1,121 research outputs found

    A Magnetorheological Damper with Embedded Piezoelectric Force Sensor: Experiment and Modeling

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    This chapter describes configuration, fabrication, calibration and performance tests of the devised self-sensing MR damper firstly. Then, a black-box identification approach for modeling the forward and inverse dynamics of the self-sensing MR damper is presented, which is developed with the synthesis of NARX model and neural network within a Bayesian inference framework to have the ability of enhancing generalization.Department of Civil and Environmental Engineerin

    MR Fluid Damper and Its Application to Force Sensorless Damping Control System

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    Vibration suppression is considered as a keyresearch field in civil engineering to ensure the safety and comfort of their occupants and users of mechanical structures. To reduce the system vibration, an effective vibration control with isolation is necessary. Vibration control techniques have classically been categorized into two areas, passive and active controls. For a long time, efforts were made to make the suspension system work optimally by optimizing its parameters, but due to the intrinsic limitations of a passive suspension system, improvements were effective only in a certain frequency range. Compared with passive suspensions, active suspensions can improve the performance of the suspension system over a wide range of frequencies. Semi-active suspensions were proposed in the early 1970s [1], and can be nearly as effective as active suspensions. When the control system fails, the semi-active suspension can still work under passive conditions. Compared with active and passive suspension systems, the semi-active suspension system combines the advantages of both active and passive suspensions because it provides better performance when compared with passive suspensions and is economical, safe and does not require either higher-power actuators or a large power supply as active suspensions do [2]

    A magnetorheological damper with embedded piezoelectric force sensor : experiment and modeling

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    2010-2011 > Academic research: refereed > Chapter in an edited book (author)Version of RecordPublishe

    A Novel Experimental Approach Using A Reconfigurable Test Setup For Complex Nonlinear Dynamic Systems

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    Experimental nonlinear dynamics is an important area of study in the modern engineering field, with engineering applications in structural dynamics, structural control, and structural health monitoring. As a result, the discipline has experienced a great influx of research efforts to develop a versatile and reliable experimental methodology. A technical challenge in many experimental studies is the procurement of a device that exhibits the desired nonlinear behavior. As a result, many researchers have longed for a versatile, but accurate, testing methodology that has complete freedom to simulate a wide range of nonlinearities and stochastic behaviors. The objective of this study is to develop a reconfigurable test setup as a tool to be used in a wide range of nonlinear dynamic studies. The main components include a moving mass whose restoring force can accurately be controlled and reprogrammed (with software) based upon measured displacement and velocity readings at each time step. The device offers control over nonlinear characteristics and the equation of dynamic motion. The advantage of having such an experimental setup is the ability to simulate various types of nonlinearities with the same test setup. As a result, the data collected can be used to help validate nonlinear modeling, system identification, and stochastic analysis studies. A physical test apparatus was developed, and various mechanical, electrical, and programming calibrations were performed for reliable experimental studies. To display potential uses for the reconfigurable approach, examples are presented where the device has been used to create physical data for use in change detection and deterioration studies. In addition, a demonstration is presented of the device’s ability to physically simulate a large-scale orifice viscous damper, commonly used in vibration mitigation in bridges and buildings. For a large-scale viscous damper, physical testing is required to ensure structural design properties. However, due to the large scale of the dampers, expensive dynamic loading tests can be carried out at a very iii limited number of facilities. Using the reconfigurable test setup, the dynamic signature of the large-scale viscous damper can accurately be simulated with pre-collected data. The development of a system capable of emulating the restoring force of a nonlinear device with software is a novel approach and requires further calibration for increased reliability and accuracy. A discussion regarding the challenges faced when developing the methodology is presented and possible solutions are recommended. The methodology introduced by this apparatus is very promising. The device is a valuable experimental tool for researchers and designers, allowing for physical data collection, modeling, analysis, and validation of a wide class of nonlinear phenomena that commonly occur in a wide variety of engineering applications

    Damping Behaviour of Slender Telecommunications Structures

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    During the last two decades, the development of mobile telecommunications (‘telecoms’) technologies has resulted in an increased number of antennas to be accommodated around us on different kinds of structures. From new, short monopoles to old high guyed masts, all are considered sensitive flexible structures under wind, many of which are required to hold more equipment than their initial design loading capacity. The dynamic analysis of these structures has been neglected for years, in part as it is clearly a field that requires further investigations with new modern methodologies and knowledge. Within the industry, damping is the topic that provides the most uncertainty between existing expert consultants. The complex nature of damping arises from the high deviation between similar structures and the number of involved sources that modify this behaviour, from boundary conditions to aerodynamic effect, or nonlinear amplitude and frequency dependence relationship. In this PhD research, several projects related to response-data acquisition were used to determine how damping behaves for each selected typology structure (monopoles, lattice towers and high guyed masts). Old and new estimation techniques have been applied after human and wind-ambient excitation to provide reliable data to verify current approaches of assessing damping and provide new clues and perspective about understanding damping in this kind of structures. The research counts on a study of the generic structural damping component on short structures compounded by soil-foundation component and material-connection defined by free decaying responses. A study of non-linearities exist on the response that help to determine sources of damping, and finally, diverse studies of monitoring systems under wind excitation were carried out to allow the research to study actual service response to extract aerodynamic damping, and the accuracy of current drag factors for different wind effects. This new perspective provides essential knowledge to structural engineers when designing current and future structures, advising on the effectiveness and feasibility of external damping providers, not just as an option to minimise aeroelastic vortex shedding effects, but also to reduce the buffeting response with the consequential structural capacity improvement. Results also show the deficiency of current standards and recommendations in the estimation of dynamic properties, especially on damping matter

    Modelling of Hysteresis in Vibration Control Systems by means of the Bouc-Wen Model

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    The review presents developments concerning the modelling of vibration control systems with hysteresis. In particular, the review focuses on applications of the Bouc-Wen model that describes accurate hysteretic behaviour in vibration control devices. The review consists of theoretical aspects of the Bouc-Wen model, identification procedures, and applications in vibration control

    Enhancing the collaboration of earthquake engineering research infrastructures

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    Towards stronger international collaboration of earthquake engineering research infrastructures International collaboration and mobility of researchers is a means for maximising the efficiency of use of research infrastructures. The European infrastructures are committed to widen joint research and access to their facilities. This is relevant to European framework for research and innovation, the single market and the competitiveness of the construction industry.JRC.G.4-European laboratory for structural assessmen

    Co-Simulation in Virtual Verification of Vehicles with Mechatronic Systems

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    In virtual verification of vehicle and mechatronic systems, a mixture of subsystems are integrated numerically in an offline simulation or integrated physically in a hardware-in-loop (HIL) simulation. This heterogeneous engineering approach is crucial for system-level development and widely spreads with\ua0the industrial standard, e.g. Functional Mock-Up Interface (FMI) standard.For the engineers, not only the local subsystem and solver should be known,\ua0but also the global coupled dynamic system and its coupling effect need to be\ua0understood. Both the local and global factors influence the stability, accuracy, numerical efficiency and further on the real-time simulation capability.In this thesis, the explicit parallel co-simulation, which is the most common and closest to the integration with a physical system, is investigated.In the vehicle development, the vehicle and the mechatronic system, e.g. an\ua0Electrcial Power Assisted Steering (EPAS) system can be simulated moreefficiently by a tailored solver and communicative step. The accuracy and\ua0numerical stability problem, which highly depends on the interface dynamics, can be investigated similarly in the linear robust control framework. The\ua0vehicle-mechatronic system should be coupled to give a smaller loop gain for robustness and stability. Physically, it indicates that the splitting part\ua0should be less stiff and the force or torque variable should be applied towardsthe part with a higher impedance in the force-displacement coupling. Furthermore, to compensate the troublesome low-passed and delay effect fromthe coupling, a new coupling method based on H∞ synthesis is developed,\ua0which can improve the accuracy of co-simulation. The method shows robustness to the system dynamics, which makes it more applicable for a complex\ua0vehicle-mechatronic system
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