Browsing by Author "BELGACEM MAMEN"
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Item Assessment of the effect of the materials composition on the bending response of FG plates lying on two models of elastic foundations in thermo-hygro-mechanical environments(2023-09-20) BELGACEM MAMENThis study fulfils a thermo-hygro-mechanical analysis of the bending behavior of FG plates resting on different elastic foundation models. A quasi-3D high-order shear deformation theory with five unknowns is used herein to perform this analysis. The impact of shear deformation and stretching effect are included in the formulation of the used approach. The result of the change in material characteristics and the volumetric fraction of components on the bending response of FG plates in a thermo-hygro-mechanical environment is analyzed and discussed. The principle of virtual displacements is used to obtain the equilibrium equations, and the Navier-type solution is applied to solve the resulting equations. The results show that the increase in thermal load and moisture concentration causes a rapid deflection increase. Furthermore, the Winkler parameter influences the shear stresses more than the deflections.Item boundary conditions; distribution models; FG sandwich plates; harmonic thermal load; thermodynamic bending; Winkler/Pasternak/Kerr foundation(2024-02-18) BELGACEM MAMENThis paper presents an analytical formulation to investigate functionally graded porous beams’ nonlinear thermal buckling performance under various boundary conditions. The current model incorporates innovative cinematic techniques with the focus on the stretching effect and the iteration techniques. The material properties of the porous FG beams are temperature-dependent and vary according to a simple powerlaw distribution. The validity of the present theory’ results is confirmed by comparing them with those obtained by other researchers. The findings demonstrate that the critical buckling temperature in TD and TID ranges from 1.03 to 1.27% for a uniform distribution and 1 to 1.47% for linear and non-linear distributions. Conversely, for regular porosity variation, the critical buckling temperatures fluctuate between 0.99 and 1.74%, and between 0.99 and 1.59% for porosity variation. Furthermore, the influence of boundary conditions becomes more pronounced when the nonlinear temperature difference is highItem Buckling behaviors of FG porous sandwich plates with metallic foam cores resting on elastic foundation(2022-12-30) BELGACEM MAMENThe main objective of this paper is to study the effect of porosity on the buckling behavior of thick functionally graded sandwich plate resting on various boundary conditions under different in-plane loads. The formulation is made for a newly developed sandwich plate using a functional gradient material based on a modified power law function of symmetric and asymmetric configuration. Four different porosity distribution are considered and varied in accordance with material propriety variation in the thickness direction of the face sheets of sandwich plate, metal foam also is considered in this study on the second model of sandwich which containing metal foam core and FGM face sheets. New quasi-3D high shear deformation theory is used here for this investigate; the present kinematic model introduces only six variables with stretching effect by adopting a new indeterminate integral variable in the displacement field. The stability equations are obtained by Hamilton’s principle then solved by generalized solution. The effect of Pasternak and Winkler elastic foundations also including here. the present model validated with those found in the open literature, then the impact of different parameters: porosities index, foam cells distribution, boundary conditions, elastic foundation, power law index, ratio aspect, side-to-thickness ratio and different in-plane axial loads on the variation of the buckling behavior are demonstratedItem Combined Effect of Thickness Stretching and Temperature‑Dependent Material Properties on Dynamic Behavior of Imperfect FG Beams Using Three Variable Quasi‑3D Model(2022-09-11) BELGACEM MAMENPurpose The multi-step sequential infiltration technique or sintering process usually produces porosities in functionally graded structures. It is confirmed that the porosity significantly influences the static responses of FGM beams, but its influence on their thermodynamic response is still worth studying. Methods To highlight this influence, the dynamic behavior of simply-supported porous FG beams with effective temperaturedependent material properties is examined by using a novel integral three variable quasi-3D high-order shear deformation theory for the first time. Notably, different thermal gradients varying along the thickness are considered. The governing differential equations of motion have been established based on Hamilton’s principle and solved by employing the Naviertype closedform solution. Results The present theoretical results are validated with the existing literature, and excellent agreement is identified between the results. Besides, material temperature dependence, power-law index, porosity parameter, temperature rising, and slenderness ratio effects are discussed. Results show that dynamic behavior using temperature-dependent and independent material properties would produce different natural frequencies. With the rise of porosity, the natural frequency decreases significantly at high temperatures. Conclusions The beam with a higher slenderness ratio is more sensitive to the stretching effect. Finally, to improve the thermodynamic behavior of such structures, ceramic constituents with a lower thermal expansion coefficient would be recommended.Item Combined influence of porosity and elastic foundation parameters on the bending behavior of advanced sandwich structures(2022-12-06) BELGACEM MAMENElastic bending of imperfect functionally graded sandwich plates (FGSPs) laying on the Winkler-Pasternak foundation and subjected to sinusoidal loads is analyzed. The analyses have been established using the quasi-3D sinusoidal shear deformation model. In this theory, the number of unknowns is condensed to only five unknowns using integral-undefined terms without requiring any correction shear factor. Moreover, the current constituent material properties of the middle layer is considered homogeneous and isotropic. But those of the top and bottom face sheets of the graded porous sandwich plate (FGSP) are supposed to vary regularly and continuously in the direction of thickness according to the trigonometric volume fraction’s model. The corresponding equilibrium equations of FGSPs with simply supported edges are derived via the static version of the Hamilton’s principle. The differential equations of the system are resolved via Navier’s method for various schemes of FGSPs. The current study examine the impact of the material index, porosity, side-to-thickness ratio, aspect ratio, and the WinklerPasternak foundation on the displacements, axial and shear stresses of the sandwich structure.Item Critical thermal shock temperature prediction of alumina using improved hybrid models based on artificial neural networks and Shannon entropy(2022-04-26) BELGACEM MAMENThis study investigates the potential of a simple and Hybrid artificial neural network (ANN) to predict dense alumina's critical thermal shock temperature (ΔTc). The predictive models have been constructed using two ANNS models (M1, M2). In the first model (M1), elaboration, physical and mechanical parameters have been exploited to build three ANNs, namely generalized linear regression (M1-GLRNN), extreme learning machine (M1-ELM), and radial basis function (M1-RBFNN). The second model (M2) has been built by the three models mentioned above incorporated by the Shannon Entropy (SE) method. To compare the performance of all the developed models, coefficient of correlation (R), root mean square error (RMSE), mean absolute percentage error (MAPE), and Nash-Sutcliffe efficiency coefficient (NSE) have been considered. It is found that M2-RBFNN model with (RMSE = 4.3526, MAPE= 0.3406, NSE = 0.9921, and R= 0.9960) had superiority to the M1-RBFNN model (RMSE = 4.7030, MAPE= 0.3003, NSE = 0.9908, and R = 0.9954). More importantly, the contribution of the present work is that prediction of ΔTc has been performed through the developed hybrid model (M2-RBFNN), which reduces the number of inputs from six to only four inputs and offers high accuracy for all the studied variables.Item EXPERIMENTAL INVESTIGATION AND NON-LOCAL MODELLING OF THE THERMOMECHANICAL BEHAVIOUR OF REFRACTORY CONCRETE(2021-08-16) BELGACEM MAMENThis paper describes an experimental characterisation and a non-local finite element analysis on the influence of the testing temperature on the mechanical properties and cracking propagation in refractory cement bricks. Therefore, isothermal four-point bending and uniaxial compression tests have been carried out at different testing temperatures (25, 500, 800, and 1000 °C) to determine the stress-strain response for each independent testing temperature. Based on this response, material constants are identified using the inverse estimation method. Then, they are introduced in a non-local finite element model using CAST3M software. The experimental results indicate that with an increase in the testing temperature, the thermomechanical behaviour of the refractory concrete shows a critical temperature of 800 °C, for which the compression and tensile strengths are the largest. Their values are respectively around 28 and 9 MPa. The present numerical simulation results indicate two types of crack propagation; continuous crack failures when the temperature varies between 25 and 800 °C and multi-identified cracks producing a localised damage zone at 1000 °C. Notably, the sample tested at 1000 °C requires a deflection of 0.2 mm to achieve 0.3 (30 % damaged). In contrast, the damage variable achieves 1.0 (100 % in damage) for the sample tested at 25 °C with the same imposed displacement (0.2 mm). Finally, the enhanced non-local damage model produces a realistic simulation of the experimental failure mechanisms, proving the validity of the implementation methodItem Experimental investigation on the mechanical behavior of concrete reinforced with Alfa fibers(2022-04-01) BELGACEM MAMENCurrently, the reinforcement of ordinary concrete with synthetic fibers poses ecological problems because the manufacturing process of these products is very polluting. Plant fiber composites are a new challenge for environmental protection. The present article aims to investigate the mechanical behavior of concrete reinforced with natural fibers, called alfa fibers. Compression and three-point bending tests have been performed on cubic and prismatic samples, respectively. Different fiber lengths (2.5, 5, and 8 cm) and content (0.6, 1.2, and 1.8 % by volume) of alfa fibers have been used to examine their influence on the mechanical behavior of the fiberreinforced concrete. The obtained results show that for a volume content of 1.2 % of plant fibers of 5 cm length, the tensile strength of the reinforced concrete increases up to 54.41 % compared to the ordinary concrete (BT). However, for a content of 1.8 % of fibers with 8 cm length, both the compressive and tensile strength of the reinforced concrete decrease slightly. At this level, an excess of both fiber content and their length produces the formation of voids within concrete. Moreover, such an excess made the hydration reaction slower. It is worth noticing that the orientation of fibers also plays a significant role in the nucleation and propagation of microcracks. The fibers arranged both horizontally and obliquely are more resistant to microcracking than those oriented in the loading direction.Item EXPERIMENTAL VERIFICATION OF THE NEW MODELS APPLIED TO GLASS FIBRE REINFORCED CONCRETE (GFRC) CONFINED WITH GLASS FIBRE REINFORCED POLYMER (GFRP) COMPOSITES(2022-07-21) BELGACEM MAMENExternal confinement by the GFRP composites offers an actual process for retrofitting glass fibre reinforced concrete columns (GFRC) subject to static or seismic loads. This paper presents an experimental investigation and analytical modelling of the axial compression of confined circular concrete columns of different strengths (8.5, 16, and 25 MPa). Furthermore, the columns contain different percentages of glass fibres (0.3 to 1.2 %), and their confinement is given by GFRP composites of various thicknesses (0.8 to 2.4 mm). The uniaxial compression test on these specimens reveals that the glass fibre percentage and the thickness of the GFRP play a vital role in improving the load-deformation behaviour and crack propagation. Whatever the concrete strength, the ultimate axial strain and stress predicted using the suggested confinement model almost agrees with the available experimental resultsItem IMPACT OF THE SHEAR AND THICKNESS STRETCHING EFFECTS ON THE FREE VIBRATIONS OF ADVANCED COMPOSITE PLATES(2023-02-28) BELGACEM MAMENQuasi-3D high-order shear deformation theories (HSDT) are often more effective for investigating advanced composite thick plates than two-dimensional (2D) theories. The present study examines the specific dimensionality effect of quasi-3D HSDT theories through-thickness stretching on the free vibration behavior of thin-thick rectangular plates. For this purpose, a 3D displacement field defined by only five unknowns is proposed. Besides, it contains a stretching component that contributes to the whole behavior of the plate. The results of the 2D model are compared to the results of the quasi-3D model. In addition, several factors, such as the aspect ratio, geometrical ratio, and material index, illustrate the influence of dimensionality. Young’s modulus and densities should be graded in the direction of thickness. The motion equations are deduced based on Hamilton’s principle. According to the boundary condition type, Navier’s solution method is used for solving the obtained equations. The results show that the inclusion of the stretching component would increase the dynamic response of the thick advanced composite plates. Moreover, the influence of dimensionality is less significant for pure ceramic platesItem Investigation on machining of a Ti–6Al–4V alloy using FEM simulation and experimental analysis(2022-12-07) BELGACEM MAMENTitanium alloys have been attracting from the more industries, especially, industry aerospace due to their very important high strength to weight ratio. Furthermore, they were classified as difficult to machine materials due to low tool life in machining processes. In this study, a FE model has been developed to simulate the turning stage of Ti–6Al–4V alloy. A 3D model with thermo-mechanical coupling has been proposed to study the influence of cutting parameters and also lubrication on the performance of cutting tools. The constants of the Johnson–Cook constitutive model of Ti–6Al–4V alloy were identified using inverse analysis based on the process parameters of the orthogonal cutting. The predictive FE model has been validated based on an orthogonal cutting test. The investigations indicated that this approach estimates the resultant cutting forces with low prediction errors. Indeed, the predicted forces showed good agreement with the experimental data, with minimum and maximum error magnitudes of 2.8 and 8.7% for cutting force, and 1.3 and 6.8% for feed force, respectively.Item New Anchorage Technique for GFRP Flexural Strengthening of Concrete Beams Using Bolts-End Anchoring System(2023) BELGACEM MAMENThe concept of external glass FRP composite confinement is a current process for strengthening concrete beams subjected to static loads. End anchorage glass FRP composites of 80 mm width and 90–130 mm length with different thicknesses (2.4 and 4.8 mm) have been fixed at the bottom of beams with bolts of various diameters (6 and 10 mm). For this purpose, the behavior of beams strengthened with bolt-end anchoring glass fiber polymer composites (BEGFPC) has been analyzed. It is concluded that the load capacity of the BEGFPC beams is improved by increasing the end-anchorage glass FRP composite thickness (about 98–188%). In addition, the BEGFPC system with bolts of 6 mm diameter has significantly improved the flexibility of beams. In contrast, the 10 mm bolts in diameter give a high ultimate load, whatever their quantity. Therefore, combining bolts with diameters of 6 and 10 mm would be the best solution for increasing the ultimate load and ductility of the retrofitted beams. Depending on the number and bolts’ arrangement, there is also an enhancement in the crack patterns by changing from intermediate flexural failure to shear failure in beamsItem Seismic Fragility of a Single Pillar-Column Under Near and Far Fault Soil Motion with Consideration of Soil-Pile Interaction(2022-10-31) BELGACEM MAMENhe soil-structure interaction is a significant challenge faced by civil engineers due to the complexity potential in terms of seismic fragility evaluation. This paper presents a seismic fragility estimation of a single pier considering seismic ground motion types. Furthermore, sand type, pile diameter, pier height, and mass variation were considered to estimate their effect on the seismic fragility of the concrete pier. Incremental dynamic analysis was performed using a beam on a nonlinear Winkler foundation model. The analysis model condition compared near- and far-ground motion effects. Dynamic analysis and fragility assessment of the single-pier structure showed that low mass center produced less vulnerability of the concrete pier in the two cases of the sand type under near- and far-ground motions. The near and far earthquake simulations at complete failure probability had a difference of less than 5% when 0.65sItem SOLID MECHANICS QUASI-3D ANALYTIC MODEL FOR FREE VIBRATION ANALYSIS OF SIMPLY SUPPORTED FUNCTIONALLY GRADED PLATES (SS-FGP)(2023-03-09) BELGACEM MAMENThis paper uses a quasi-3D shear deformation theory accounting for integral terms and including the stretching effect to study the free vibration of FG plates with simply supported edges. A new function shape is used to show the variation of tangential stresses through the z-direction of the plate. Poisson’s ratio is supposed to be constant, but Young’s modulus and densities are assumed to be graded in the thickness direction according to the power law function. The present plate theory satisfies the zero tension on the upper and lower surfaces of the FG plate without using shear correction factors. The equations of motion are obtained via Hamilton’s principle and solved using Navier’s solution type. The present natural frequencies correspond with the ones in many publications; the outcomes of geometrical ratio, side to thickness ratio, and the material index on the natural frequencies of SS-FGP are investigated.Item Static buckling analysis of bi-directional functionally graded sandwich (BFGSW) beams with two different boundary conditions(2022-08-09) BELGACEM MAMENThis paper presents the mechanical buckling of bi-directional functionally graded sandwich beams (BFGSW) with various boundary conditions employing a quasi-3D beam theory, including an integral term in the displacement field, which reduces the number of unknowns and governing equations. The beams are composed of three layers. The core is made from two constituents and varies across the thickness; however, the covering layers of the beams are made of bidirectional functionally graded material (BFGSW) and vary smoothly along the beam length and thickness directions. The power gradation model is considered to estimate the variation of material properties. The used formulation reflects the transverse shear effect and uses only three variables without including the correction factor used in the first shear deformation theory (FSDT) proposed by Timoshenko. The principle of virtual forces is used to obtain stability equations. Moreover, the impacts of the control of the power-law index, layer thickness ratio, length-to-depth ratio, and boundary conditions on buckling response are demonstrated. Our contribution in the present work is applying an analytical solution to investigate the stability behavior of bidirectional FG sandwich beams under various boundaryItem Thickness stretching and nonlinear hygro-thermo-mechanical loading effects on bending behavior of FG beams(2022-12-06) BELGACEM MAMENIn this paper, the nonlinear vibration behavior of the spiral stiffened multilayer functionally graded (SSMFG) cylindrical shells exposed to the thermal environment and a uniformly distributed harmonic loading using a semi-analytical method is investigated. The cylindrical shell is surrounded by a nonlinear viscoelastic foundation consisting of a two-parameter Winkler-Pasternak foundation augmented by a Kelvin-Voigt viscoelastic model with a nonlinear cubic stiffness. The distribution of temperature and material constitutive of the stiffeners are continuously changed through the thickness direction. The cylindrical shell has three layers consisting of metal, FGM, and ceramic. The interior layer of the cylindrical shell is rich in metal, while the exterior layer is rich in ceramic, and the FG material is located between two layers. The nonlinear vibration problem utilizing the smeared stiffeners technique, the von Kármán equations, and the Galerkin method has been solved. The multiple scales method is utilized to examine the nonlinear vibration behavior of SSMFG cylindrical shells. The considered resonant case is 1:3:9 internal resonance and subharmonic resonance of order 1/3. The influences of different material and geometrical parameters on the vibration behavior of SSMFG cylindrical shells are examined. The results show that the angles of stiffeners, temperature, and elastic foundation parameters have a strong effect on the vibration behaviors of the SSMFG cylindrical shells.