Microstructured n-th gradient continuum models including piezoelectric elements and electric circuits and some applications to acoustics

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Event details

Date and time 02.04.2015 09:3011:00  
Place and room
Speaker Prof. Francesco dell’Isola
Università di Roma - Sapienza
Bio: Professor Francesco dell’Isola holds the Chair of Mechanics of Structures at University of Rome "La Sapienza", Italy. He holds a degree in Physics and a Ph.D. in Mathematical Physics from Università Federico II of Naples, Italy. He is a mathematical physicist with a long experience in Continuum Mechanics, Mechanics of Solids and Structures and Vibration Control.

He holds  the United States Patent 6546316 (together with Vidoli and Henneke) and is co-author of 124 papers on peer reviewed international journals. He is scientific responsible of the Laboratorio Strutture e Materiali Intelligenti in Cisterna di Latina (Italy) and is Member of  the "Collegio dei Docenti" of the Doctoral School in Theoretical and Applied Mechanics Università di Roma La Sapienza and the Executive Committee of the Research Center M&MoCS, University of  L’Aquila (2012 – 2015). He was nominated as Membre du Conseil scientifique de l’Institut des sciences de l’ingénierie et des systèmes – CNRS (2014-2018). Finally he is Member of the Editorial Board of five International Journals and was also Member of the Scientific Committee of 13 International Conferences and Schools and was invited to hold more than 70 seminars or lectures in Europe and USA.
Category Conferences - Seminars
Abstract:
Composites may have a complex behaviour at macro-scale which is usually related to their micro-structure.  In particular composites may be endowed with a multiscale structure and may show at micro-level high contrast in physical and geometrical properties. As happens in living tissues, smart composites may be able to change their constitutive equations by means of self-controlling processes, which may be driven by mechanically suitably produced stimuli.

Some numerical, theoretical and experimental  results which were recently obtained will be presented showing that a class of fibrous fabrics must be modelled by means of second gradient continua (at least) and that one can conceive to design new and efficient metamaterials whose performances can be really exotic. In particular some microstructured fabrics constituted by fibres having bending stiffness (pantographic sheets) and nearly-inextensible are carefully studied using microscopic and macroscopic models. These examples show that: i) macro-models cannot belong to the class of Cauchy first gradient continua ii) some fabrics whose micro-structure is really simple may have a very complex macro-behaviour, iii) the dynamical response  of pantographic sheets can be really unexpected and iv) some delicate experimental set-ups are needed to measure their main physical properties.

A digression on the concept of generalised contact forces in higher gradient continua and on the boundary conditions naturally arising in the theory of generalised continua will be necessary  to consistently present the obtained result. This digression shows some of the the limits of standard continuum mechanics as conceived by Cauchy and motivates the conceptual effort (based on the Lagrangian Principle of Virtual Work) which has been started by Gabrio Piola, continued by Toupin, Mindlin and Germain and recently re-started by several research groups to found the correct conceptual frame for generalised continuum mechanics.

Some applications to wave propagation in complex materials are presented including some results about propagation in 2D pantographic structures which seem to indicate the existence of some solitary waves. In particular some micro-structures including piezoelectric actuators interconnected by optimal circuits are considered. The concept of optimal energy transduction is very fruitful in vibration and acoustic suppression.

Practical information

  • General public
  • Free

Organizer

  • Dr. Hervé Lissek, Head of the Acoustic Group, EE

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