40 research outputs found

    On the active deformations of hybrid specimens

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    Purpose – The purpose of this study concerns numerical studies and experimental validation of the mechanical behavior of hybrid specimens. These kinds of composite specimens are made up of thin carbon and glass substrates on which some Macro Fiber Composite ® (MFC) piezoelectric patches are glued. A proper design and manufacturing of the hybrid specimens as well as testing activities have been performed. The research activity has been carried out under the FutureWings project, funded by the European Commission within the 7th Framework. Design/methodology/approach – The paper describes the basic assumptions made to define specimen geometries and to carry out experimental tests. Finite element (FE) results and experimental data (laser technique measurements) have been compared: it shows very good agreement for the displacements’ distribution along the specimens. Findings – Within the objectives of the project, the study of passive and active deformation characteristics of the hybrid composite material has provided reference technical data and has allowed for the correct adaptation of the FE models. More in particular, using the hybrid specimens, both the bending deformations and the torsion deformations have been studied. Practical implications – The deformation capability of the hybrid specimens will be used in the development of prototypical three-dimensional structures, that, through the electrical control of the MFC patches, will be able to change the curvature of their cross section or will be able to change the angle of torsion along their longitudinal axis. Originality/value – The design of nonstandard specimens and the tests executed represent a novelty in the field of structures using piezoelectric actuators. The numerical and experimental data of the present research constitute a small step forward in the field of smart materials technology

    Study of Passive and Active Deformation Behaviors of Hybrid Specimens Made of Composite Substrates and MFC Piezoelectric Patches

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    An important step of the FutureWings project, funded by the European Commission within the 7th framework, concerns the numerical and experimental validation of the mechanical behavior of hybrid specimens. These kinds of specimens, that have been designed manufactured and tested within the project’s partnership, are made of thin carbon and glass substrates on which some MFC piezoelectric patches have been glued. Within the objectives of the project, the study of passive and active deformation characteristics of the hybrid composite material will help in the definition of the geometry of a small scale model of a self deforming wingbox. The paper describes the basic assumptions made to define the specimen geometries and to carry out the experimental tests. The comparison between the numerical (FE results) and the experimental data (laser technique measurements) has been executed: it shows a very good agreement for the displacements distribution along the specimens. More in particular both bending deformations and torsion deformations have been studied using the hybrid specimens: these type of deformation capability will be used in the development of a three-dimensional beam, with a cross section having an aerodynamic shape, that thank to the electric control of the MFC patches will be able to change the curvature of the profile's skeleton and to change the angle of attack of the profile by means of a torsional deformation

    A numerical comparison between a morphign wing and a traditional wing: aerodynamic effects of controlled piezoelectric deflections

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    One of the tasks of the FutureWings project, funded by the European Commission within the 7th framework, concerned the numerical validation of the mechanical behavior of a wing whose deflections can be controlled by means a suitable distribution of piezoelectric patches. Starting from a reference geometry two wing models have been implemented and analyzed adopting a Fluid Structure Interaction analysis technique: a traditional wing with an aileron surface and a morphing wing having a self-deforming leading edge and a self-deforming trailing edge thanks to the application of piezoelectric patches. In a first case a roll maneuver has been simulated. As piezoelectric patches the Macro Fiber Composite have been used. The aeroelastic analyses have been carried out at low mach number at the sea level and at high mach number at cruise level flight. From a practical point of view, as a preliminary, the work shows what are, at present, the technical possibilities of the technology related to the application of piezoelectric materials in the primary aerostructures field

    Energy harvesting and conversion - applications of piezoelectric transformer and transducer MEMS: Presentation held at IFAAP 2018 - Session 31am-A05-Energy Harvesters, ISAF-FMA-AMF-AMEC-PFM (IFAAP) Joint Conference in Hiroshima, May 27th - June 1st, 2018

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    A systematic investigation of the feasibility to integrate complete piezo-based power supply on silicon was done. Up to now, fully integrated off-line power supplies on chip are available as products for below 1 Watts. Higher power levels up to 10 Watts and more are strongly desired for many miniaturized applications as Off-Line LED light sources, integrated power supplies for communication devices as iPhone, portable devices for medical applications, portable beamers an others. The integration of high-efficient power supplies based on magnetic transformers (PT) including galvanic isolation is limited due to the physics of electromagnetism. Piezoelectric transformers can be integrated as MEMS when PZT material is applied on silicon to a height of several Micrometers to form an oscillating device which will be processed after micro-bonding in an etching process. Although power density of discrete PT is already high, it can be increased by a factor of 100 to 1000 in integrated devices on silicon taking advantage of uniform crystal structure of sputtering process and improved heat removal through silicon. Serial piezo-transformer-strings allow for high isolating voltage up to 4 kV and provide efficiency up to 95% or more, but unfortunately on the cost of significant large chip area. However, piezoelectric transformers will gain higher acceptance in power converters if a magnetic-field-free environment is requested as for magnetic resonance tomography. Promising piezoelectric applications can be found for transformer-transducer units to harvest ultrasonic energy, preferably in medical therapy-diagnosis applications, but further, in industrial autonomous sensor supplies with avoidance of electromagnetic disturbance. Piezoelectric energy harvesting becomes attractive using ultrasonic energy harvester MEMS with wide range frequency excitation using permanent magnet cantilever construction. Ultrasonic MEMS loudspeakers are miniaturized alternatives to traditional magnetic devices. The advantage of piezoelectric MEMS applications will result in an extreme miniaturization compared to conventional power conversion by magnetic or electrostatic solutions. High reliability including intelligent integrated functions in some cases may improve the practicability of piezoelectric MEMS

    Studies of the contribution of alternating electromagnetic fields toward material fatigue in 100Cr6

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    Purpose - The purpose of this paper is to show how controlled exposure of electromagnetic fields toward bearing steel vulnerates the microstructure. The ability of Barkhausen Noise signal processing is used for detecting phenomena Such as dislocation and subgrain formation processes as the beginning of later failures. Design/methodology/approach - A Barkhausen noise signal measurement equipnient is used for detecting subsurface distress of 100Cr6 as a function of the applied electromagnetic and mechanical stress. Barkhausen noise signal is mathematically processed by use of fractal dimension analysis. Findings - The paper cleary reveals significant impact of electromagnetic field in junction with mechanical loading. Electromagnetic impact depends on the magnitude of the field. Research limitations/implications - Research limitations are given by the fact that in real field applications, e.g. wind power plants, bearings are exposed by multiple influences and the methodology is not applicable to those conditions. Practical implications - The methodology can be applied to real field applications in condition monitoring systems. Up to now, no reasonable on-line measurement is in use determining sub surface fatigue phenomena. The paper hence, reveals the possibility to raise condition monitoring into a new perspective. Originality/value - The use of Barkhausen noise signal processing, as presented here, is original with respect to real field applications, such as wind power plants with a high demand in condition monitoring, especially off-shore plants

    Biotite: new tools for a versatile Python bioinformatics library

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    BACKGROUND Biotite is a program library for sequence and structural bioinformatics written for the Python programming language. It implements widely used computational methods into a consistent and accessible package. This allows for easy combination of various data analysis, modeling and simulation methods. RESULTS This article presents major functionalities introduced into Biotite since its original publication. The fields of application are shown using concrete examples. We show that the computational performance of Biotite for bioinformatics tasks is comparable to individual, special purpose software systems specifically developed for the respective single task. CONCLUSIONS The results show that Biotite can be used as program library to either answer specific bioinformatics questions and simultaneously allow the user to write entire, self-contained software applications with sufficient performance for general application

    Acute Lung Functional and Airway Remodeling Effects of an Inhaled Highly Selective Phosphodiesterase 4 Inhibitor in Ventilated Preterm Lambs Exposed to Chorioamnionitis

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    Phosphodiesterase (PDE) inhibition has been identified in animal studies as a new treatment option for neonatal lung injury, and as potentially beneficial for early lung development and function. However, our group could show that the inhaled PDE4 inhibitor GSK256066 could have dose-dependent detrimental effects and promote lung inflammation in the premature lung. In this study, the effects of a high and a low dose of GSK256066 on lung function, structure and alveolar development were investigated. In a triple hit lamb model of Ureaplasma-induced chorioamnionitis, prematurity, and mechanical ventilation, 21 animals were treated as unventilated (NOVENT) or 24 h ventilated controls (Control), or with combined 24 h ventilation and low dose (iPDE1) or high dose (iPDE10) treatment with inhaled GSK 256066. We found that high doses of an inhaled PDE4 inhibitor impaired oxygenation during mechanical ventilation. In this group, the budding of secondary septae appeared to be decreased in the preterm lung, suggesting altered alveologenesis. Ventilation-induced structural and functional changes were only modestly ameliorated by a low dose of PDE4 inhibitor. In conclusion, our findings indicate the narrow therapeutic window of PDE4 inhibitors in the developing lung
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