Mechanics, Structure & Energetics Laboratory (LMSE)

The research program initiated by the "Valorisation des Ressources Énergétiques" team focuses on composite materials with high latent heat of phase change for thermal energy storage at low and medium temperatures. The work involves using finely powdered matrices of mineral, vegetable or animal origin and impregnating them with a molten phase-change material (PCM). Cold compression is also applied to the composites to improve their volume storage capacity. The composites selected after characterization of chemical, thermal and physical properties (DSC, FT-IR, SEM, Laser Granulometry, ATG...) can be tested in building walls to improve thermal comfort or for other thermal applications. Six doctoral theses have been initiated on this theme, three of which have been completed (finalized and defended in 2019), while three others are in progress. At the same time, every year, Master's subjects are launched on projects involving thermal storage (solar air collector with thermal storage, solar hot water collector with thermal storage, parabolic trough collector with storage, solar concentrator with storage). The research team also deals with solar distillation. The research team is also working on convection in a semi-open environment, solar drying and solar distillation. Three doctoral theses have been undertaken, one of which has been completed (defended in 2019), while the second is in its final phase (dissertation to be defended in 2021).

Miss Djefel Dihia, who defended her doctoral thesis in July 2019, has been recruited and joined our laboratory as a researcher to prepare for her habilitation. Heat storage applications followed by validation tests are envisaged for the continuation of Ms. Djefel Dihia's thesis work. Ms Khedache Souad, who also defended her thesis under the supervision of Pr Makhlouf Said, has joined our research team as a researcher as part of her university habilitation. Tests on walls equipped with latent heat storage systems will be initiated to validate her future work. In addition, Ms. Boussaba Lisa (architect by training), a doctoral student who worked under my supervision on improving thermal comfort in buildings, defended her thesis in February 2020. This work has been the subject of several publications, and further work is planned as part of her habilitation. Following the first phase of development, characterization and validation of the new composites, prototypes are currently being built to introduce the selected composites into a structure. Flux and temperature measurement tests will be carried out, and simulation models are being developed. The results of these simulations will be compared with the results of the measurements carried out to validate them. This part of the project has been completed for Ms. Khedache Souad and Ms. Boussaba Lisa, and articles are expected. PhD student Dahmous M'hand architecte (under the supervision of my collaborator Lamrous Nacer) has finalized his development and characterization work. An experimental prototype (prefabricated wall with energy storage) has been assembled and tests on a test cell are underway. In addition, the prototypes produced as part of the Master's projects (parabolic trough collector with energy storage, solar distiller with energy storage, air collector for solar drying, etc.) will undergo further testing. Finally, a new doctoral thesis in Architecture has been launched, focusing on the introduction of new composite materials with high latent heat of phase change to improve thermal comfort in the Saharan climate. The doctoral student involved, in collaboration with Ms. Foufa Abdessalem of Blida University, is Ms. Dahmani Kamélia. Her thesis is in progress. The development phase is well advanced, with physicochemical and thermal characterization still to be carried out in order to select potential candidates for a thermal storage operation applicable initially to a prototype to be designed.

Full list of permanent team members

Complete list of doctoral students in the team

The interaction of particulate radiation with living or inert matter is undoubtedly one of the most important areas of research, given its many applications in various fields: These include medical imaging, radiobiology, biology, plasmas, condensed matter, the environment, etc. The aim of this work is the theoretical and experimental study of phenomena linked to the effects of irradiation of living or inert matter by charged particles (electrons, positrons or ions). In the theoretical part of the problem, we develop analytical and numerical calculations based on the models considered, in order to determine the differential and integral cross-sections of elastic and inelastic scattering, such as the double ionization of the molecules making up the material under consideration. In concrete terms, we subject molecules making up DNA (adenine, guanine, thymine, purine etc.) or inert molecules (HCl, H2S, HF, PH3, NH3 etc.) to electron beams of different kinetic energies, and study simple elastic and/or inelastic scattering reactions such as double ionization by calculating multi-differential and integral effective cross sections. In this way, certain physical characteristics of the materials considered will be elucidated. The experimental part of the project is carried out in cooperation with partners abroad. We are bombarding samples of a given material and its oxides with 5 keV Krypton ion beams. The surfaces are then sputtered, and the ejected species (sputtering products), in excited states, de-excite and emit radiation. We measure the intensity of these emissions and their energies. These measurements enable us to identify the electronic states involved. Quantitative and qualitative analyses provide access to the characteristics of these materials, and identify impurities deposited on the surfaces of the samples analyzed.

The theoretical part of the research project developed within our team is currently focused on the development and application of the analytical method on the adenine, guanine, thyminine and cytosine molecules that make up the DNA bases, of proven interest in radiotherapy. We first write the analytical expressions for the multiply differential and integral cross sections of the elastic scattering of electrons of different impact energies in the (PW2C) model, taking into account the fine effects of the interaction potential, such as correlation-polarization and exchange. Subsequently, we write the numerical codes to actually start the calculations. On the experimental side, work has begun on the angular distribution of particles sprayed from the surface of ternary Fe71:9Cr5:6Al22:5 alloys under ^Kr+ ion bombardment at normal incidence.

Full list of permanent team members

Modal and parametric identification of structures. Dynamic substructuring. Defect localization. Reanalysis of mechanical structures.

This study concerns the identification and monitoring of dynamic structures, whether linear or non-linear, homogeneous or complex. The research envisaged for the different cases of structures is threefold: modeling, predictive calculation of their dynamic behavior, damage detection-localization and monitoring of mechanical structures. The structures considered may be subjected to impulse, harmonic or random excitation.

The planned research work is divided into four parts:

1.  the first part concerns the identification of the mechanical characteristics of dynamic structures with low or high levels of non-linearity. Non-linearities can take various forms: contact and friction non-linearities, geometric and material non-linearities, etc. The practical interest of this study is to generalize methods for identifying linear structures to the case of non-linear and composite structures.
2.  The second part deals with the identification, quantification and localization of damage in dynamic homogeneous and composite structures with low or high non-linearity. The aim is to develop new damage indicators and analyze their performance. In particular, the aim is to develop a damage indicator that reflects the pseudo-damage induced by any damage to a multilayer composite structure.
3.  The third part concerns the optimization of composite mechanical structures.
4. The fourth part concerns the dynamic identification of composite sandwich structures for use in shock absorption. The aim is to find lightweight, high-strength mechanical structures which, under the effects of an explosion, can absorb the effects of the shock wave and redirect the overpressure towards a controllable mouth.

 Research in progress:

Each member of the team is dedicated to one of the following themes:

•  Generalization of the team's previously established methods for identifying linear structures to the case of non-linear and composite structures.
• Development of new structural damage indicators. In particular, the aim is to develop a damage indicator that translates the pseudo-damage induced by any damage to a multi-layer composite structure.
• Optimization of composite mechanical structures: the aim is to find lightweight, resistant mechanical structures that better meet specifications in terms of cost and reliability of dynamic behavior.
• Dynamic identification of composite sandwich structures for use as shock absorbers. The aim is to find lightweight, high-strength mechanical structures that can absorb the effects of an explosion and redirect the excess pressure towards a controllable mouth.

Full list of permanent team members

Complete list of doctoral students in the team

Effect of thermomechanical treatments on the microstructure and physicochemical properties of metals and alloys. Stability of rotating flows. Optimization of thermomechanical material parameters. The research team is interested in :

1) Metal-solution interaction

When the metal is in direct contact with an oxidizing liquid or gas, whether moving or not, charge separation at the interface is also observed, depending on the solid's electronic properties, adsorption and sorption chemistry. Forced convection and magnetic fields induce complex interfacial phenomena. Convection increases the displacement of electro-active species towards the metal surface, while the effect of the magnetic field remains its final response.

For this point, we are interested in the effects of low and medium intensity permanent magnetic fields on the quality of oxide films and deposited layers.

2) Flow study

The first part of this study involves injecting solid particles into a flowing fluid in a pipe and observing the resulting phenomena. Particle-wall and fluid-wall contacts can give rise to corrosion phenomena, which are the main cause of surface deterioration, or deposition phenomena, which can be beneficial. In the second part of this section, we look at the phenomenon of particle deposition in a porous medium. In this part, the effect of the heterogeneity of the porous medium on the phenomena of particle transport and deposition will be highlighted. Since energy efficiency is a key issue, the final section will focus on minimizing energy consumption in the various systems.

Key words

Corrosion, magnetic fields, aluminum alloys, stainless steels, thermomechanical treatments, metal texturing, fluid-structure interaction, flows, porous media, fluids, energy. 

Study of the corrosion behavior of the AlSi10Cu(Fe) alloy casting surface and the effects of a low-intensity permanent magnetic field on the electrochemical noise and corrosion of aluminum-silicon alloys. The effects of the ECAP process at 90° and 120° angles on the micro-hardness, texture and corrosion behavior of aluminum alloy AA1370 wire. Effects of alumina particle size and fraction on the corrosion behavior, microstructure and texture of an aluminum-alumina composite, corrosion of stainless steels used as implants in a blood-simulating medium. Supervision of ten doctoral theses, co-supervision of two doctoral theses by another member, supervision of several Master's theses by team members. Participation of five team members in the opening of a doctoral training program. Participation of one member in a PRFU project. Participation of two members in a national mobility project (mobility research project ATRST 15/2018). Several national and international communication projects.