BIOSKETCH: “Born in TOGO, I studied physics at the Faculty Of Sciences at the University of Lomé-TOGO. Being graduated, i have decided to apply for a master degree in Mechanics, Materials, Structures and Processes at the University of Lorraine (Metz-FRANCE). I got the master degree in Metz this year 2016. During my studies, I have acquired a solid background in the field of physics and mechanics of materials, so with these skills, I’m well prepare to start a Phd Thesis.
Currently I am working as ESR on “Modeling of delamination and strength in interface printed circuit boards” in the European Marie Sklodowska Curie project OUTCOME. The Phd subject is proposed by a SME, Cimulec PCB manufacturer and the LEM3 laboratory at the University of Lorraire. This european program provides me full of opportunities for exchanges. I will deeply increase my knowledges by the interactions with various academic and industrial partners . This program offers a very good starting point for my future career as researcher.“
- Welcome days: Essossinam attended 2 welcome days organized by difference academic entities of the University of Lorraine where he obtained basic information about the resources at his disposal as member of the University.
- Welcome day for the new Phd students of the lab: University of Lorraine on November 23, 2016 in Metz.
- Welcome day meeting organized by the EMMA doctorate school: November 17, 2016 in Nancy.
- Technical training courses: Essossinam is currently following (or will follow in the near future) technical courses on different aspects of solid mechanics:
- Course on Characterization of Materials under Dynamic Loading. October 2016 – January 2017. 20 hours.
- Course on Experimental Methods in Solids Mechanics. October 2016 – January 2017. 20 hours.
- Course on Numerical Methods in Mechanics of Deformable Solids. March 2017. 20 hours.
- Training day on experimental techniques: Performing peeling tests. MTS headquarters. 15th December. Paris.
- Non-technical courses and activities: Essossinam is also following non-technical courses to complement his training:
- Training First-aid worker (SST). December 2016 – Certificate received December the 12th.
- How to find a job after the PhD? Organized by the UL. 7 February – Nancy.
- How to promote skills developed during the PhD? Organized by the UL. 23-24 February – Nancy.
“My Phd is advancing well in Metz (France). I started the digital side of my research. I expect this phd to be very knowledgeable in scientific application. On a professional level, I would like this thesis to help me find work in a company or in a research laboratory. I am very proud to make this thesis in project OUTCOME.”
In a first time, I read the theory of peeling for different kind of materials. Then, i have continued my research activities by developing first elementary numerical simulations and first experiments on peeling.
In the literature, it is confirmed that cohesive elements is well adopted for delamination process. Therefore, I understood how to use cohesive elements as interface between the thin film and a rigid substrate and how to use them in numerical simulations. Naturally, the behavior of cohesive elements needs some parameters to be calibrated so i will be have to identify based them on the proposed and dedicated experiments on peeling. From the numerical point of view, I develop peeling finite element model (elastic nylon thin film bonded on a rigid substrate) considering three different peeling angles (60, 90 and 120 degrees). The results I got from those simulations are in agreement with the theory of peeling proposed in the literature for elastic thin film. Indeed, I was able to recover the fact that when the peel angle increases, the peel force decreases. I also verified that the critical decohesion energy per unit area is a constant whatever the angle.
In parallel, I have also begun the experimental part of my research activities with the new peeling machine in LEM3. I received a two days training on this peel test equipment. CIMULEC provided me specimens for the first tests. I checked also that experimental results are in agreement with the literature ie the peel force decreases when peel angle increases. For my phd, we mainly focus on a two material configuration: thin film of copper bonded on rigid (or elastic) substrate (woven composite material).
For the next period, I have to investigate the following aspects. In the numerical simulation I will introduce the plastic behavior of the copper and compare my result with previous works in literature. I will try to develop experimental devices for high temperature (100 to 150 °C) and in low temperature regime to see the effect of the ambient temperature on the adhesive property. It is expected that a change in the peel strength can be measured so the peeling test device will be able to measure this evolution.
In January I spent in CIMULEC two weeks training about the manufacturing of printed circuits boards (PCB). I discovered in deep details all the process to make a PCB. Cimulec offers me the possibility to understand problems they encountered. I understood that the prediction of delamination needs a specific characterization of the mechanical behavior of the layers but also needs the development of an experimental set up dedicated to the PCB applications.