Multiscale simulations in crystalline materials are based on 3D Discrete Dislocation Dynamics (DDD) investigations.
When needed, atomistic information provided by Molecular Dynamics (MD) are introduced as local rules in the DDD modeling.
At the upper scale, DDD simulations can estimate parameters of constitutive equations in crystal plasticity Finite Element (FE) models.
At the continuum scale, cavitation erosion is investigated using classical FE models and Smoothed Particles Hydrodynamics (SPH) simulations. Both models account for the fluid/structure interaction.
In collaboration with Université Catholique de Louvain-La-Neuve, we are working on the role of interfaces in plasticity. The effect of the grain shape on the back stress induced in a single closed grain has been investigated in order to implement the microscopic features in a continuum description of the plasticity. Slip transmission and dislocation interactions between different grains of polycrystalline aggregates are also investigated for different orientations of the grains.
Cavitation erosion occurs when multiple bubbles collapse near a solid surface. During the bubble collapse, a fast reintrant jet impacts the surface and creates a deformation pit.
An inverse method has been conducted in order to estimate the aggressiveness of the flow from the observation of the pits printed on the surface in the first moments of the cavitation erosion. Assuming that each pit was generated by a single bubble collapse whose pressure field is treated as a Gaussian shape, finite element calculations are used for estimating the load that created each residual imprint. It is shown that the load distribution falls on a master curve independent of the tested material; the softer material (aluminum alloy) measuring the lowest impacts while the most resistant material (duplex stainless steel) provides access to the largest impact pressures.
mise à jour le 16 janvier 2019