Catégorie A

Permanent URI for this collectionhttps://dspacee.univ-temouchent.edu.dz/handle/123456789/605

Browse

Now showing 1 - 20 of 20

A description of internal erosion by suffusion and induced settlements on cohesionless granular matter
(Acta Geotech. 10, 735–748 (2015), 2015-05-29) Sibille, Luc; Marot, Didier; Sail, Yacine
Cohesionless granular matter subjected to internal flow can incur an internal erosion by suffusion characterized by a migration of its finest constituting particles. A series of suffusion tests is performed on assemblies of gap-graded glass beads using a large oedo-permeameter device. Two successive processes of erosion can be observed during the tests. First, a suffusion process is characterized by a progressive and diffuse migration of fine particles over a long time period. The second process, induced by the first one, is characterized by a strong migration over a short time period (blowout of fine particles) and produces rapidly large settlement of specimen. Time series of hydraulic conductivity, longitudinal profile of specimen density, eroded mass and axial deformation are analyzed. The initial content of fine particles and the history of hydraulic loading appear as key parameters in the suffusion development. To characterize the suffusion development, erosion rate is investigated according to the power expended by the seepage flow, and a new law of erosion by suffusion is proposed.
Internal erosion in granular media: direct numerical simulations and energy interpretation
(Wiley on line library, 2014-09-03) Sibille, Luc; Lominé, Franck; Poullain, Philippe; Sail, Yacine; Marot, Didier
Internal erosion in soils is characterized by a first step of detachment of solid particles from the granular skeleton under the action of water seepage; then the detached particles are transported with the water flow. For some erosion processes, such as suffusion, transported particles may finally be redeposited within the interstitial space of the soil itself acting as a filter. This paper focuses on the analysis and the description of the two first steps of particle detachment and transport in the cases of erosion by suffusion and piping erosion. The analysis is mainly based on direct numerical simulations performed with a fully coupled discrete element–lattice Boltzmann method. Inter-particle interactions occurring in the solid granular phase are described with the discrete element method, whereas dynamics of the water flow is solved with the lattice Boltzmann method. Simulation results show that internal erosion of the solid phase can be described either from the hydraulic shear stress or from the power expended by the water seepage. The latter description based on the flow power is finally compared with experimental results from laboratory tests. Copyright © 2014 John Wiley & Sons, Ltd.
Numerical Simulations of an Oscillating Flow Past an Elliptic Cylinder
(Journal of Offshore Mechanics and Arctic Engineering, 2016-02) Daoud, Sid Ahmed; Nehari, Driss; Aichouni, Mohamed; Nehari, Taieb
This paper presents a numerical investigation of a two-dimensional (2D) oscillatory flow around a cylinder of different elliptic ratios, in order to study the effect of the elliptic form of the cylinder on the vorticity field and the hydrodynamic forces that act on it. The elliptic ratio ε was varied from 1 to 0.1, where the small axis is parallel to the flow direction, simulating cases ranging from a circular cylinder to the case of a cylinder with a profiled elliptic section. The investigations presented here are for Reynolds number Re = 100 and Keulegan number KC = 5. The numerical visualization of the flow for different elliptic ratios shows five different modes of vortex shedding (symmetric and asymmetric pairing of attached vortices, single-pair, double-pair, and chaotic), which depend on the range of the elliptic ratio. The results show that the longitudinal force increases with the reduction of the elliptic ratio. The transverse force appears from the elliptic ratio ε and increases with the reduction of this ratio in the range of ε ⁠, then decreases for ε ⁠. On the other hand, concerning the Morison coefficients the results show that the drag coefficient is sensitive to the swirling layout while the coefficient of inertia does not seem to be much affected by the geometry of the cylinder.
Elastic modulus measurements of vertically aligned multi walled carbon nanotubes carpets by using the nanoindentation technique
(Mechanics Research Communications Volume 85, October 2017, Pages 16-20, 2017) Belhenini, Soufyane; Labbaye-Leborgne, Thibault; Boulmer, Chantal; Kovacevic, Eva; Tougui, Abdellah; Dosseul, Franck
Electrical, thermal and mechanical properties of Vertically Aligned Multi Walled Carbon NanoTubes (VA-MWCNT) make them an ideal candidate to replace some of conventional materials in micro and nano-electronic components. Integrating this material in micro components requires a good knowledge of their properties. As the electrical and thermal properties, the MWCNT mechanical properties are difficult to assess. Several techniques have been developed to estimate the CNT Young's modulus and the obtained results cover a large range of scale. In this study, we propose an indirect technique for MWCNT carpet Young's modulus measurements by using the nanoindentation technique. Nanoindentation tests are performed on a metallic film deposited on MWCNT. The measured equivalent reduced modulus takes into account the elastic properties of the metallic thin film and those of the MWCNT substrate. Bec et al. model, introduced in 2006, is used to separate elastic properties, and thus determine the MWCNT reduced Young’s modulus which is estimated between 329 and 352 GPa. Knowing the indenter mechanical properties, we estimate the Young’s modulus in the 461 to507 GPa range.
Analysis of the plastic zone under mixed mode fracture in bonded composite repair of aircraft structures
(Aerospace Science and Technology Volume 69, October 2017, Pages 404-411, 2017-10) OUDAD, Wahid; BELHADRI, Djamal Eddine; FEKIRINI, Hamida; KHODJA, Malika
Material fracture by opening (mode I) is not the only failure criteria responsible for fracture propagation. Many industrial examples show the presence of mode II and mixed mode I + II. In the present work, numerical analyses of the three-dimensional and non-linear finite element method are used to estimate the performance of the bonded composite repair of metallic aircraft structures with a pre-existent damage by analyzing the plastic zone size ahead of repaired cracks under mixed mode loading, to assess the effect of the composite repair system on the plastic zone. The Von Mises stress is used to predict yielding of materials under this loading condition. The extension of the plastic zone, which takes place at the tip of a crack, strictly depends on many variables, such as the yield stress of the material, the loading conditions, the crack size and the thickness of the cracked component. The obtained results have demonstrated that the plastic zone ahead of the crack is significantly reduced by the presence of composite patch materials. Furthermore, parametric analysis has been carried out to evaluate the effect of lay-up and material system variation on the J integral.
A TRNSYS model of a direct contact membrane distillation (DCMD) system coupled to a flat plate solar collector (FPC)
(Journal Europeen des Systemes Automatises. Volume 1 – n° 1/2017, 2017) REMLAOUI, Ahmed; NEHARI, Driss; ELMERIAH, Abderrahmane; LAISSAOUI, Mohammed
A promising water desalination system based on direct contact membrane distillation (DCMD) powered by flat plate solar collector (FPC) is proposed in the present study. The carried out system is modelized and simulated by using the commercial code TRNSYS. Doing this was possible by including a novel component able to simulate the physical behavior of the DCMD. The simulation of the solar distillation system has been done during the 21st june along a daylight of 10 hours under the meteorological conditions of Ain Témouchent city (Algeria). The results showed that the present model has a good agreement with the experimental data of the literature. The present desalination system allows to get a daily distillate production around 42.86 l/d and the specific daily distillate production rate is 10.85 kg for each m2 of FPC. Furthermore, concerning the performance parameters, it was found that the solar fractions ranged from 0 to1 and the collector efficiencies was assessed 74%.
Materials Research Express Inclusive Publishing Trusted Science PAPER Modelling and analysis of the stress distribution in a multi-thin film system Pt/USG/Si
(Materials Research Express 5 046405, no. 4, 2018-04-11) Yao, W Z; Roqueta, F; Craveur, J C; Belhenini, Sofiane; Gardes, P; Tougui, A
Residual stress analysis is commonly achieved through curvature measurement with the help of Stoney's formula. However, this conventional approach is inadequate for multi-layer thin film systems, which are widely used in today's microelectronics. Also, for the thin film case, the residual stress is composed of thermal stress and intrinsic stress. Measuring the wafer curvature at room temperature provides a value for the average stresses in the layer, the two components cannot be distinguished by the existing methodologies of curvature measurement. To alleviate these problems, a modified curvature method combining finite element (FE) modelling is proposed to study the stress distribution in a Pt/USG/Si structure. A 2D FE model is firstly built in order to calculate the thermal stress in the multilayer structure, the obtained thermal stresses in respective films are verified by an analytical model. Then, we calculate the warpage of the multilayer structure by considering the intrinsic stress in the respective films. The residual stresses in the films are determined by minimizing the difference between the simulated warpage and that of experimental measurement. The proposed approach can be used to calculate not only the average residual stress but also thermal and intrinsic stress components in the USG and Platinum films. The obtained residual and intrinsic stresses from a numerical model are compared with the values of other studies. There is no limitation for the application of our methodologies regarding the number of the layers in the stack.
Using Artificial Neural Networks Approach to Estimate Compressive Strength for Rubberized Concrete
(PERIODICA POLYTECHNICA CIVIL ENGINEERING, 2018-03-27) Rahali, Bachir; Sidi Mohammed, Aissa Mamoune; Trouzine, Habib
Artificial neural network (ANN) is a soft computing technique that has been used to predict with accuracy compressive strength known for its high variability of values. ANN is used to develop a model that can predict compressive strength of rubberized concrete where natural aggregate such as fine and coarse aggregate are replaced by crumb rubber and tire chips. The main idea in this study is to build a model using ANN with three parameters that are: water/cement ratio, Superplasticizer, granular squeleton. Furthermore, the data used in the model has been taken from various literatures and are arranged in a format of three input parameters: water/cement ratio, superplasticizer, granular squeleton that gathers fine aggregates, coarse aggregates, crumb rubber, tire chips and output parameter which is compressive strength. The performance of the model has been judged by using correlation coefficient, mean square error, mean absolute error and adopted as the comparative measures against the experimental results obtained from literature. The results indicate that artificial neural network has the ability to predict compressive strength of rubberized concrete with an acceptable degree of accuracy using new parameters.
Impact of spatial variability of earthquake ground motion on seismic response of a railway bridge
(Seismic Resistant Structures, 2018•books.google.com-WIT Press, 2018) DERBAL, , RACHID; BENMANSOUR, NASSIMA; DJAFOUR, MUSTAPHA
This paper studies the impact of spatially varying ground motions on the responses of a railway bridge. The evaluation of the seismic hazard for a given site is to estimate the seismic ground motion at the surface. This is the result of the combination of the action of the seismic source, which generates seismic waves, the propagation of these waves between the source and the site, and the local conditions of the site. Firstly, the seismic ground motions are modelled by assuming the base rock motions of the same intensity and modelling them with a filtered Tajimi-Kanai power spectral density function and a spatial ground motion coherency loss function. Then, the power spectral density function of ground motion on surface is derived by considering the site amplification effect based on the one-dimensional seismic wave propagation theory. A comparison between the bridge responses to uniform ground motion, to spatial ground motions with and without considering local site effects is established. Discussions on the seismic ground motion spatial variability and local site conditions effects on structural responses of railway bridge are made.
Techno-economic analysis of a stand-alone solar desalination plant at variable load conditions
(Applied Thermal Engineering Volume 133, 25 March 2018, Pages 659-670, 2018-03-25) Laissaoui, Mohammed; Palenzuela, Patricia; Sharaf Eldean, Mohamed A; Nehari, Driss; Alarcón-Padilla, Diego-César
The operation of large-scale reverse osmosis units in combination with different solar power plants, both, Concentrating Solar Power (CSP) and Photovoltaics (PV) has been evaluated under variable load conditions. In the case of the Reverse Osmosis (RO) unit, configurations with and without an energy recovery device have been considered. In the case of the CSP plant, a thermal storage system with several capacities (8–14 h) covers the periods with low solar radiation and no storage has been taken into account for the PV plant due to the prohibitively high cost of batteries at large scale. Two scenarios and different strategies within each scenario have been proposed to adapt the operation of the RO unit at partial load in order to assure a stable operation. In the first scenario, the RO unit is represented as a whole unit with variable performance according to the power availability. In the second scenario, the RO unit is composed of 10 sub-units that are switched on/off depending on the power availability. The analysis has been done for a specific location in Algeria and the dynamic performance of the RO unit has been presented for each scenario, together with an economic analysis.
Mechanical Analysis of Low and High Chromium Steels Used in Hot Strip Work Rolls
(Solid State Phenomena (Volume 279), 2018-08-17) Benkhenafou, Fethi; Fernández Pariente, Ines; Belzunce, F Javier; Ziadi, Abdelkader; Quan Shi,Ming
Abstract: Microstructure, hardness and fracture toughness of low and high chromium high speed steel used in hot strip mills and subjected to conventional heat treatment have been examined. The influence of tempering temperatures on the mechanical properties of these products, determined using tensile and fracture toughness tests, was studied in this research work. The developed microstructures have been characterized by XRD, optical microscopy and SEM examinations. Macrohardness and microhardness of the specimens have been evaluated by Vickers indentation technique. The fracture toughness of these products was investigated using the rupture weight on 3 points bending specimens. The plane strain fracture toughness KIc and the fracture strength were measured for each alloy. The shell is high harness high speed steels, and the core is nodular cast iron. It was found that most fracture occurred in the eutectic carbides formed by the high content alloy element, such as Mo,V,Cr, but that for the alloys with a reduced volume fraction of eutectic carbides, a small amount of crack propagation occurred in the austenitic dendrites. Access through your institution
THERMOMECHANICAL ANALYSIS OF THE RESISTANCE SPOT-WELDING PROCESS
(Computational Thermal Sciences: An International Journal, Volume 10, Issue 5, 2018, pp. 449-455, 2018) Lebbal, Habib; Boukhris, Lahouari; Berrekia, Habib; Ziadi, Abdelkader
Resistance spot welding (RSW) is the process of joining two or more metal sheets by fusion at discrete spots at the sheet interface. Resistance to current flow through the metal sheets generates heat. Temperature rises at the sheet interface until the plastic point of the metal is reached, the metal begins to fuse, and a nugget is formed. Current is then switched off and the nugget is allowed to cool down slowly to solidify under pressure. In this article, an axisymmetric contact finite element analysis model of RSW was developed using commercial finite element code, namely ANSYS. A two-dimensional axisymmetric model was used to simulate the thermoelectromechanical coupling of the process to determine temperature distribution and different residual stresses in the contact electrode/sheet and sheet/sheet during the RSW process.
The buckling of piezoelectric plates on pasternak elastic foundation using higher-order shear deformation plate theories
(Smart Structures and Systems Volume 21 Issue 1 /, 2018-01-25) Ellali, Mokhtar; Bouazza, Mokhtar; Bourada, Fouad
In this article, an exact analytical solution for mechanical buckling analysis of magnetoelectroelastic plate resting on pasternak foundation is investigated based on the third-order shear deformation plate theory. The in-plane electric and magnetic fields can be ignored for plates. According to Maxwell equation and magnetoelectric boundary condition, the variation of electric and magnetic potentials along the thickness direction of the plate is determined. The von Karman model is exploited to capture the effect of nonlinearity. Navier's approach has been used to solve the governing equations for all edges simply supported boundary conditions. Numerical results reveal the effects of (i) lateral load, (ii) electric load, (iii) magnetic load and (iv) higher order shear deformation theory on the critical buckling load have been investigated. These results must be the analysis of intelligent structures constructed from magnetoelectroelastic materials.
Nearby Carrier Detection Based on Low Cost RTL-SDR Front End
(Wireless Personal Communications volume 108, pages2341–2358 (2019), 2019-05-10) Yagoub, Reda; Benaissa, Mohamed; Benadda, Belkacem
Recent advances associated with wireless technology are presenting fast development for new wireless telecommunications generations. Development that creates a need for operators and individuals to use hybrid equipment combining the different generation protocol stacks to handle availability and quality of services. Software Defined Radio SDR technology offers new paradigm, allowing single device to handle several digital telecommunications schemes simultaneously. In this article, we are using low cost RTL-SDR front-end receiver to simplify traditional complex hardware and proprietary equipment systems for carrier detection. Our developed solution use the RTL-SDR dongle to detect and monitor nearby carriers activities.
Numerical Investigation of Charging and Discharging Processes of a Shell and Tube Nano-Enhanced Latent Thermal Storage Unit
(J. Thermal Sci. Eng. Appl.Volume 12, Issue 2, 2020-02-28) Nedjem, Khaoula; Teggar, Mohamed; Ismail, Kamal Adbel Radi; Nehari, Driss
Phase change materials (PCMs) generally suffer from low thermal conductivity which limits their application in thermal systems. The effective thermal conductivity may be improved by including fins, metallic powders, fine wires, and nanoparticles. The objective of this study is to investigate the thermal performance of graphene nanoplatelets (GNPs) dispersed in small quantities in 1-tetradecanol (C14H30O) PCM. This nano-enhanced PCM (NPCM) is placed in the annular space of a shell and tube in a solar thermal storage unit. The numerical simulations have been carried out using a numerical model based on the enthalpy-porosity and the control volume methods. The numerical model has been successfully validated by comparison with experimental data available in the literature. The numerical results showed that the higher the GNPs concentration, the lower the stored energy. The higher the GNPs concentration the shorter the discharging time. But, during the charging process, though the reduction in the melting time by 9.5% for GNPs concentration increase from 0 to 1 wt%, the melting time increased in contrast by 10.5% for GNPs content increasing from 1 to 3 wt%. For the GNPs concentration of 3 wt%, the heat transfer rate enhancement was limited by an undesirable increase in viscosity which led to weak natural convection and hence a longer charging time. Thus, the GNPs concentration of 1 wt% showed better thermal performance than that of 3 wt% concentration. These results may guide the improvement of solar thermal storage by dispersing GNPs in PCM.
Effects of Ceramic Waste, Marble Dust, and Cement in Pavement Sub-base Layer
(Geotech Geol Eng 38, 3331–3340, 2020-01-31) Deboucha, Sadek; Aissa Mamoune, Sidi mohammed; Sail, Yacine; Ziani, Hocine
In this work, the effects of ceramic waste (CW), marble dust (MD), and cement on the performance of road sub-base layer characteristics were investigated. Industries routinely produce CW and MD, and the disposal of these types of waste is a major environmental problem in Algeria and worldwide. Thus, the recycling of these waste materials requires the development of long-term solutions. The goal of the current work is to estimate the effects of CW, MD, and ordinary Portland cement (OPC) on the soil of the sub-base layer improving its engineering properties, such as dry density and bearing capacity as measured by the California Bearing Ration (CBR). We planned different admixtures of soil containing 5, 10, and 15% CW, and 2, 3, 4, and 5% MD, and 1.5, and 2% OPC by dry weight. The attainment of sub-base materials was investigated with soil–CW only, soil–MD only, soil–OPC only and soil–CW–OPC. The results showed that the CBR values of sub-base materials increase with the addition of recycled wastes and OPC. The CBR values of mixtures with OPC only and OPC with CW were greater than that of CW and MD only. This work offers the possibility of improving the sub-base layer by the addition of CW, MD, and OPC to obtain greater economic and environmental sustainability through better resource utilization.
Probabilistic analysis of consolidation problems using subset simulation
(Computers and Geotechnics Volume 124, August 2020, 103612, 2020-04-29) Houmadi, Youcef; Yazid, Mohammed; Benmoussa, Cherif; Cherifi, Wafa Nor El Houda; Rahal, Driss Djaouad
In geotechnical structures, the failure probability (Pf) is usually calculated using the Monte Carlo simulation. This method is very time-consuming, particularly when dealing with small failure probabilities. To overcome this problem and as an alternative to MCS, the Subset simulation approach was applied to study the coupled two-dimensional consolidation. This method aims at performing a probabilistic analysis of the consolidation coupled with a heterogeneous soil with spatially varying Young's modulus (E). The probabilistic numerical results have shown that the probability of exceeding an admissible vertical displacement calculated by Subset simulation is very close to that calculated by MCS, but with a very substantial reduction in the number of simulations. In this study, the random field has been discretized into a finite number of random variables using the Karhunen-Loeve expansion. A parametric study to investigate the effect of the soil variability on Pf was presented and discussed. The effect of autocorrelation horizontal and vertical distances Lx and Ly of E on Pf has shown that increasing Lx and Ly increases Pf for both isotropic and anisotropic soils. In addition, this study has shown that Pf is more sensitive to Ly than Lx. Finally, the increase in COV(E) increases Pf.
Prediction of corrosion potential using the generalized artificial neural networks method
(Canadian Journal of Civil Engineering • Vol. 49 • No. 6 • pp. 1040 - 1048, 2021-10-22) Chérifi, Wafa Nor El Houda; Houmadi, Youcef; Aissa Mamoune, Sidi Mohammed
Reinforcement corrosion is one of the main phenomena determining the life of a structure. It can be tracked using methods based on several indicators of the probability of corrosion. These measures can be more or less lengthy and can require very specific equipment. In recent years, several non-destructive tests have been developed that are relatively fast and less costly based on the measurement of corrosion potential. In this study, a statistical analysis is performed, using a multiple linear regression, to test the reliability of the data obtained by experimental measurement of the corrosion potential. Artificial neural networks (ANN) are then used to develop a model to predict the corrosion potential of reinforcement in a concrete or mortar. The results indicate that the artificial neural network can predict corrosion potential with an acceptable degree of accuracy.
On the relevance of incorporating bar slip, bar buckling and low-cycle fatigue effects in seismic fragility assessment of RC bridge piers
(2022-02-18) Bouazza, H; Djelil, M; Matallah, M
The paper reports the results of a numerical investigation on the relevance of including bar slip, bar buckling and low-cycle fatigue in seismic fragility assessment of RC bridge piers. The numerical study is completed on a series of well-confined circular RC bridge column with different configurations where the main variables included are the longitudinal reinforcement ratio, the axial load ratio, the spiral reinforcement ratio and the aspect ratio. Moreover, calculations are performed in several options, namely: (i) Model considering perfect bond (ii) Model considering perfect bond + buckling + fatigue (iii) Model incorporating bar slip only (iv) Model incorporating bar slip + buckling and (v) Model incorporating bar slip + buckling + fatigue. The significance of each individual or combined effect is assessed through comparison of the results from two calculation options. The response of the RC bridge is firstly evaluated through cyclic and monotonic analyses giving indication whether its inherent individual or combined effects should be explicitly considered or if it may be neglected in the probabilistic risk assessment analyses. By considering the main conclusions of the preliminary sensitivity study, the fragility curves are the developed using the Performance-Based Earthquake Engineering (PBEE) methodology. The sensitivity of results to the modelling strategy are discussed in terms of (i) the inelastic seismic demands under strong ground motions using the incremental dynamic analysis (IDA) and (ii) the relative vulnerability developed using probabilistic demand models (PSDM) extracted from the results of the IDA analyses. Based on these studies recommendations are made for the development of reliable and efficient modelling strategy when evaluating the performance of RC bridge piers for use in PBEE.
No AccessMultiphysics analysis of tramway geotechnical infrastructure: numerical modelling
(2023-08-21) Yalaoui, Nadia; Trouzine, Habib; Meghachou, Mourad; Abbès, Boussad; Aissa Mamoune, Sidi Mohammed
Under realistic field conditions, geotechnical infrastructures are usually influenced by complex interactions of mechanical behaviour under the action of an internal water flow. This mechanism could be the main origin of damage to embankments. This study develops a new hydro-mechanical (HM) approach based on Darcy's law model and Biot's poroelastic concept to investigate the behaviour of soil with and without geotextile under realistic conditions. The problem's numerical solution is carried out using a finite-element method. The proposed two-dimensional model was implemented in Comsol Multiphysics Software. Under coupled HM behaviour, the stress in porous materials causes a volumetric change in strain, which causes fluid diffusion. Consequently, pore pressure dissipates through the pores. To discuss the advantages of coupled HM modelling and evaluate the geotextile performance, volumetric strain, pore-water pressure, storage and displacement are compared for a mechanical, hydraulic and HM model. These analyses were undertaken in connection with a tramway embankment project in a marshy area in Sidi Bel Abbes. The simulation results show better results for geotextile and embankment in HM coupled modelling.

Browse

Recent Submissions