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Reference : UMR8520-MARMIN-001
Workplace : LILLE
Date of publication : Thursday, March 12, 2020
Scientific Responsible name : Marco Miniaci
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 June 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Elastic waves are omnipresent in our lives, from the simple propagation of sound in the air (which allows us to communicate) to micro-electromechanical systems (MEMS) for the detection of physical phenomena or large-scale catastrophic events such as earthquakes and tsunamis.
Although a full control of wave propagation is not yet possible, recent developments in Condensed Matter of Physics have allowed the emergence of a new class of composite materials (generally called metamaterials) capable of exhibiting extraordinary dynamic characteristics, such as negative refraction, collimation, wave focusing, extraordinary transmission, acoustic masking, etc.
Metamaterials are (quasi) periodic composites made up of building blocks, also said unit cells, which allow spatial and spectral control of waves often due to band gap effects. Band gaps are frequency ranges in which no wave propagation is allowed.
The basic idea of this thesis is the hypothesis that the working principle of metamaterials is already exploited in nature, where it gave rise to optimized designs oriented towards specific objectives, due to the evolutionary development process, such as for example in the case of the Stomatopod dactyl club, which turned out to be a formidable biological hammer resistant to damage, or in the case of the wing Bunaea alcinoe, presenting an extraordinary vibro-dynamics capable of creating an acoustic camouflage against the echolocation of bats.
The main objective of the thesis is therefore to design, manufacture and experimentally characterize innovative metamaterials inspired by biological systems in order to create a light and compact device (operating in a sub-wavelength regime) valid for the control of wave propagation in noise reduction applications. Due to the scalability of the wave equations, other areas of application at different scales can be investigated.
The thesis will begin with a bibliographic analysis on the state of the art of the subject. Next, particular attention will be devoted to the development of design tools, exploring and potentially integrating analytical and numerical approaches, with the aim of achieving specific computing means capable of predicting the dynamic behaviour of bio-inspired metamaterials. The final phase of the thesis will include the fabrication of the samples and its experimental characterization. As the final stage, a comparison between the experimental and numerical results is expected, possibly leading to a demonstrator.
The project is funded by the EU in the framework of a H2020 FET Open project on elastic metamaterials entitled "BOHEME: Bio-inspired Hierarchical Metamaterials".
The project partners are the University of Trento (Italy), CNRS (France), Imperial College London (United Kingdom), EMPA and ETH Zurich (CH) and IMP-PAN ( Poland). As a consequence, beyond the periodic monitoring at the ISEN provided by the project supervisors, scientific exchanges with the other partners of the project may be foreseen.
The project will require periods of work in office (bibliography revision, coding, etc.) as well as experimental measurements in the laboratory.
Constraints and risks
The project does not involve any particular constraint or risk since it is mainly based on numerical analyses and wave propagation experiments. Being aware of the normal security protocols for attending a laboratory of acoustics (the candidate will be trained for it) and the precautions necessary for workers at the video terminal will be sufficient to guarantee the proper execution of the thesis.
Young engineer or holder of a Master in physics, engineering or similar disciplines.
Fluency in English (strict requirement because the project provides for international exchanges with non-French speaking partners), general knowledge in acoustics and mechanics, familiarity with coding (for example MATLAB) and finite elements. Strong motivation towards the experimental aspects of the project.
Applicants interested in the offer are invited to submit their CV and cover letter through the site https://emploi.cnrs.fr/ .
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