Nombre total de résultats : 123
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S. Boukhezar, K. BEY, L. Alimi, S. BOUDIAF, M. Boulkra (2018)
Article de conférence

In order to improve the performance of Poly(methyl methacrylate)/glass fibers composite used in the fabrication of the prosthetic socket, we try to introduce powdered pits as reinforcements with Poly(methyl methacrylate) resin (PMMA) to form hybrid composite. The presented work consists, firstly, in optimizing the experimental parameters for the preparation of a PMMA / glass fibers composite loaded with organic particles. Then, Tensile strength (TS) tests were conducted to assess the mechanical properties of the prepared specimensVoir les détails

Mots clés : Prosthetic Socket, Hybrid Polymer Composites, mechanical properties, PMMA, Pits Date Powder

Determination of the elastic parameters of thermoplastic composites using the indentation technique

A. Mokhtari, N. Tala-ighil, A. Brick Chaouche, Y.A. MASMOUDI (2018)
Article de conférence

this work deals with the application of the macroindentation technique to the determination of the elastic parameters of composite with polypropylene matrix and reinforced with ductile and brittle fibers. The aim is to obtain a representatives average values taking into account the influence of the holding time and type of the used reinforcement (ductile or brittle reinforcement) on the overall elastic modulus of the studied polymers. To do this, the diameter of the indenter used ischosen relatively large (diameter of 16 mm) and the load equal to 6 kN. The various results obtained made it possible to see the effects of the holding time and the type of reinforcements used on the evolution of the elastic modulus of the reinforced compositeVoir les détails

Mots clés : thermoplastic composites, macro-indentation test, viscoplastic behavior

The influence of scale yielding conditions in the determination of the fracture load using both analytical and numerical approaches for the study of the elasto-static anti-plane problem of a crack in a semi-infinite strip containing a non-homogeneous zone

Article de conférence

The elasto-static anti-plane problem of a crack in a semi-infinite strip containing a non-homogeneous zone was studied using two approaches. The first one consist on an analytical approach based on the solution of a Singular Integral Equation (SIE formulation) using the Dugdale-Barenblatt cohesive model and the second approach is a numerical method based on a finite element analysis using a bilinear cohesive model (FEM-CZM approach). The results were expressed in term of fracture load. The length of the developing cohesive zone ahead of the crack tip was deduced at the crack initiation. This critical length size which was normalized with the crack size is taken as a characteristic length for defining the small/large scale yielding conditions of the particular studied case. For the small cohesive zone sizes (small scale yielding conditions), the computed values of the fracture load show a small difference between analytical and numerical approaches. In the other hand for the case of large cohesive zone sizes, the obtained values of the fracture load show significant discrepancy between the two approaches.Voir les détails

Mots clés : Crack, Singular Integral Equation, FEM, cohesive models, scalCrack, scale yielding conditions

Characterization of local mechanical behavior of TA6V weld sheet

L. Rabahi, B. Mehdi, B. Alili, N. KHERROUBA, I. Hadji, R. Badji (2018)
Article de conférence

The present work aims to study the local mechanical behavior of TA6V weld sheet. To this purpose, X-ray Diffraction (XRD), optical microscopy and nano-indentation measurements have been employed. The results highlight strong relationship between the hardness (HIT), Young’s modulus (EIT) values and the microstructure of each zone and phase present along the weld joint. The HIT of the molten zone (MZ) is greater than that of the Heat affected zone (HAZ) and the base metal (MB) in the α phase, whereas it shows small values in the HAZ than that of MB in β phase.Voir les détails

Mots clés : TA6V, Nanoindentation, Microhardness, microstructure.


M.BOULKRA, K. BEY, L. Alimi, S. BOUDIAF, A. Azzi (2018)
Article de conférence

This study consists in the mechanical characterization of a composite material used in the fabrication of orthopedic prostheses by ONAAPH (Annaba- Algeria). The studied composite is the result of a combination of a polymethyl methacrylate (PMMA) resin, fiberglass reinforcements and an absorbent of the resin, namely Perlon. The method adopted for obtaining specimens is the same as that used in the manufacture of prostheses. except that the shape of the mold used in our study is rectangular, allowing to obtain composite plates. The three-point bending tests were carried out on a MTS43 universal machine in the Advanced Materials Research Unit (URMA / CRTI, Annaba/Algeria). The identification of the damage mechanisms according to the mechanical loading conditions as well as the degradation of the constitutive elements, will be discussed.Voir les détails

Mots clés : composite, mechanical tests, mechanical behavior, Finite Elements

Minimisation du stress pour les plaques composites par laméthode des éléments finis

H. Aouaichia, A. Guenanou, H.MERABET, K.BELKAID, H.HAZOURLI, W.RICHI (2018)
Article de conférence

Cette étude est basée sur le phénomène deconcentration de contraintes dans une plaque rectangulaireisotrope et composite soumise à un champ de tractionuniforme. Des trous auxiliaires ont été ajoutés pour réduire lesconcentrations de contraintes. La taille optimale etl'emplacement des trous auxiliaires sont déterminés par uneanalyse paramétrique détaillée en tenant compte des effets desdifférents diamètres et largeur entre les centres des trousprincipaux et auxiliaires. L’évolution du facteur deconcentration de contraintes autour de la plaque est étudiéeanalytiquement par les formulations de Howland et Heywoodet numériquement avec la méthode des éléments finis. Lavaleur minimale du stress est constatée à la présence de deuxtrous auxiliaire.Voir les détails

Mots clés : Vibration Minimisation, traction, Plaque composite, Méthode des éléments fini

Determination of the elasto-viscoplastic parameters for a thermoplastic polymer by instrumented indentation

A. Mokhtari, N. TALA IGHIL (2018)
Article de conférence

The indentation test is a simple, fast and reliable tool that allows the determination of the materials mechanical properties from experimental load-penetration curves using the inverse computation methods. Through this approach and using the Berkovich and spherical indenters, the creep and elasto-plastic properties of the polymers were estimated. Simulations of the elasto-viscoplastic behaviour of the studied polymers under nanoindentation tests were performed. A finite element analysis was carried out to simulate the mechanical behaviour of polymers which can be defined by the Young's modulus E and the parameters (K and n) that describe the materials hardening for large deformations. The obtained functions from the numerical simulations were validated by nanoindentation and compression tests for the studied polymers.Voir les détails

Mots clés : thermoplastic polymers, inverse analysis, nanoindentation test, simulation


A.DELIOU, B.BOUCHOUICHA, I.Atoui, B.Oudjani (2018)
Article de conférence

Vibration monitoring can be an effective method of achieving results, and sometimes at lower costs. This last point, which represents the economic aspect of surveillance, is not negligible for an industrialist. The use of the vibrations involves a phase of analysis of the vibratory signal collected on the machine to be monitored. In our experimental study at the level of the URMA laboratory, we made several tests, namely, without and with defects in the bearings and with a bearing geometric defect at different rotational speeds. The results obtained will allow us to develop a database of the different defects. This will accompany to recognize the exact type of defect and consequently the cause of this damage.Voir les détails

Mots clés : vibration signal, bearing Fault diagnosis, Bearing Fault

Structural Proprieties of CdxZn1-xS Thin Films Deposed by Chemical Bath Deposition

R. Zellagui, H. Dehdouh, F. Boufelgha, T. Sahraoui, M. Adnane (2018)
Article de conférence

The Group II-IV semiconductors are widely used in solar cells based on thin films, among these semiconductors the ternary CdZnS. In this work, we have deposited the CdxZn1-xS thin films on glass substrates by using chemical bath deposition. The synthesized CdZnS thin films were deposited by the chemical bath (CBD). The optical properties and chemical composition of the CdZnS thin films are investigated by EDX and spectrophotometer. The transmittance is 80% in the visible region from 300 nm to 800 nm. The transmittance and the shape change with the concentration of zinc in the solution and from its transmission spectrum, the value of gap energy is between 2.4 eV, the chemical analysis with EDX gives information on the presence of Cd, Zn and S elements and studies stoichiometric. This result favors the application of its films in the solar cells.Voir les détails

Mots clés : CdZnS; Group II-IV semiconductor; chemical bath; transmittance stoichiometry.

FEM simulation of Surface Acoustic wave (saw) device for sensing applications

F. Bettine, F. Laidoudi, F. Medjili, H. Nezzari, H. Merabti, M. MESSAOUDI, A. Derouiche (2017)
Article de conférence

The massive demand by industry to different kind of gas sensors or radiofrequency devices, leads to the need to high sensitivity, high electromechanical coupling electroacoustic devices using novel materials and adequate configurations. This paper aims to the modeling of surface acoustic wave (SAW) based Si/3C-SiC/AlN delay line using finite element approach. The modal analysis allow the extraction of phase velocities, reflectivity and electromechanical coupling factor for different h/λ values, that are of interest before manufacturing process of electroacoustic devices. By optimizing these parameters, high performance and high quality, SAW devices could be fabricated and used in telecommunication or in integrated sensing systems.Voir les détails

Mots clés : AlN, 3C-SiC, Surface acoustic wave, FEM. Sensors, Piezoelectric