Description of the thesis topic

As part of the ANR AMESDEP project, conducted in collaboration between ICA Toulouse, I2M Bordeaux, and IMT Nord Europe, we are offering a thesis topic in the field of composite materials. The AMESDEP project aims to study the impact of defects and draping singularities resulting from the manufacturing process on the thermomechanical damage and permeability of thermoplastic composites used for liquid hydrogen storage.
With the energy transition, type 4 or 5 composite material tanks represent a key solution for vehicles requiring high-density energy storage. However, the removal of the liner in these tanks (type 5), with a view to reducing mass, makes it crucial to control the permeability properties of composites. The thesis project focuses on specific defects induced by automated fiber placement (AFP), in particular gaps and overlaps, which can affect the mechanical properties and promote the initiation of cracks in these materials, thereby modifying the permeability of the tank. It should be noted that, to date, little work has been done to explore the effect of these defects on the multiphysical behavior of composites in cryogenic environments.

The thesis topic is structured into three main parts.
• The first part focuses on the influence of AFP process parameters on defects generated during the manufacture of thin and thick plates. A multi-scale analysis of these defects will be conducted, using X-ray tomography and scanning electron microscopy (SEM) in particular.
• The second part focuses on analyzing the impact of AFP process parameters on residual stresses developing in flat and curved plates, the latter being representative of the geometry of a storage tank. To do this, embedded instrumentation using fiber Bragg gratings (FBG) will be implemented.
• The third and final part aims to establish the link between manufacturing defects, residual stresses, and the mechanical behavior of composites, both at room temperature and in a cryogenic environment.

The results obtained in this project will contribute to advancing knowledge about the relationship between the implementation of thermoplastic composites and their behavior under extreme conditions. They will also enable recommendations to be made for the manufacture of low-permeability cryogenic tanks.
Keywords: AFP process, manufacturing defects, severe behavior, residual stresses

Skills developed:
• Collaborative work, communication
• Creativity and innovation
• Composite manufacturing process and multi-instrumented mechanical testing

Required profile:
Master's degree/Engineer in Mechanical Engineering, Materials Mechanics. The candidate must have a taste for experimentation and collaborative work. Knowledge and/or experience in manufacturing and mechanical testing instrumentation would be highly appreciated. Autonomy, rigor, and initiative will be necessary for the success of the project.

Work Context

Clément Ader Institute (ICA, CNRS UMR 5312).
The ICA is a research laboratory dedicated to the study of mechanical structures, systems, and processes. Our areas of activity are in line with those of the mechanical engineering industry, with a particular focus on projects in the fields of aeronautics, space, transportation, and energy. Our work generally focuses on behavior modeling, instrumentation, and the study of the durability of the structures or products in question. A significant part of our research focuses on composite materials, which now play an important role in structures.

The ICA brings together around 80 teacher-researchers, 20 temporary researchers, 20 BIATSS staff, 90 doctoral students, and numerous interns. It is unique in that it includes:
- in terms of supervision, staff from four major institutions: UPS and INSA from the Ministry of Higher Education and Research, ISAE from the Ministry of Defense, and Mines Albi from the Ministry of Industry;
- in terms of geography, staff spread across four cities in the Midi-Pyrénées region: Albi, Figeac, Tarbes, and Toulouse.
The management team consists of a director and two deputy directors, with the three supervisory ministries represented in this trio. The technical support team (BIATSS staff) is organized into three components, one for each ministry.

The laboratory is organized into four research groups:
- MSC Group: Composite Materials and Structures
- SUMO Group: Surface, Machining, Materials, and Tools
- MS2M Group: Modeling of Mechanical Systems and Microsystems
- MICS Group: Metrology, Identification, Control, and Monitoring

This thesis work falls within the research themes of the MSC group, and more specifically the MaPP axis: Materials – Processes – Properties.

The position is in a sector covered by the protection of scientific and technical potential (PPST) and therefore, in accordance with regulations, requires your arrival to be authorized by the competent authority of the MESR.

The position is part of the ANR AMESDEP project, conducted in collaboration between ICA Toulouse, I2M Bordeaux, and IMT Nord Europe.

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.

Constraints and risks

XRD measurements

Additional Information

N/A