Earthquakes can be devastating, both in terms of human and material damage. Although their existence has been known since the dawn of time, the physics of earthquakes is still poorly understood. Natural faults and earthquake characteristics are known to follow scaling power-law. The origin of this phenomenon has strong implications on the physical mechanisms driving slip events. However, it is not yet clear. The emergence of complexity can be related to the disorder of the system. Understanding if the observed complexity comes from the inherent complexity of the frictional motion or the system’s complexity is essential to better understand – and one day eventually predict – earthquakes. It has been shown numerically with a simple system without any disorder that resulting slip events follow a power-law distribution for the small events – like natural slip events – and a log-normal distribution for the larger ones. This project aims to study how adding disorder in this simple system will influence the transition between the power-law and the log-normal distribution of slip events. To do so, the student will use a finite element software developed in the lab (Akantu).
Supervisors:
Ferry Roxane Mathilde Suzanne, Jean-François Molinari
Extreme loads on solids lead to the formation of a multitude of cracks that propagate, branch and coalesce to form fragments. This process is called dynamic fragmentation. This process is of importance in many domains of engineering, where it is fundamental to predict the outcome of high velocity impacts or explosions. Often, one would like to extract statistics such as fragment size distribution. This project will feature experiments on object breaking into pieces to extract experimental statistics on fragments. The student will then use a finite element software (Akantu) to simulate crack propagation using different methods such as phase-field modelling of fracture or cohesive elements. The statistics obtained numerically will be compared to the experimental ones to highlight the advantage and limitations of the different simulation methods.
Supervisors:
Thibault Ghesquière-Diérickx, Shad Durussel, Jean-François Molinari
The impact of a drop on a solid surface is a canonical problem in fluid mechanics of fundamental significance in numerous natural and industrial processes, such as ink-jet printing, aircraft icing and spray cooling. Recently we found out soft solids display a similar behavior when colliding with a rigid surface. Namely, the contact is not made on the tip, but on an annular radius, with air trapped in between. This project will explore the scenario of highly viscous droplets and soft solids impacting on each other. The student will use the finite element software (Comsol Multiphysics) to simulate the dynamics using knowledge of both fluid and solid mechanics. Depending on the interest of the student the project will focus either on full 3D simulations to capture symmetry breaking or on axisymmetric ones to investigate the feasibility of using level-set or phase field simulation for droplet-air interface.
Supervisors:
Jacopo Bilotto, Jean-François Molinari
Granular materials play a critical role in civil, chemical, and mechanical engineering, influencing sectors such as food processing, pharmaceuticals, soil mechanics, and mixing technologies. The Discrete Element Method (DEM) is a powerful tool for simulating the behavior of particle systems by applying Newton’s laws of motion and friction. However, one significant limitation of DEM is its ability to accurately model materials that undergo large deformations.
To address this challenge, a recent reduced-order model, developed by Professor Mollon, offers an innovative approach to extend traditional DEM codes into the deformable regime. This project aims to evaluate the feasibility and stability of this novel method.
The student will implement the model using Python, leveraging the Taichi and NumPy libraries to efficiently code the method and test various interaction laws. Depending on the student’s interests, the project can be tailored to focus on either high-performance GPU computing or the mechanics of specific test cases.
Supervisors:
Jacopo Bilotto, Jean-François Molinari
