I am currently Full Professor in Mechanics (section CNU 60) at the d'Alembert Institute of the Université Pierre et Marie Curie, Equipe MISES.
You find below an overview of my research activities.
Available Fundings
- Ph.D Thesis and Postdoc on Fracture of Heterogeneous Media.
Research topics
Damage and fracture mechanics
Collaborations: Jean-Jacques Marigo (LMS, Ecole Polytechnique), Blaise Bourdin (Louisiana State University),
Jean-Francois Babadjian (UPMC),
Duvan Henao (Pontificia Universidad Católica de Chile),
Véronique Lazarus (Paris 11),
Georges Gauthier (Paris 11),
I study fracture and damage of brittle materials in the framework of the variational approach to fracture mechanics
proposed by Francfort and Marigo (JMPS 1998).
Current results include the extensions of the orginal approach to account for unilateral contact effects at crack lips
(JMPS09), the crack propagation by fatigue effect, complex crack patterns induced by thermal shocks,
thin film fracture and delamination .
You find here
here
some free codes to solve the problem of variational fracture and damage models using FEniCs
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Transverse fracture (red) and debonding (shadow) of a thin film bonded on a substrate and submitted to thermal loads ( Leon Baldelli's PhD Thesis). |
Cracks of vynil stickers at Ecole Polytecnhique ( Leon Baldelli's PhD Thesis). |
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3D crack pattern induced by a thermal shock showing the nucleation and selective propagation of a network of almost hexagonal cells. Numerical simulation using a gradient damage model and a parallel finite element code (44 millions elements). In collaboration with Blaise Bourdin, Paul Sicsic and Jean-Jacques Marigo. Color code: crack depth. |
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Fracture with unilateral contact of a pinned plate. |
Fatigue crack in an asymmetric tearing test. |
Stability and multiple-parameter actuation of morphing beams and shells
Collaborations: Stefano Vidoli (Univ. of Rome La Sapienza), Amâncio Fernandes (UPMC), Joël Pouget (UPMC), Angela Vincenti (UPMC)
Beams, arches, plates, and shells may exhibit several stable equilibrium configurations very different in shape because of geometrical non-linearities. These properties attract the interests of the engineering community to conceive multistable structures able to keep without an external actuation several equilibrium shapes, each one associated to a specific functional regime (morphing or shape changing structures). By means of simplified analytical models we investingate the effect on multistability of geometrical and material properties. Results are validated by finite element simulations. For example, we show that thank to the interplay between geometrical non-linear effects and material anisotropy, unifomely curved orthotropic shallow shell may show up to three stable equilibrium configurations (Proc. Royal Soc. A 464, 2949-2966, 2008). We are currently investigating how to effciently use multiparameter actuation provided by active materials (as piezoelectric fibers or shape memory alloys) to control the passage bewteen the different shapes of multistable plates and shells (IJSS10).
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Bistable buckled beam: stability diagram |
Tristability of orthotropic shallow shells |
You find below two interactive Mathematica demonstrators showing the stable equilibrium configurations of uniformely curved orthotropic shells as a function of the initial curvature and the material parameters (see Proc. Royal Soc. A 464, 2949-2966, 2008):
- Extensible model (File to open with Mathematica or the free Mathematica player)
- Inextensible model (File to open with Mathematica or the free Mathematica player)
Capillary deformations of soft hyperelastic solids
Collaborations: Serge Mora (Univ. Montpellier), Basile Audoly (UPMC), Yves Pomeau (Univ. Arizona).
Under the effect of surface tension a blob of liquid adopts a spherical shape when immersed in another fluid. We demonstrate experimentally that soft, centimeter-size elastic solids can exhibit a similar behavior: when immersed into a liquid, a gel having a low elastic modulus undergoes large, reversible deformations. 2e analyze three fundamental types of deformations of a slender elastic solid driven by surface stress, depending on the shape of its cross-section: a circular elastic cylinder shortens in the longitudinal direction and stretches transversally; the sharp edges of a square based prism get rounded off as its cross-sections tend to become circular; a slender, triangular based prism bends. These experimental results are compared to analysis and non-linear simulations of neo-Hookean solids deformed by surface tension, and are found to be in good agreement with each other (PRL13).
You may find here some animations.
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Deformations of soft almost incompressible hyperelastic rods with circular (compression) and triangular (bending) cross-sections under the effect of the surface tension when they are uniformely immersed in a fluid. The numerical simulations are obtained with a finite element code developed based on FEniCs (see this PRL paper and the related supplementary material). Color code: pressure field.
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Modeling and identification of piezoelectric structures
Collaborations: Joël Pouget (UPMC), Francesco dell'Isola (Rome/La Sapienza), Maurizio Porfiri (Polytechnic Intitute, New York)
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A beam with piezoelectric actuators |
Cross sectional distribution of normal transverse stresses for applied voltage |
Distributed passive vibration control by piezoelectric shunting
Collaborations: Francesco dell'Isola (Rome/La Sapienza), Maurizio Porfiri (Polytechnic Intitute, New York)
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Beam with distributed piezoelectric shunting |
Experimental setup |