LTDS

Saint-Étienne, France
Saint-Étienne, France
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Tateo F.,FEMTO ST Institute | Collet M.,FEMTO ST Institute | Ouisse M.,FEMTO ST Institute | Ichchou M.N.,LTDS
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

A recent technological revolution in the fields of integrated MEMS has finally rendered possible the mechanical integration of active smart materials, electronics and power supply systems for the next generation of smart composite structures. Using a bi-dimensional array of electromechanical transducers, composed by piezo-patches connected to a synthetic negative capacitance, it is possible to modify the dynamics of the underlying structure. In this study, we present an application of the Floquet-Bloch theorem for vibroacoustic power flow optimization, by means of distributed shunted piezoelectric material. In the context of periodically distributed damped 2D mechanical systems, this numerical approach allows one to compute the multi-modal waves dispersion curves into the entire first Brillouin zone. This approach also permits optimization of the piezoelectric shunting electrical impedance, which controls energy diffusion into the proposed semi-active distributed set of cells. Furthermore, we present experimental evidence that proves the effectiveness of the proposed control method. The experiment requires a rectangular metallic plate equipped with seventy-five piezo-patches, controlled independently by electronic circuits. More specifically, the out-of-plane displacements and the averaged kinetic energy of the controlled plate are compared in two different cases (open-circuit and controlled circuit). The resulting data clearly show how this proposed technique is able to damp and selectively reflect the incident waves. © 2013 SPIE.


Canales D.,École Centrale Nantes | Leygue A.,École Centrale Nantes | Chinesta F.,École Centrale Nantes | Cueto E.,University of Zaragoza | And 4 more authors.
Key Engineering Materials | Year: 2015

A new efficient updated-Lagrangian strategy for numerical simulations of material forming processes is presented in this work. The basic ingredients are the in-plane-out-of-plane PGD-based decomposition and the use of a robust numerical integration technique (the Stabilized Conforming Nodal Integration). This strategy is of general purpose, although it is especially well suited for plate-shape geometries. This paper is devoted to show the feasibility of the technique through some simple numerical examples. © (2015) Trans Tech Publications, Switzerland.


Canales D.,École Centrale Nantes | Cueto E.,University of Zaragoza | Feulvarch E.,LTDS | Chinesta F.,École Centrale Nantes
Key Engineering Materials | Year: 2014

Friction Stir Welding (FSW) is a welding technique more and more demanded in industry by its multiple advantages. Despite its wide use, its physical foundations and the effect of the process parameters have not been fully elucidated. Numerical simulations are a powerful tool to achieve a greater understanding in the physics of the problem. Although several approaches can be found in the literature for simulating FSW, all of them present different limitations that restrict their applicability in industrial applications. This paper presents a new solution strategy that combines a robust approximation method, based on natural neighborhood interpolation, with a solution separated representation making use of the Proper Generalized Decomposition (PGD), for creating a new 3D updated-Lagrangian strategy for addressing the 3D model while keeping a 2D computational complexity. © 2014 Trans Tech Publications, Switzerland.


Youssef S.,University of Monastir | Ben Salem W.,University of Monastir | Brosse A.,LTDS | Hamdi H.,LTDS
International Journal of Machining and Machinability of Materials | Year: 2011

During grinding, commonly used as a finishing process, the integrity of part can be altered in many ways. Actually, the generation of high temperature level into the workpiece generally causes burning marks, structural and metallurgical transformation, and consequently influence the built up of residual stress. Therefore, a control of this process is of great importance to ensure both precise dimensions and small tolerance, required to have good working parts. The relationship between the metallurgic transformation and residual stress field generated by grinding of hardened AISI 52100 steel is discussed in this work. The obtained results indicate that the increasing of the grinding speed for low depth of cut induces a rise in the value of residual stress. This tendency is reversed for higher depths of cuts. Moreover, it is largely approved that there is a relationship between the states of the residual stress, metallurgical transformations and the kinetics of cooling induced by the grinding process. Copyright © 2011 Inderscience Enterprises Ltd.


Onder O.,Joseph Fourier University | Paris H.,Joseph Fourier University | Rech J.,LTDS
Mechanics and Industry | Year: 2012

In industrial area, drilling is one of the most commonly used machining operations. Today, conventional drilling methods have found their limits in deep hole drilling. To be able to push these limits, we have developed a new technology: vibratory drilling. The aim of this study is to determine the influence of the twist drill geometry on performance of the self vibratory drilling head. For that reason, it is necessary to identify the geometrical properties which have the strongest influence on axial vibrations of twist drill and on chip fragmentation. Moreover, we have also validated the experimental results by a simulator which can predict the behaviour of the self vibratory drilling head by taking into account geometrical defects of the tool. © AFM, EDP Sciences 2012.


Valiorgue F.,LTDS | Brosse A.,ESI France | Robin V.,AREVA | Gilles P.,AREVA | And 2 more authors.
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2013

The chaining of manufacturing processes is a major issue for industrials who want to understand and control the quality of their products in order to ensure their in-service integrity (surface integrity, residual stresses, microstructure, metallurgical changes, distortions,⋯). Historically, welding and machining are among the most studied processes and dedicated approaches of simulation have been developed to provide reliable and relevant results in a industrial context with safety requirements. As the simulation of these two processes seems to be at an operational level, the virtual chaining of both must now be applied with a lifetime prediction prospect. This paper will first present a robust method to simulate multipass welding processes that has been validated through an international round robin. Then the dedicated "hybrid method", specifically set up to simulate finish turning, will be subsequently applied to the welding simulation so as to reproduce the final state of the pipe manufacturing and its interaction with previous operations. Final residual stress fields will be presented and compared to intermediary results obtained after welding. The influence of each step on the final results will be highlighted regarding surface integrity and finally ongoing validation works and numerical modeling enhancements will be discussed. Copyright © 2013 by ASME.


Jolivet S.,Arts et Metiers ParisTech | Mezghani S.,Arts et Metiers ParisTech | Isselin J.,Arts et Metiers ParisTech | Giraudeau A.,Arts et Metiers ParisTech | And 2 more authors.
Key Engineering Materials | Year: 2015

For automotive gear manufacturers, reducing gear noise while maintaining the gear load-carrying capacity as well as the wear resistance has become more and more important. Macro- and micro-geometrical defects have long been studied in order to explain the vibratory behavior of gears. However, the contribution of the micro-scale roughness of the flanks, essential in the gear contact mechanics, has not yet been fully understood. This paper addresses this issue where gears were manufactured with two industrial finishing processes (grinding and power-honing) while having the same macro-scale characteristics. Tridimensional topographical features of teeth surface were hence measured using a three-dimensional white light interferometer. As manufactured surface topographies are highly complex, irregular, and multiscale, all the teeth surfaces were characterized in the entire wavelength band using a multiscale method based on wavelets transform. Vibration performances of the gears were then tested on a single-stage low powertrain. Results demonstrate the influence of micro-roughness scales on vibrations amplitude. © (2015) Trans Tech Publications, Switzerland.


Valiorgue F.,LTDS | Brosse A.,ESI France | Naisson P.,LTDS | Rech J.,LTDS | And 2 more authors.
Applied Thermal Engineering | Year: 2013

This paper will present the infrared thermography principles applied to the thermal fields recording during orthogonal cutting of 316L stainless steel. This paper is divided in three parts. First, emissivity curve of 316L is extracted by warming up a sample and dividing recorded grey levels by black body ones. This first step requires the design of special equipment that allows controlling temperatures and atmosphere while recording. Next, the IR camera equipped with a microscope is integrated in a CNC lath to record grey levels while orthogonal cuttings of 316L samples. To finish, the recorded grey levels fields are then numerically post treated using homemade emissivity curve to plot the thermal gradient created during machining. All these works are important to increase the cutting analytical and numerical models accuracy especially in the thermal field prediction. © 2013 Elsevier Ltd. All rights reserved.


Rezig S.,LTDS | Toscano R.,LTDS | Rusaouen G.,INSA Lyon | Lozano V.,LTDS
Energy Procedia | Year: 2015

A critically important quantity of energy is required nowadays to heat and ventilate our buildings. In order to reduce this energy demand, we need to characterize the convective indoor air movements in large scale spaces like building rooms. 3D Lagrangian Particle Tracking is used here; hence a feedback schema has been designed, it applies multi-view information to correct uncertainties in particle positioning. Moreover, a multi-scale based approach has been developed and tested with experimental and synthetic datasets. The method shows good robustness and efficiency against different kinds of noise and allows a generally applicable algorithm thanks to the use of automatic scale selection. On the other hand, the particle tracking is another challenging problem. Therefore, a new tracking algorithm based on fuzzy Kalman filtering is proposed. The Kalman filter is used to optimally estimate the new position of the particles based on their actual position. A quantitative comparison of the performances of this technique and other commonly used tracking algorithms allows validating the method. © 2015 The Authors.


Rezig S.,LTDS | Toscano R.,LTDS | Rusaouen G.,INSA Lyon | Lozano V.,LTDS
Journal of Applied Fluid Mechanics | Year: 2016

3-D Lagrangian Particle Tracking (3DLPT) is becoming widely used to characterize the convective indoor air movements in large scale spaces. The need to implement a robust algorithm led us to develop a multi-scale based approach to detect features (Helium filled soap bubbles). On the other hand, the particle tracking is another challenging problem. To this end, a new tracking algorithm based on fuzzy Kalman filtering is proposed in this paper. The Kalman filter is used to optimally estimate the new position of the particles based on their actual position. In our approach, the initial particle positions are represented with multivariate fuzzy sets.

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