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Sujet de stage / Master 2 Internship

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Dynamic fracture in glass: development of experimental setup & protocol

Contact: ROUNTREE Cindy, , cindy.rountree@cea.fr, +33 1 69 08 26 55
Summary:
Development of potential drop method on oxide glass samples.
Possibility of continuation in PhD: Oui
Deadline for application:29/03/2024

Full description:
One of the most important materials today is glass, as such the United Nations Declared 2022 the International Year of the Glass (IYOG). IYOG2022 was not only to celebrate the importance of glass’s impact on our history, but also to usher in the Glass Age. In this new age, glasses will need to maintain their advantageous properties (transparency, hardness, low thermal expansion, high melting point temperature, relative chemical inertia, etc.), while also overcoming its major weakness: fragility. Relatively moderate stresses can cause glasses to break suddenly. These types of failures are typically associated with dynamic fracture, where a crack front propagates on the order of the speed of sound, i.e. 1 km/s in Plexiglas, and up to 3 km/s in oxide glass (window glass). Despite being well-known, quantifying and capturing a crack front’s movement in real time remains a challenge. For example, traditional techniques (such as rapid imaging) are not suited for these spatio-temporal scales, let alone other high speeds failure issues, including fragmentation under impact and why glass breaks into a thousand pieces and not two!

A promising technique to capture the dynamics of crack front at the relevant spatio-temporal scales is the potential drop method. This involves depositing thin strips (a few tens of nanometers) of metal on the sample surface. Subsequently, these strips are attached to an oscilloscope which empowers us to capture the precise time and position (on the scale of a few tens of nanoseconds and nanometers) at which one of the metal strips break as the crack propagates through the sample. This method has been successfully used on PMMA samples. The challenge herein is to extend the potential drop method to oxide glass samples (stiffer and smaller).

In this regard, the intern will have the unique opportunity to setup and qualify the experimental methodology applied to glasses. The intern will be responsible for:

• Designing the strip geometry and associated electrical circuit;
• Carry out metal deposition in a clean room;
• Perform dynamic fracture experiments;
• Analyze and interpret the signals obtained;
• Qualify the method in relation to the literature and known data on fracture.

The intern will be an opportunity to work with SPEC-SPHYNX researchers on the mechanical behavior of glass. SPEC is a joint CEA / CNRS unit (UMR 3680 CEA-CNRS) carrying out research into the condensed state, ranging from quantum technologies to fracture physics. In particular, it has a state-of-the-art clean room and various experimental platforms. In this context, the candidate will have the opportunity to manipulate theoretical and experimental tools used in the fields of materials science, mechanics and fracture physics.
Technics/methods used during the internship:
Clean room, AFM, Traction machines, etc.

Laboratory
Tutor of the internship

 

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