HARPOCRATES has begun December, 1st 2015 and ended November, 30th 2017.
The work performed in this period can be divided as follows:
1. Training activities of the beneficiary Dr. Marco Miniaci. The training has included: (i) theoretical tutoring on phononic crystals, metamaterials, piezoelectricity and (ii) extensive laboratory training. The first part of the training has been carried out by Prof. B. Morvan and MdC R. Sainidou while the second one mainly by Prof. B. Morvan.
Specifically, the first part of the training concerned the acquisition of the basics of wave propagation phenomena in periodic structures made of identical building blocks (named unit cells) capable of spectral and spatial control of waves due to two fundamental properties: frequency-dependent directionality and band gap (BG) effect.
The second part of the training has concerned the acquisition of preparatory competencies in view of the experimental phase. This included ad-hoc training on: (i) a vast range of piezoelectric (contact or air-coupled) transducers to excite and detect elastic waves in complex configurations; (ii) Scanning Laser Doppler Vibrometer (SLDV) for contactless measurements; (iii) anechoic chamber for the "intrinsic" acoustic material characterization and the assessment of the transmitted and reflected sound properties; (iv) a tube of impedance for sonic range characterization of scaled specimen and single building block (unit cell); (v) power amplifier and generator, dedicated frame for motorized displacements, portable anechoic chamber, etc.
In parallel, Dr. Marco Miniaci has been supervised by Prof. B. Morvan in developing complementary soft skills for the independent management of the project.
2. The investigation of BG nucleation with respect to the material properties and geometrical arrangement and the implementation of numerical models in order to investigate the device dispersive behaviour.
In this phase Dr. Marco Miniaci, assisted by Prof. Morvan, explored different geometries capable to exhibit special dynamic behaviour. In parallel, he learned how to implement periodic boundary conditions within the FE software Comsol Multiphysics. Assisted by MdC A. Madeo, a semi-analytical model based on relaxed micromorphic continuum model with weighted free and gradient micro-inertia has been implemented and used to describe the dynamical behaviour of a real two-dimensional phononic crystal for a wide range of wavelengths.
3. Investigation of the abilities of filtering / control of waves of the proposed device. This phase of the project has been accomplished following both numerical and experimental approaches, subsequently. In particular, the implementation of numerical models aimed at predicting the multi-physics behaviour of the phononic device at the frequencies of interest has been carried out.
4. The "Synthesis and Dissemination" of the main results resulting from actions 1-3 has been brought together in order to provide a consistent synthesis level in which theories, methods and experimental validations have been presented at a national and international levels.
Results have been published in high quality international peer-reviewed journals such as (Physical Review Letters, Applied Physics Letters, New Journal of Physics, etc.) and presented at national and international meetings, as well as at regular seminars.
Also, during the first phase, the kick-off meeting with Aircelle industry which supports the project has also been organized and held at the LOMC on February, 24th 2016. From that discussion important issues related to industrial current technological breakthrough needs emerged and a plan for the next regular meetings (1 each 8 months) has been discussed.
Dissemination activities included the participation to national and international conferences, research-periods in foreign laboratories (Georgia Institute of technology, California Institute of Technology) and the organization of an international workshop (10th - 11th October at the University of Trento)
HARPOCRATES overall objectives have also been discussed during the GdR CNRS META (Le groupement de recherche METamatériaux Acoustiques pour l'ingénierie - the research group dealing with acoustic metamaterials for engineering -
http://events.femto-st.fr/GdR-META/bienvenue-sur-site-internet-du-gdr-meta.(s’ouvre dans une nouvelle fenêtre)) kick-off meeting held at the "Institut de Physique du Globe" of Paris (January, 22nd 2016), during the which potential researchers dealing with a very similar research subject have been identified.
