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2025年巴黎高科 - CSC合作公派读博项目 - 课题No.54
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2025年巴黎高科 - CSC合作公派读博项目 - 课题No.54 2025 巴黎高科 - CSC公派博士项目 （12月8日截止） 网申通道：https://paristech.kosmopolead.com/phd 申请攻略：https://paristech.fr/fr/paristech-csc-phd-program-how-apply 课题54详情: TITLE: ELASTOGRAPHY AND ULTRASONIC IMAGING IN SOFT GRANULAR MATERIALS Topic number : 2024_054 Field : Material science, Mechanics and Fluids Subfield: Applied Physics, Acoustics ParisTech School: ESPCI Paris - PSL Research team : Materials, resonances and interfaces (MRI) Research team website: https://www.institut-langevin.es ... ances_and_interface s_mri Research lab: Institut Langevin Lab location: Paris Lab website: https://www.institut-langevin.espci.fr Contact point for this topic: xiaoping.jia@espci.fr Advisor 1: Xiaoping Jia - xiaoping.jia@espci.fr Advisor 2: Arnaud Tourin - arnaud.tourin@espci.fr Advisor 3: Jean-Luc Gennison - jean-luc.gennisson@u-psud.fr Advisor 4: Short description of possible research topics for a PhD: Understanding the microscopic origin of behavior in particulate and particle-fluid systems such as granular materials, foams, and emulsions is of both practical and fundamental importance. In this PhD project, we will investigate the mechanical behavior of an assembly of immersed gel beads (isodense) by ultrasound imaging (transient elastography) and rheology [1,2]. Studying such a soft granular material or suspension is of interest not only for biomedical applications (muscles and tissues) and for geophysical implications (landslides) [3], but is also relevant to the physics of complex systems where the transition from a liquid state to a solid state [4] remains a highly topical issue. In this work, we will first use an ultrafast ultrasound scanner to monitor the low-frequency shear wave within an optically opaque dense gel bead packing generated by an oscillating plate (Fig. 1). We will be particularly interested in nonlinear response such as shear elastic softening and fracture dynamics [1] as a function of shear amplitude (Fig. 2a). Such transient elastography was originally developed in our laboratory to track tissue motion induced by low-velocity shear waves in the context of medical imaging [2]. In addition, we will use steady and oscillatory shear rheological measurements (Fig. 2b) [5] combined with ultrasonic imaging to monitor the structure change due to plastic rearrangements of particles. Especially, we will investigate the effects of particle shape (e.g., granular dimers/trimers) and/or anisotropic behavior (i.e., force chains) in response to external loading [6]. In the long-term, this research is linked to the search of a possible system for producing artificial skeletal muscles whose mechanical properties can be modified and produce the desired force to dissipate the mechanical energy of an external impact. Inspired by a proposal from Pierre Gilles de Gennes [7] who exploited a temperature-driven nematic/isotropic phase transition to induce a sudden contraction in an artificial muscle, we will also investigate the possibility to modify these soft particle networks by controlled acoustic perturbations. This work will be carried out at the Langevin Institute, ESPCI Paris-PSL, in collaboration with Dr. Jean-Luc GENNISSON at the Laboratoire d'Imagerie Biomédicale Multimodale at Paris-Saclay University. [1] J. Brum, J.-L. Gennisson, M. Fink, A. Tourin & X. Jia, “Drastic slowdown of the Rayleigh-like wave in unjammed granular suspensions”, Phys. Rev. E 84, 020301 (2019) [2] S. Catheline, J.-L. Gennisson, M. Tanter, and M. Fink, “Observation of shock transverse waves in elastic media”, Phys. Rev. Lett. 91, 164301 (2003) [3] P. Johnson and X. Jia, “Nonlinear dynamics, granular media and dynamic earthquake triggering”, Nature 437, 871 (2005) [4] A. J. Liu and S. R. Nagel, “Jamming is not just cool anymore”, Nature 21, 396 (1998) [5] J. Léopoldès and X. Jia, “Probing intermittency and reversibility in a dense granular suspension under shear using multiply scattered ultrasound”, Soft Matter (2020), DOI: 10.1039/D0SM01427C [6] M. Z. Miskin and H. M. Jaeger, Adapting granular materials through artificial evolution”, Nature Materials 12, 326 (2013) [7] P. G. de Gennes, “A semi-fast artificial muscle”, C. R. Acad. Sci. Paris 324, 343 (1997) Required background of the student: The student should have a good background in physics, particularly in acoustics and mechanics. The management and interpretation of images generally use the MATLAB and /or Python language with which the candidate should be familiar. A list of (5 max.) representative publications of the group: (Related to the research topic) 1. J. Brum, J.-L. Gennisson, M. Fink, A. Tourin & X. Jia, “Drastic slowdown of the Rayleigh-like wave in unjammed granular suspensions”, Phys. Rev. E 84, 020301 (2019) 2. P. Johnson and X. Jia, “Nonlinear dynamics, granular media and dynamic earthquake triggering”, Nature 437, 871 (2005) 3. J. Léopoldès and X. Jia, “Probing intermittency and reversibility in a dense granular suspension under shear using multiply scattered ultrasound”, Soft Matter (2020), DOI: 10.1039/D0SM01427C |
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