Headmaster of MSSMat laboratory (Laboratoire Mécanique des Sols, Structures et Matériaux, Ecole Centrale Paris). Head of « structure-structure interaction » research team. Professor Ben Dhia main research concerns the modeling of interaction between structural components. Precisely, among Professor Ben Dhia developments are: the friction contact numerical modeling through three dimensional mixted formulation, extension of friction contact modeling to vibrating structures under impacts, extension of the Arlequin strategy and its analysis for multiscale mechanical problems.
Coupling of models and scales in the Arlequin framework
J. Buffe (Thales Alenia Space, France)
Head of the mechanical department of THALES Alenia Space, Satellites and telecommunication Branch (CANNES). General Coordinator of mechanical activities accross THALES Alenia Space. Senior Member of the 3AF (Aeronautics Astronautics French Association) into the "Stuctures" Commission. Active member in the development and implementation of European standardizations in the space sector (ECSS) and especially for the mechanical aspects.
New considerations on the validation and on the optimization of designs in the space domain
Abstract If there is one domain where optimizations on the designs are mandatory with regard to the mass constraints, where the reliability on the performances has to be well handled and where dynamic and static environments are of first importance, there are, for sure, the space activities and more specially the satellites.The aim of this proposed presentation for Medyna 2013 conference is to talk about the different ways of dealing with the question of this complex situation and the compromise which has to be found. The current way is commonly called a deterministic process by using standard rules whatever the designs and by minimizing the safety margins. Another way is to use a probabilistic approach allowing the decider to design at an optimized technico economic level with regard to the performances and their criticality. Finally, another way could be to use a robustness approach when a lack of knowledge on the characteristics is there.This new consideration on the validation of the designs is more and more up to date since the variability on the characteristics of the components and on the elementary pieces is increasing. The industrial world, even in space field, is faced to some evolutions dealing with eventual different characteristics to those already seen in the past and, so, impacting the current rules for validation and, by consequence, the optimizations.Otherwise, due to the so very few numbers of specimens involved in the satellites production and with a so scattered growing distribution of the performances, the philosophy for an adequate qualification by test is also impacted with an appropriate choice on models and/or with a validation by an analytical process to be done in parallel.As a conclusion, the presentation will be focused on the sensitization of this new situation which could be relatively critical for satellites and on the interest of some new methods to put into place in order to handle as much as possible the designs and to get the most appropriate solution for the optimization and robustness purposes.In that context, a pertinent view has to be provided on the designs and their robustness. The risk analysis on the final objective to be reached for the satellite performance has to be done by using the growing complexity of the situations to be met. More than previously, the decision for the research of the best design through a probabilistic approach or a robustness approach in its choice has to be taken for the most efficient final product with the technico economic goals.
Peter Eberhard (Professor University of Stuttgart, Germany)
Peter Eberhard is Full Professor of Mechanics and Director of the Institute of Engineering and Computational Mechanics at the University of Stuttgart in Germany. He studied Mechanical Engineering with focus on Dynamics and Control and did his doctoral degree on optimization of mechanical systems and his habilitation about contact problems. After a professorship at the University Erlangen-Nuremberg he joined the University of Stuttgart. He and his coworkers research interests include Multibody Systems, Contact Mechanics (especially particles), Optimization, Mechatronics and Control, Biomechanics, and Uncertainties. He received the Richard-von-Mises-Award and he holds a Honorary Professorship from the Nanjing University of Science and Technology in China. He is author and coauthor of several books and about 275 scientific papers.
Modern Model Reduction in Dynamics - much more than just a Mathematical Toy
Abstract
In this talk some introduction to the model reduction of elastic structures is given so that these huge models can be used in a dynamic multibody simulation. During the last decade there was a lot of research activity going on and the focus shifted from modal methods to approaches using moment-matching or balanced truncation. These methods are not just mathematically beautiful but are also very useful for engineering applications. Examples will be shown including also comparisons with different methods. A special focus will be on the model reduction of coupled elastic structures.
Daniel Juvé (Professor Ecole Centrale de Lyon)
Professor at Ecole Centrale de Lyon, head of the Centre Acoustique and head of the excellency laboratory on Acoustics (CeLyA) . Research interests concern: generation of sound by turbulent flows; subsonic and supersonic jets; grazing flows over cavities; wall-pressure fluctuations and Propagation of acoustic waves in non homogeneous and random moving media; micrometeorological effects in atmospheric sound propagation. Prof D. Juvé was awarded Chavasse Prize of the French Acoustical Society (1990) Great Prize Alexandre Joannidès of the French Academy of Sciences (2001, together with Christophe Bailly), fellow of the Acoustical Society of America (1998), associate fellow in the American Institute of Aeronautics and Astronautics (AIAA, 2009), member of the French Acoustical Society (SFA), of the French Association for Aeronautics and Space (AAAF), of the French Society of Mechanics (AFM). He is editor of the Journal of Sound and Vibration (Acoustics) and the International Journal of Aeroacoustics. He is member of the Aeroacoustics Specialists Committee of the Council of European Aerospace Societies (CEAS- ASC), Evaluation and Orientation Committee of Department DSNA of Onera, Management Committee of the French Network on Aeroacoustics IROQUA and Scientific Committee of the French Research Foundation for Aeronautics and Space (FRAE).
Turbulent wall-pressure fluctuations: models and relation with fluid dynamics computations
Abstract
Modeling wall-pressure fluctuations beneath a turbulent boundary layer is an important issue for the prediction of flow-induced structural vibrations and subsequent noise emission.
In this talk we will first give a short review of current models of point-spectra, spatial correlations and cross-spectra of turbulent pressure fluctuations. The possibility of using fluid dynamics computations (averaged “RANS” computations or time-resolved “LES”) to identify the various flow parameters used in these models will be discussed. Finally recent results obtained in measuring or computing the “acoustic” component (associated with supersonic wavenumbers) of wall-pressure fluctuations will be presented together with a new experimental set-up designed to study the effect of favorable or adverse mean-pressure gradients.
Anders Nilsson (Royal Institute of Technology, Stockholm)
Anders Nilsson holds MSc in Engineering Physics from University of Lund, Sweden and Dr.Tech. in Sound and Vibration from Chalmers University. Anders Nilsson has worked on problems relating to the propagation of sonic booms at Boeing Co., Seattle , USA. At Det Norske Veritas he became head of the Acoustics Department at the Research Division. At Veritas Anders Nilsson worked on the propagation of structure borne sound in large built up structures like ships and on the excitation of plates from flow and cavitation. Anders Nilsson was head of the Danish Acoustical Institute for four years. His main activity in Denmark was building acoustics. In 1987 Anders Nilsson was appointed professor of Applied Acoustics at KTH in Stockholm, Sweden. He was also the head of the Department of Vehicle Engineering and the founder and head, until 2002, of the Marcus Wallenberg Laboratory of Sound and Vibration Research (MWL). Anders Nilsson has been a guest professor at James Cook University, Australia, INSA-Lyon, France and the Institute of Acoustics, Chinese Academy of Sciences in Beijing. He is the author of the book Vibro-Acoustics, the first volume published in 2012 and the second in early 2013. Anders Nilsson is since 2008 professor emeritus at MWL, KTH. His main interests are problems relating to composite structures as well as vehicle acoustics.
Goran Pavic (Professor INSA Lyon)
Goran Pavić holds BSc in Mechanical Engineering and PhD in Acoustics and Vibration. After having spent 24 years in research in shipbuilding, electrotechnical and mechanical industries, he was elected to professorship at the National Institute of Applied Sciences in Lyon, France. His duties involve research and teaching in vibration, acoustics and signal processing.
The present research activities of G. Pavić are in the areas of vibroacoustics of mechanical systems, virtual noise synthesis and energy related techniques of sound and vibration analysis. G. Pavić has participated in 9 international projects concerning noise and vibration, out of which in 4 as the coordinator, in several tens of industry funded projects as well as in the European Doctorate in Sound and Vibration programme. He is former associate editor of Acta Acustica and current associate editor of Technical Acoustics; former director of International Institute of Acoustics and Vibration and member of 2 ISO standardisation committees. He has published a number of journal articles and has presented a number of papers on various topics in the field of sound and vibration.
Virtual Noise Synthesis
Abstract
The synthesis of noise of an industrial product can be done by sub-structuring it into its basic components. A particular sub-structuring method predicts the trends in the overall noise by combining data from the real source(s) with a simplified modelling of the main frame. The coupling between the source(s) and the frame is ensured by impedance coupling rules. The critical components are the noise sources which have to be characterised by measurements. The characterisation techniques are not simple, but reveal a lot of useful information to the designer apart from providing the input data to synthesis method itself. The simplified frame model has the advantage of being robust and easy to implement. The output of the synthesis is the noise level and the noise waveform for audible reproduction. The paper outlines the basics of the source characterisation techniques and of the noise synthesis approach accompanied by several examples.
Pedro Ribeiro (Faculty of Engineering, University of Porto, PR)
Pedro Ribeiro earned a Doctor of Philosophy degree at the Institute of Sound and Vibration Research (ISVR), University of Southampton, in 1998. He currently is an Assistant Professor at the Department of Mechanical Engineering, Faculty of Engineering of the University of Porto, where he lectures subjects in the area of Applied Mechanics.
His research field is nonlinear dynamics of structures, mainly with geometrical nonlinearity, but with some incursions into plasticity. He has been and is involved in research projects related with nonlinear dynamics of structures. Currently he supervises two PhD theses in non-linear oscillations of composite laminates.
Pedro Ribeiro is author or co-author of over forty international journal papers. He present several communications in conferences and other international meetings, presented seminars in diverse universities and lectured in CISM advanced school “Exploiting Nonlinear Behaviour in Structural Dynamics” in 2010. He was chairman of EUROMECH Colloquium 483, “Geometrically non-linear vibrations of structures” in 2007, has been involved in the organization of a few symposia and acted as co-editor of journal special issues related with nonlinear dynamics.
Non-linear modes of vibration of structural elements
Abstract
When structures experience large amplitude vibrations, some characteristics present in modes of vibration of linear systems are not preserved. It is intended in this presentation to explore the extension of the mode of vibration notion to vibrations in the geometrically non-linear regime. After a short review on work and concepts presented by different authors, the presentation proceeds to the analysis of periodic, conservative, free vibrations of structural elements, specifically beams, plates and shells. For that purpose, the displacement components are expanded as sums of products of functions of time and functions of space. Writing the time functions as truncated Fourier series, sets of algebraic equations in the frequency domain are derived and, by solving these equations, one can investigate the variation of frequency and shape of vibration with the vibration amplitude. With the procedures presented, it is also possible to analyse internal resonances, that is, couplings between modes that are induced by the non-linearity and that lead to interesting oscillations.
Massimo Ruzzene (Professor Georgia Institue of Technology, Atlanta)
Massimo Ruzzene is a Professor in the Schools of Aerospace and Mechanical Engineering at Georgia Institute of Technology. He received a Ph.D in Mechanical Engineering from the Politecnico di Torino (Italy) in 1999. He is author of approximately 105 journal papers and about 130 conference papers, and has participated as a PI or co-PI in various research projects funded by the Air Force Office of Scientific Research (AFOSR), the Army Research Office (ARO), the Office of Naval Research (ONR), NASA, the US Army, TRW Corporation, DARPA and the National Science Foundation (NSF). Most of his current and past research work has dealt with structural health monitoring, wave propagation analysis, high frequency vibration modeling, and vibration and noise control techniques. M. Ruzzene is a Fellow of ASME, and member of AIAA, AHS, and ASA.
Nonlinearities and multifield interactions for adaptive metamaterials
Abstract
Metamaterials consist of engineered microstructural assemblies that exhibit superior properties in comparison to less-composed or naturally-occurring materials. Their unusual wave properties include band-gap behavior, response directionality, left-handedness, and negative acoustic refraction, among others. These features, and their application for the design of acoustic filters, waveguides, logic ports, and ultrasonic transducer arrays, motivate the investigation of elastic wave propagation in micro-structured media.
The seminar presents in particular the directional properties of periodic media, as defined by their ability to direct waves in preferential direction. Such properties are first illustrated on simple spring-mass systems, and subsequently demonstrated in complex structural lattices operating in linear and nonlinear deformation regimes. In addition, periodic arrays of electromechanical resonators, and lattices that undergo topological changes resulting from structural instabilities are discussed as examples of adaptive metamaterials. Tunable local resonating systems, and local instabilities are investigated as effective means to provide the considered periodic assemblies with adaptive bandgaps and wave steering characteristics.
Jing Tian (President of Acoustical Society of China)
Professor TIAN Jing, president of Chinese Society of Acoustics; Honorary fellow of International Institute of Acoustics and Vibration (IIAV); Executive Editor in Chief for Acta Acustica, Director member of Technical Committee of National Acoustical Standardization.
Graduated from the Department of Physics of Nanjing University majored in acoustics on February 1982, then he got his Master’s degree in 1984 and his Ph.D. from Institute of Acoustics, Chinese Academy of Sciences (IACAS) on December 1991. As a researcher on electro-acoustic and noise control for more than 30 years, Prof. Tian has been the principal investigator for 40 research projects supported by various funding bodies including National Ministry of S&T, National Natural Science Foundation, Chinese Academy of Sciences (CAS), and other organizations. The research covers several areas of acoustics: active noise and vibration control, electronic anti-noise communication devices, audio characteristic signal control, acoustical MEMS, transmission and evaluation of traffic noise and applications of finite amplitude sound wave.
Industrial State of Art
Bernard Troclet (Senior Expert in Structural Mechanics, professor at ENS Cachan)
Bernard TROCLET is R&D project manager (Structural Engineering) in EADS ASTRIUM ST and professor at ENS CACHAN. He is engineer from ISAE-ENSMA (Ecole Nationale Supérieure de Mécanique et d’Aéronautique de Poitiers) and obtained is Habilitation of Research in Mechanics & Energetics from Paris VI. His domains of expertise are Dynamics computation, Acoustic, deterministic and random Vibration, Mid & High Frequency Analysis and Pyrotechnic shocks.
Synthesis of Ariane 4 & Ariane 5 vibroacoustic studies and perspectives
Abstract
The objective of this conference is to present the vibroacoustic approach on Ariane launchers. Early in the design development of the Ariane 5 launcher, it was anticipated that the acoustic environment would be a severe case load. Consequently, very soon, noise reduction means have been investigated.
This conference will address :
- The acoustic environment experienced by the launchers lift-off and during flight ascent and the work undertaken to reduce noise surrounding the ARIANE 5 launch vehicle and the noise inside the Fairing on the one hand. The reduced scale test to characterize the lift-off noise and to investigate potential noise reduction means, the Fairing full scale acoustic test are presented,
- And the methods used to estimate the vibroacoustic response of launch vehicles on the other hand.
Finally, perspectives, particularly in the field of mid frequency response will be presented.
Eberhard Haug is one of the founding members of ESI Group, the well-known virtual prototyping company, where he held the position of Scientific Director. He is now retired and acts as a consultant. Eberhard Haug graduated from the University Stuttgart (W.G.) in Civil Engineering and he earned his Ph.D. degree in Structural Engineering at the University of California, Berkeley, where he wrote a program for the large displacement finite element analysis of lightweight cable and membrane structures. He was a Research Associate at the University of Stuttgart with Professors Frei Otto and J.H. Argyris. At ESI Group, he was the driving force behind the development of various non-linear FE analyses programs and material model developments and he is the principal inceptor of the world's premier crash, occupant safety and stamping simulation codes. His recent computational developments focused on biomechanics. He has published many papers on the theory and industrial application of modern numerical simulation techniques. His recent consulting activities include the wind simulation of lightweight structures.
Numerical Design and Analysis of Flexible Structures
This article extends the application of ESI Group Products into the spectacular field of Special and Lightweight structures, a domain situated in the field of high-rise building construction, in recent SL Rasch GmbH and ESI France joint projects.
ESI Group is a global compagny working on Virtual prototyping and Testing and is a pioneer in Realistic FE Simulation, in particular for pre-certification of structural integrity with respect of accidental and extreme operating conditions. SL-Rasch GmbH, an internationally operating architectural and engineering office, located in Stuttgart, Germany, is specialized in the architectural and structural design of Special and Lightweight structures, often made of pre-stressed flexible cables and membrane fabrics. The industrial application of this principle was pioneered in the 1950-s by the German architect Professor Frei Otto. Flexible buildings made with fiber reinforced technical membranes are particularly sensitive to wind loads. ESI France has developed, calibrated and validated an analysis and design methodology to investigate wind load effects, ranging from constant wind velocity profiles to input of wind fields with natural turbulence (gusts) (Ph.D. thesis A. Michalski). While for most conventional high-rise buildings the structural response to wind load can be evaluated via computational fluid
