BIOSKETCH: “Togolese-born, I have started my post-baccalaureate training program in Civil Engineering field at National Superior School of Engineering (ENSI-TOGO). I have finished my training program by a Master degree at National Engineering School of Metz (ENIM-France) with focus on Mechanics, Materials, Structures and Processes. With this training, I acquired a good scientific formation which makes me able to begin a PhD in Solids Mechanics.
Currently, I’m working as ESR on “Development of necking instabilities in anisotropic ductile plates subjected to dynamic loading” in the OUTCOME project. My application for this project is motivated by my desire to make a good scientific career. OUTCOME brings together several academics and industrials partners, it’s a good opportunity to forge a rewarding experience through work in several labs in different towns and with well-known professors.”
- MCAA conference: Espoir will attend to the 2017 MCAA Conference and General Assembly that will be held on 24th and Saturday 25th March 2017 in Salamanca, Spain. The ESR will present a poster to show his current scientific progress and show the scope of his research (link here).
- Seminars UC3M: Espoir has attended to the seminars that Professors Miles B. Rubin from the Israel Institute of Technology (Israel) and Katarzyna Kowalczyk-Gajewska from the Institute of Fundamental and Technological Research of the Polish Academy of Sciences (Poland) have delivered during their respective research stays in the UC3M.
- Scientific data base course: Espoir has followed a training course delivered in the UC3M on the use of the scientific data base Scopus. The ESR learnt about all the functionalities of this tool including different ways to present and search for information, scientific papers, authors (link here) in November 2016. University Carlos III of Madrid (Leganés, Madrid, Spain).
- “As part of my training activities, I have attended a Scopus training in November 2016. As a basictraining, the formation was focused on Scopus basic features. It was very interesting and useful. It helps me to search for specific papers, create a bibliography….”
- Spanish course: Espoir will follow the second semester of the academic year a Spanish course specific delivered by the UC3M for foreign students and professors willing to learn or improve their knowledge of Spanish (link here).
“I have been working at UC3M (Universidad Carlos III de Madrid) for almost 4 months as ESR in the OUTCOME Project and my heart is full of joy.
The city is beautiful, vibrant and full of wonderful places to discover. There are a lot of things to experience. I hope to try most of them.
Besides my supervisor, “mi Amigo”, I’m surrounded by nice people in the Lab. The work atmosphere is pleasant and the ambience in the department is superb and warm.
About the PhD topic, I like it! It is quite challenging and I’m never bored. I receive the proper assistance and support from my supervisor. Currently, we are dealing with the analytical part of the thesis. We are planning to investigate several thematic and slowly but surely, we keep moving ahead. Broadly speaking, the PhD deal with plastic instabilities. At the end, I would like to gain valuable experience in both theoretical and numerical analyses of necking instabilities. Some experiments will be performed during the thesis, and this will provide me with the experimental insight of plastic instabilities.
Concerning the Spanish, It sounds like poetry to me and I want to learn it. So, in the near future, I will have a few courses in the University.”
So far, my research works are focused on the analytical part of the thesis. 1D and 2D stability models
are developed for the analysis of necking instabilities in rods and plates. Numerical simulations have been performed through a collaboration that we have initiated with professor Ankit Srivastava, from the Texas A&M University (USA). These research activities can be detailed as follows:
- Analysis of multiple necking in porous rods during dynamic stretching Two approaches have been used for that task, namely linear stability analysis and finite element calculations. The linear stability analysis has been carried out in 1D framework and the GursonTvergaard-Needleman (GTN) constitutive law has been used. The model accounts stress multiaxiality and inertia effects. The finite element calculations have been performed using an axisymmetric finite element model. The initial void volume fraction is fixed in the calculations. The varying parameters are the applied strain rate, the random number seed which pilot the voids dispersion in the rod and the amplitude of the porosity which pilot the variation in porosity at a material point. The stability analysis results have been compared to the results of the finite element calculations and it can be concluded that the localized necking strain and the spacing between necks are well predicted by the perturbation model. Moreover, it has been brought to light that localization is not triggered in the configuration when voids are homogeneously dispersed in the rod. It has also been shown that localization depends barely on the configuration of voids dispersion.
- Multiple necking bands in biaxially stretched plates 2D perturbation model has been developed for the analysis of necking bands in anisotropic ductile plates subjected to dynamic biaxial tension. Further investigations are being done to shed light on how does the inception and the development of plastic flow localization are affected by anisotropy and the strength differential effects. The validation of analytical model will be done by finite element calculations, therefore stress integration algorithm is being developed for the purpose of implementing the material criterion of yielding into Abaqus/Explicit.