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Behavioural Modelling of Corundum under the Effect of Porosity Rate

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Modeling and Numerical Simulation of Material Science 2013年第3期3卷 33-36页

作者： Seif-Eddine Bendaoudi Mokhtar Bounazef el-abbes adda bedia Laboratory LM & H Djillali Liabes University of Sidi Bel-Abbes 89 Algeria

Corundum, which is a form of Alumina, is used to manufacture various components and mechanical, electrical and electronics parts. Known for its relatively high hardness, its other characteristics depend on the porosity rate that varies depending on the manufacturing process. One of the characteristics to consider is the tensile stress value changes in a standard test to failure as a function of applied force and porosity rate. In this study, for a better understanding of the effect of the two parameters, we used the statistical method of design of experiments that makes it possible to establish a mathematical model of the response, by which explains the effect of the two parameters in isolation from each other, then their effect simultaneously. Consequently, we can explain the mechanical behaviour of the porous corundum, with curves and graphs, and optimize the final result.

关键词： Corundum Behavioural Modelling Porosity Rate Design of Experiments Method

Assessment of Cement-Lime as Stabilizer on Mud Bricks

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Journal of Materials Science and Chemical Engineering 2024年第7期12卷 1-13页

作者： Chrisdel Chancelice Ndjeumi Djonga Paul Nestor Djomou George elambo Nkeng Fatoumata adda Souaibou Soulemane Anong Department of Environmental Sciences ENSPM University of Maroua Maroua Cameroon Department of Leather and Textile Engineering ENSPM University of Maroua Maroua Cameroon Department of Civil Environmental and Architectural Engineering University of Padova Padova Italy Laboratory of Analysis of CIMENCAM Garoua Cameroon

The aim of this study was to evaluate the compressive strength of clay bricks and their stability to water absorption by inserting stabilizers such as lime and cement of 0%, 4%, 6%, 8%, 10%, 12% to 14%. Spectrometric analysis was used to characterize the various stabilizers and the clay used, and tests of resistance and water absorption were also carried out. The clay was found to be an aluminosilicate (15.55% to 17.17% Al2O3 and 42.12% to 44.15% SiO2). The lime contains 90.84% CaO and the cement has 17.80% SiO2, 3.46% Al2O3, 2.43% Fe2O3 and 58.47% CaO in the combined form of tricalcium silicate, dicalcium silicate, tricalcium aluminate and ferro-tetra calcium aluminate. The results showed that the insertion of locally available stabilizers (lime and cement) improved the strength of the material by almost 80% when the lime was increased from 0% to 14% for 14 days. For compressed cement, a 65% increase in strength was observed under the same conditions. Strength increases with drying time, with a 52% increase in strength at 28 days compared to 14 days. Furthermore, compressed cement bricks have a more compact structure, absorbing very little water (32%). In view of all these results, cement appears to be the best stabilizer, and compression improves compressive strength and reduces water absorption.

关键词： Cement-Stabilized Earth Lime-Stabilized Earth Compressed Earth Brick Compressive Strength Water Absorption Test

Static Analysis of Functionally Graded Sandwich Plates Using an Efficient and Simple Refined Theory

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Chinese Journal of Aeronautics 2011年第4期24卷 432-433页

作者： Hadj Henni ABDelAZIZ Hassen Ait ATMANE Ismail MECHAB Lakhdar BOUMIA Abdelouahed TOUNSI adda bedia el ABBAS Laboratoire des Matériaux et Hydrologie Université de Sidi Bel Abbes Département de Génie Civil Université Ibn Khaldoun Département de Génie Civil Faculté de Génie Civil et d'Architecture Univesité de Chlef Département de Physique Université de Sidi Bel Abbes

In this paper, a new displacement based high-order shear deformation theory is introduced for the static response of functionally graded sandwich plate. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, has strong similarity with classical plate theory in many aspects, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. Two common types of functionally graded sandwich plates, namely, the sandwich with fimctionally graded facesheet and homogeneous core and the sandwich with homogeneous facesheet and functionally graded core, are considered. Governing equations are derived from the principle of virtual displacements. The closed-form solution of a simply supported rectangular plate subjected to sinu- soidal loading has been obtained by using the Navier method. The validity of the present theory is investigated by comparing some of the present results with those of the classical, the first-order and the other higher-order theories. It can be concluded that the proposed theory is accurate and simple in solving the static bending behavior of functionally graded sandwich plates.

关键词： functionally graded materials sandwich plates refined plate theory bending Navier solution

A two variable refined plate theory for the bending analysis of functionally graded plates

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Acta Mechanica Sinica 2010年第6期26卷 941-949页

作者： Ismail Mechab Hassen Ait Atmane Abdlouahed Tounsi Hichem Abdesselem Belhadj EI Abbas adda bedia Laboratoire des Materiaux et Hydrologie Universite de Sidi Bel AbbesBP 89 Cite Ben M'hidi22000 Sidi Bel AbbesAlgerie Departement de genie civil Faculte des Sciences de l'IngenieurUniversite Hassiba Benbouali de ChlefChlefAlgerie

Bending analysis of functionally graded plates using the two variable refined plate theory is presented in this *** number of unknown functions involved is reduced to merely four,as against five in other shear deformation theories. The variationally consistent theory presented here has, in many respects,strong similarity to the classical plate theory. It does not require shear correction factors,and gives rise to such transverse shear stress variation that the transverse shear stresses vary parabolically across the thickness and satisfy shear stress free surface *** properties of the plate are assumed to be graded in the thickness direction with their distributions following a simple power-law in terms of the volume fractions of the *** equations are derived from the principle of virtual displacements, and a closed-form solution is found for a simply supported rectangular plate subjected to sinusoidal loading by using the Navier *** results obtained by the present theory are compared with available solutions,from which it can be concluded that the proposed theory is accurate and simple in analyzing the static bending behavior of functionally graded plates.

关键词： FG plates Shear deformation theory Refined plate theory Higher-order theory Navier solution

Free vibration of functionally graded sandwich plates using four-variable refined plate theory

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Applied Mathematics and Mechanics(English Edition) 2011年第7期32卷 925-942页

作者： L.HADJI H.A.ATMANE A.TOUNSI I.MECHAB E.A.adda bedia Laboratoire des Matériaux et Hydrologie Université de Sidi Bel AbbesSidi Bel Abbes 22000Algérie Département de Génie Civil Université Ibn KhaldounTiaret 14000Algérie Département de Génie Civil Faculté des Sciences de l'IngénieurUnivesité Hassiba Benbouali de ChlefChlef 02000Algérie

This paper uses the four-variable refined plate theory （RPT） for the free vibration analysis of functionally graded material （FGM） sandwich rectangular plates. Unlike other theories, there are only four unknown functions involved, as compared to five in other shear deformation theories. The theory presented is variationally consistent and strongly similar to the classical plate theory in many aspects. It does not require the shear correction factor, and gives rise to the transverse shear stress variation so that the transverse shear stresses vary parabolically across the thickness to satisfy free surface conditions for the shear stress. Two common types of FGM sandwich plates are considered, namely, the sandwich with the FGM facesheet and the homogeneous core and the sandwich with the homogeneous facesheet and the FGM core. The equation of motion for the FGM sandwich plates is obtained based on Hamilton＇s principle. The closed form solutions are obtained by using the Navier technique. The fundamental frequencies are found by solving the eigenvalue problems. The validity of the theory is shown by comparing the present results with those of the classical, the first-order, and the other higher-order theories. The proposed theory is accurate and simple in solving the free vibration behavior of the FGM sandwich plates.

关键词： functionally graded material (FGM) free vibration sandwich plate refinedplate theory (RPT) Navier solution

ANALYTICAL ANALYSIS OF INTERFACIAL STRESSES IN FRP-RC HYBRID BEAMS WITH TIME-DEPENDENT DEFORMATIONS OF RC BEAM

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Acta Mechanica Solida Sinica 2011年第6期24卷 519-526页

作者： Bouazza Fahsi Kouider Halim Benrahou Baghdad Krour Abdeloauhed Tounsi Samir Benyoucef1 E Abbas adda bedia Laboratoire des Matériaux et Hydrologie Université de Sidi Bel Abbes BP 89 Cité Ben M'hidi 22000 SidiBel Abbes Algéri Universitaire Mustapha Stambouli Mascara Département de Génie Civil Algérie Laboratoire des Matériaux et Hydrologie Université de Sidi Bel Abbes BP 89 Cité Ben M’hidi 22000 SidiBel Abbes Algérie

In this paper, the effect of time-dependent deformations （such as shrinkage and creep） on the interracial stresses between an RC beam and FRP plate is presented. For this end, a closed-form solution for such stresses in externally FRP plated RC beams including creep and shrinkage effects is presented. The developed model is formulated to predict the interfacial stresses at time ＇t＇, in which the RC beams have been already subjected to creep and shrinkage effects. The adherend shear deformations have been included in the present theoretical analysis by assuming a parabolic shear stress through the thickness of the RC beam and the FRP panel. Contrary to some existing studies, the assumption that both RC beam and FRP panel have the same curvature is not used in the present investigation. This research is helpful for the understanding on mechanical behavior of the interface and design of the FRP-RC hybrid structures.

关键词： hybrid structure RC beams FRP composites interfacial stresses creep shrinkage

Natural frequencies of composite beams with a variable fiber volume fraction including rotary inertia and shear deformation

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Applied Mathematics and Mechanics(English Edition) 2009年第6期30卷 717-726页

作者： Y. Bedjilili A. Tounsi H. M. Berrabah I. Mechab E. A. adda bedia S. Benaissa Université de Tlemcen Faculté des Sciences de l'ingénieurDépartement de Génie MécaniqueAlgérie Laboratoire des Matériaux et Hydrologie Université de Sidi Bel AbbesAlgérie Laboratoire de Mathématiques Université de Sidi Bel AbbesAlgérie

The present study is concerned with the vibration analysis of symmetric composite beams with a variable fiber volume fraction through thickness. First-order shear deformation and rotary inertia have been included in the analysis. The solution procedure is applicable to arbitrary boundary conditions. Continuous gradation of the fiber volume fraction is modeled in the form of an m-th power polynomial of the coordinate axis in the thickness direction of the beam. By varying the fiber volume fraction within the symmetric composite beam to create a functionally graded material （FGM）, certain vibration characteristics are affected. Results are presented to demonstrate the effects of shear deformation, fiber volume fraction, and boundary conditions on the natural frequencies and mode shapes of composite beams.

关键词： free vibration functionally graded materials first-order shear deformationtheory

Behavioural Modelling of Lips Seal Made with Polytetrafluoroethylene Enriched by Glass Fibers

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Modeling and Numerical Simulation of Material Science 2013年第4期3卷 170-174页

作者： Ali Djeffal Seif Eddine Bendaoudi Mokhtar Bounazef el Abbas adda bedia Materials and Hydrology Laboratory Department of Civil Engineering Djillali Liabes University Sidi Bel Abbes Algeria Materials and Hydrology Laboratory Department of Mechanical Engineering Djillali Liabes University Sidi Bel Abbes Algeria

Polytetrafluoroethylene reinforced with glass fibers is a composite material widely used in industry mainly for the manufacture of seals at the level of the rotary shafts of vehicles and stationary floor machines such as turbines and compressors. However, due to elastic and viscous-plastic properties of this material, it wears quickly under the influence of some external parameters during operation. There are therefore material loss, increased clearance and loss of sealing. This work summarises a series of tests carried out with this material in order to analyse the variation of the friction coefficient due to the roughness of the work piece brought into contact with the PTFE, the linear velocity of contact between them and material yield strength. To do this analysis, we used the method of unconventional design of experiments to model the behaviour of material and consequently make decisions to reduce this wear. The results are shown and deeply analysed in the following text as a polynomial mathematical model, graphs, contours and response surfaces illustrating the holding of this material under the effect of the three parameters mentioned above. The previous PTFE samples enriched with chopped glass fibers are not subjected to axially force this time, contrary to the force applied radially. The advantage of this method is the relative linear velocity at the contact sample-disc and the applied pressure remains constant. Under the action of the weight “P” applied on the sample, it comes into friction with the rotating disc whose roughness changes from experience to another;it is expressed by the values of Ra. Tangential friction force appears at the point of contact and is equilibrated by measured force Fm on the lever. The calculation of the moment relative bench axis caused by 2 forces gives the coefficient of friction. Knowing the values of frictional force Ft by calculation and the weight P, we determine then the friction coefficient.

关键词： Composite Material Friction Wear Glass Fibers Design of Experiments Modelling

Security and performance evaluation of master node protocol based reputation blockchain in the bitcoin network

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Blockchain(Research and Applications) 2022年第1期3卷 49-64页

作者： Muntadher Sallal Gareth Owenson Dawood Salman Mo adda Bournemouth University PooleDorsetBH125BBUK Cyber Espion Ltd. Port SolentHampshirePO64TYUK University of Portsmouth PortsmouthHampshirePO12UPUK University of Kufa KufaNajaf GovernorateIraq

Bitcoin is a digital currency based on a peer-to-peer network to propagate and verify *** is gaining wider adoption than any previous ***,the mechanism of peers randomly choosing logical neighbours without any knowledge about the underlying physical topology can cause a delay overhead in information propagation which makes the system vulnerable to double spend *** at alleviating the propagation delay problem,this paper introduces a proximity-aware extension to the current Bitcoin protocol,named Master Node Based Clustering(MNBC).The ultimate purpose of the proposed protocol,which is based on how clusters are formulated and how nodes can define their membership,is to improve the information propagation delay in the Bitcoin *** the MNBC protocol,physical internet connectivity increases as well as the number of hops between nodes decreases through assigning nodes to be responsible for maintaining clusters based on physical Internet ***,a reputation-based blockchain protocol is integrated with MNBC protocol in order to securely assign a master node for every *** validate our proposed methods through a set of simulation experiments and the findings show how the proposed methods run and their impact in optimising the transaction propagation delay.

关键词： Information propagation delay Network clustering Bitcoin network Reputation blockchain