental and theoretical contributions in a wide variety of fields

    WINDERFUL Wind and INfrastructures

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    WINDERFUL (an acronym for Wind and INfrastructures: Dominating Eolian Risk For Utilities and Lifelines) is the title of a research project carried out by eight Italian Universities from the end of 2001 to the end of 2003. The project was centred on how "to keep a city running and ensuring quality services during and after major windstorms", avoiding "major failures" of engineering facilities and main infrastructures. The book reports the main results obtained in the project, and for each typology the tool for assessing its reliability are discussed, together with the criteria for its improvement

    Characterization and Modelling of Composites, Volume II

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    Composites have been increasingly used in various structural components in the aerospace, marine, automotive, and wind energy sectors. Composites’ material characterization is a vital part of the product development and production process. Physical, mechanical, and chemical characterization helps developers to further their understanding of products and materials, thus ensuring quality control. Achieving an in-depth understanding and consequent improvement of the general performance of these materials, however, still requires complex material modeling and simulation tools, which are often multiscale and encompass multiphysics. This Special Issue is aimed at soliciting promising, recent developments in composite modeling, simulation, and characterization, in both design and manufacturing areas, including experimental as well as industrial-scale case studies. All submitted manuscripts will undergo a rigorous review and will only be considered for publication if they meet journal standards

    Preview-based techniques for vehicle suspension control: a state-of-the-art review

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    Abstract Automotive suspension systems are key to ride comfort and handling performance enhancement. In the last decades semi-active and active suspension configurations have been the focus of intensive automotive engineering research, and have been implemented by the industry. The recent advances in road profile measurement and estimation systems make road-preview-based suspension control a viable solution for production vehicles. Despite the availability of a significant body of papers on the topic, the literature lacks a comprehensive and up-to-date survey on the variety of proposed techniques for suspension control with road preview, and the comparison of their effectiveness. To cover the gap, this literature review deals with the research conducted over the past decades on the topic of semi-active and active suspension controllers with road preview. The main formulations are reported for each control category, and the respective features are critically analysed, together with the most relevant performance indicators. The paper also discusses the effect of the road preview time on the resulting system performance, and identifies control development trends
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