Abstract:

The ability to control, manipulate and structure sound and vibration with precision has long been a central goal in acoustics and mechanical engineering. Recent advances in the design of metastructures, engineered architectures with tailored wavelength or subwavelength features, have opened new frontiers in this pursuit. These structures enable unprecedented control over wave propagation, reflection, absorption, transmission and localization, far beyond the limits of conventional materials. By structuring matter at different scales, metastructures offer a versatile platform for reimagining how we interact with acoustic and vibrational energy, with implications spanning from noise mitigation to vibration isolation, sensing and energy harvesting.

In this general seminar, I will present an overview of recent research developments in the field of acoustic and elastic metastructures, with a focus on how these architected materials can be used to structure and control sound and vibrations. By leveraging the physics of special resonances, wave interference and hybridization, and symmetry-breaking, metastructures enable functionalities such as wave steering, focusing, isolation, and absorption, all within compact, lightweight platforms.

More specifically, in the first part of this seminar, I will discuss recent advances in the concept of elastic Bound states In the Continuum (BICs), an intriguing class of modes that remain perfectly localized despite coexisting with a continuum of radiative states. These BICs offer a powerful mechanism for achieving infinite quality factor resonances, which are particularly promising for enhancing sound and vibration absorption and for developing highly sensitive sensors.

In the second part of the seminar, I will introduce the emerging concept of phononic skyrmions, topologically nontrivial configurations in elastic fields that mimic their magnetic counterparts. These phononic structures open exciting opportunities for encoding and transporting vibrational information in robust, reconfigurable ways, potentially paving the way for the applications related, for example, to acoustofluidics and microfluidics.

Biography:

Professor Badreddine Assouar received his PhD degree in Materials Physics from Nancy University in France in 2001. In 2002, he became a Research Scientist at “Centre National de la Recherche Scientifique (CNRS)” in France. He obtained his habilitation to supervise research (HDR) in 2007 and became a Research Professor. In 2010, he joined Georgia Institute of Technology in USA as visiting Professor, where he spent 2 years, developing researches on metamaterials. He afterwards founded the “Acoustics Metamaterials and Phononics” group at the University of Lorraine where he is developing researches on acoustic/elastic metamaterials, metasurfaces, phononics and wave physics. He is currently a Director of Research at the CNRS, and since 2021 the Director of the LabCom MOLIERE, a joint industrial-academic research unit focused on innovative functional materials for aeronautics. In 2024, Prof. Assouar has been elected a Fellow of the European Academy of Sciences. He is also serving as Associate Editor with Physical Review Applied since 2019.

Professor Assouar is author or co-author of more than 165 international peer reviewed publications, in leading international journals including, Phys. Rev. Lett., Nature Review Materials, Advanced Materials, Nature Communications, Science Advances, Phys. Rev. Applied …, and more than 50 invited talks and keynotes over the world. This has led to highly recognition of his works and achievements over the past 20 years, as indicated by the high citations rate his works has collected (11000 citations, and h-index of 59).

ALL INTERESTED ARE WELCOME