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Meyer Y.,Higher Institute of Mechanical Engineering, Paris | Collet M.,FEMTO ST Institute
Mechanical Systems and Signal Processing

The sensitive electronic components used in military and aerospace applications endure some intense vibrations. These vibrations have some disturbing effects on the stability and on the service life of these devices. So, protecting these elements becomes a major economic and strategic stake. Vibration isolation can be applied to different levels of the on-board systems. Indeed, it is advisable to isolate electronic components either at the rack level or at the board level or at the component level. In this paper, the last solution is chosen because of low moving masses which imply low control energies. An active suspension system is located between the host board and the sensitive element to be isolated. This designed control system uses a simple Integral Force Feedback strategy. This vibration isolation control is stable for its collocated version and does not need a numerical model of the system to be controlled. Robustness of the system is asymptotically guaranteed. The proposed isolation device, made of alumina for passive structure and made of PZT and PVDF for transducing layers, is experimentally tested. Experimental performances are compared with theoretical performances. © 2010 Elsevier Ltd. All rights reserved. Source

Pinho M.,CNRS Acoustic Lab of Du Maine University | Brouard B.,CNRS Acoustic Lab of Du Maine University | Genevaux J.M.,CNRS Acoustic Lab of Du Maine University | Dauchez N.,Higher Institute of Mechanical Engineering, Paris | And 3 more authors.
Journal of Magnetism and Magnetic Materials

The use of ferrofluid seals in mechanical systems can lead to viscous damping that affects their dynamic behavior. This paper describes an investigation into local viscous properties in the case of an axial harmonic force. The influence of magnetic field level, shear stress amplitude and frequency are studied. Even for ferrofluid particles in a highly saturated magnetic field, it is shown that viscosity increases with magnetic intensity, decreases with the frequency of harmonic excitation and is not sensitive to shear rate amplitude. Viscosity is lower for oscillatory flows than for steady flows. © 2009 Elsevier B.V. All rights reserved. Source

Benjeddou A.,Higher Institute of Mechanical Engineering, Paris
European Journal of Computational Mechanics

An experimentally proved smart concept for piezoceramic direct torsion actuation is here numerically assessed with regards to the bonding and segmentation influence on its behavior and performance. The TRESCA and deflection criteria analysis indicates that the actuator sandwiching with composites contributes to its integrity enhancement, but in the cost of its performance reduction. It is also found that modeling the core inter-rows and composites inter-layers bonding is more influential than that of the core rows segmentation. The conducted open-circuit modal analysis confirms that the inter-rows adhesive softens the actuator, while the inter-layers one stiffens it. Besides, the conducted adhesive parametric analysis indicates that, as expected, the most influential bonding parameters are its thickness and shear modulus. © 2011 Lavoisier, Paris. Source

Pinho M.,CNRS Acoustic Lab of Du Maine University | Genevaux J.M.,CNRS Acoustic Lab of Du Maine University | Dauchez N.,Higher Institute of Mechanical Engineering, Paris | Brouard B.,CNRS Acoustic Lab of Du Maine University | And 2 more authors.
Journal of Magnetism and Magnetic Materials

Damping induced by ferrofluid seals in ironless loudspeakers is investigated in this paper. The magnetic field is steady but not spatially constant. A model to determine the viscous damping coefficient induced by the ferrofluid seal is derived. It is a function of geometrical parameters and local viscosity of the ferrofluid in which dependence from magnetic field, shear rate and frequency is accounted for. Comparison with experimental results shows a good agreement for the thinner seals. An overestimation of the damping is observed for higher volumes. This discrepancy comes from geometric irregularities of the magnet assembly made out of several tiles. © 2014 Elsevier B.V. Source

Yvars P.-A.,Higher Institute of Mechanical Engineering, Paris
ICED 11 - 18th International Conference on Engineering Design - Impacting Society Through Engineering Design

In this paper we are studying a deterministic constraint based approach to solve Pareto bi-criterion optimization problems in design. After presenting the use of multi-objective optimization methods in design, the CSP method and the several ways to solve it is introduced. A quick overview of CSP application in product engineering is given too. Moreover, we introduce an optimization point of view for CSP and we propose a deterministic alternative to stochastic methods for solving Pareto biobjective system sizing problems. An example in mechanical system optimization is given via the case study of the Pareto bi-criterion optimal design of a bolt coupling. The case is modeled as a Constraint Satisfaction Problem on both discrete and real variables. Finally, the numerical results and the Pareto frontier are exposed. Source

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