1,720,976 research outputs found
Power transmission systems: from traditional to magnetic gearboxes
Get PDFL'abstract è presente nell'allegato / the abstract is in the attachmen
Multicriteria design of an electromagnetic hammer
No full textIn this paper, a Pareto based multicriteria design procedure for a linear motor driving an electromagnetic demolition hammer is presented. The hammer application requires high dynamical performance as it must deliver at the same time high value of impact energy and frequency of cycle. The uncertain characteristic of the medium on which the hammer head will impact has to be taken into account in an integrated electromechanical model of the system that could guide the control strategy of the supply system. Requirements of the application are stated and some preliminary analysis that lead to the choice of a Linear Permanent Magnet Synchronous Motor are described. The integrated electromechanical model, taking into account the modelling of the head impact on the soil is described. Some of the principal results show that the solution is not unique but comes out of a spread of possibilities so that Pareto criterion is used to sort them out. Simulation results obtained on the main operative hammer quantities are presented and discussed
Energy harvesting from bearings rotation in a seeding agriculture machine
No full textEnergy harvesting is one of the emerging sustainable and innovative solutions for supplying energy to remote sensors for the IoT world. This process is going on also in the agricultural sector where the need to monitor machines devoted to farming and other agricultural activities is growing. In particular, it addresses the energy needs of agriculture while minimizing its ecological impact. In this work, the energy harvesting technology is exploited to remotely monitor the performances of seeding disk bearings. Specifically, an harvester that collects the rotating kinetic energy of seeding disks is designed to detect if they are properly working. When the seeding disks are rotating, electric power is generated and a signal is sent ensuring everything is in order. However, in the event of a malfunction, no electrical power is produced, leading to the activation of a warning on the main board which notifies about the malfunctioning of a seeding disk. The design of the harvester is based on an axial flux generator topology and it is developed by performing evaluations on the reaction torque to counteract the magnetic attractive force and on the electromotive force which can be harvested in order to send the signal. By developing and implementing this energy harvesting technology for remote monitoring, this work aims to improve the efficiency and reliability of agricultural machines, ultimately contributing to increased productivity and reduced downtime in farming operations
LUPOS: Open-Source Scientific Computing in Structural Dynamics
No full textLUPOS is a parametric FEM code developed in MATLAB aiming to merge different simulative characteristics: to provide a complete open-source 3D FEM code suitable for analysing elements formulations, assembly approaches, reduction techniques in a complete parametric scheme; to allow parametric analyses and integrating results, giving all matrices details and formulations; to integrate this parametric FEM code in Multi-Body and nonlinear integration processes in time domain such as Simulink.
The acronym of LUPOS in Italian-English Lupo’s, or better in Latin lupus, lupi, is associable to the wolf, symbol of smart and aggressive animal. What better name could be chosen?
The reason to develop another software for dynamics relies in the main idea to share concepts about mechanical modelling and simulation tools that can be applied from academic examples to industrial applications in an intuitive and easy way, but maintaining all the mathematical rigour and numerical explanations, in particular taking into account parameters that can extend to families of structures.
Some examples of different levels of complexities are analysed for static, real and complex modal analyses and finally in rotordynamics in both time and frequency domains
Experimental and numerical mode shape tracing from components to whole motorbike chassis
No full textThis paper aims to analyse the most influent component mode shapes on the dynamic properties of a whole motorbike frame. Experimental and numerical modal analyses have been carried out on chassis, swingarm, engine, wheel and different subsystems of increasing complexity. The component global modes shapes are traced from component to assembly with both Modal Assurance Criterion. The most influent mode shapes of each component are highlighted and their effects on the global motorbike dynamics are
discussed. The component to assembly method results to be a preliminary tool to have an objective evaluation of the most important modes of components on which possible improvements can be suggested
ELECTRO-MECHANICAL DESIGN OF A MAGNETIC GEAR PROTOTYPE
Get PDFA magneto-mechanical approach is proposed to design a magnetic gear prototype. Firstly, an integrated tool for electromechanical simulations is developed, starting from a topological parametric model of a planetary magnetic gear (PMG). Then a CAD model is realised with a progressive rise in complexity, in order to achieve quickly exchangeable configurations for different experimental tests. Three different solutions are designed with advantages and drawbacks. Finally, a block-oriented dynamic model of a PMG, inserted in a mechanical driveline, is developed in Matlab/Simulink environment using the results of magneto mechanical simulations, to virtually test the dynamic behaviour of the device
Assembling Uncertainty Effects on the Dynamic Response of Nominally Identical Motorbike Components
No full textThe chassis and swingarm are the main components of the motorbike frame. The dynamic response of these components strongly influences the frame flexibility and consequently the motorbike dynamics. However, there may be variability in nominally identical manufactured components. The uncertainty may arise from many sources including geometric tolerances, material properties, and variability in the manufacturing and assembling process, for example, adhesive bonding of hollow parts. The presence of uncertainties can significantly alter motorbike component dynamic response and modal properties, and thus their overall performance during a racing competition. Therefore, competitive riders test several components during the racing weekend to find the specific motorbike frame with which they are more comfortable.
In this chapter, experimental modal analyses have been carried out on the flexible components of a motorbike frame. The experimental campaign results have demonstrated significative differences in frequency response functions, natural frequencies and damping of motorbike components. Modal assurance criterion and other indexes have been used to compare mode shapes of the seemingly identical components and to assess possible crossing and veering phenomena, due to uncertainty
High-speed tracked vehicle model order reduction for static and dynamic simulations
Get PDFIn this paper, a model order reduction strategy is adopted for the static and dynamic behaviour simulation of a high-speed tracked vehicle. The total number of degree of freedom of the structure is condensed through a selection of interface degrees of freedom and significant global mode shapes, for an approximated description of vehicle dynamic behaviour. The methodology is implemented in a customised open-source software to reduce the computational efforts. The modelled tracked vehicle includes the sprung mass, the unsprung masses, connected by means of torsional bars, and all the track assemblies, composing the track chain. The proposed research activity presents a comprehensive investigation of the influence of the track chain, combined with longitudinal vehicle speed, on statics and vehicle dynamics, focusing on vertical dynamics. The vehicle response has been investigated both in frequency and time domain. In this last case road-wheel displacements are assumed as inputs for the model, under different working conditions, hence considering several road profiles with different amplitudes and characteristic excitation frequencies. Simulation results have proven a high fidelity in model order reduction approach and a significant contribution of the track chain in the global dynamic behaviour of the tracked vehicle
Self-adaptive neural network model predictive anti-jerk control of electric powertrains
No full textThe study introduces a proof-of-concept self-adaptive neural network model predictive control (SA-NNMPC) system, which uses a neural network as main component of the prediction model, for the anti-jerk control of electric vehicles. Through the adaptation mechanism of the network and cost function weights during vehicle operation, which is activated when the plant behaves significantly differently from its digital twin, the SA-NNMPC architecture adjusts to the progressive vehicle aging, or to the replacement of hardware parts, which is expected to be an important feature of next-generation vehicles. Validation tests and simulations show that the neural network accurately replicates the drivetrain dynamics of the considered electric vehicle, and, for nominal conditions, already leads to a performance improvement of the NNMPC implementation – which can run in real-time on a rapid control prototyping unit – with respect to a benchmarking nonlinear model predictive anti-jerk controller. Moreover, the preliminary simulation results confirm the potential of the proposed architecture in terms of: i) adaptability to operating conditions not covered in the original training, and variations of vehicle parameters; and ii) auto-tuning of the algorithm when applied to different vehicles
Parametric Experimental Modal Analysis of a Modern Violin Based on a Guarneri del Gesù Model
No full textMechanical effects and dynamic behaviour of a modern violin, built on a Guarneri del Gesù model, were examined via parametric experimental modal analysis. Among the few mobile components of a violin, the soundpost has a particular relevance for the final acoustic performance, even if its dimensions are extremely small. Therefore, the aim of this first research is to understand the violin sensitivity to the soundpost position considering its influence on the overall structural-vibrational behaviour. Experimental modal analysis was performed in six different configurations, related to different positions of the soundpost inside the violin, including both the outer possible locations and optimal position, generally defined by the violinist according only to the perceived best acoustic performance. Six “Signature” modes were identified and tracked in all configurations, comparing mode shapes, damping and natural frequencies of involved modes, in order to find a correlation between mechanical vibrations and acoustic performance of the instrument. The effects of the soundpost position on the modal properties of the “Signature” mode shapes are highlighted and discussed. Finally, the potential role of soundpost as a practical engineering tool to improve the signature and sound quality is discussed
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