Browsing by Author "Lecheb, Samir"

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An advanced dynamic repair of edge crack aluminum plate with a composite patch
(Trans Tech Publications Ltd, 2014) Lecheb, Samir; Nour, Abdelkader; Chellil, Ahmed; Mechakra, Hamza; Amarache, A.; Kebir, H
In this work, repaired crack in 2024 T3 aluminium plate with composite patch is presented, the problem is handled in plane stress condition under tensile Mode I crack growth. In the numerical simulation, firstly we determine the displacement, strain and stress, also the first six mode shapes of the plate, secondly we compare the first results with result of a cracked plate, thirdly we repair the crack with composite patch for different materials (Glass, Boron, carbon) and for (2 layers, 4 layers). Finally the comparison of stress, strain, displacement and six first natural frequencies between uncracked, crack initiation and composite patch repair crack. The best offer operating according to the need is selected
Aeroelastic stability analysis of composite rotor blade
(IEEE, 2013) Chellil, Ahmed; Settet, A.T.; Lecheb, Samir; Nour, Abdelkader
Book of Abstract of the 2nd National Conference on Mechanic and Material (NCMM’2023)
(2023) Chellil, A.; Lecheb, Samir; Mechakra, H.; Safi, B.; Daoui, A.
Comportement à la fatigue cyclique d’une aube par les caractéristiques vibratoires
(2012) Lecheb, Samir
Correction : Investigating the efect of process parameters for fused flament fabrication
(Springer, 2023) Boumedine, Asma; Lecheb, Samir; Benfriha, Khaled; Omnes, Pascal
Crack growth diagnostic of ball bearing using vibration analysis
(Sciendo, 2022) Belaid, S.; Lecheb, Samir; Chelil, A.; Mechakra, H.; Safi, Brahim; Kebir, H.
It is known that supported ball bearings have great effects on the vibrations of the gear transmission system, above in all the presence of local faults as well as the crack growths. For this purpose, this paper focuses on shock and vibration crack growth diagnostic of ball bearing using vibration analysis. Our work is devoted first to a study the static behaviour of the ball bearing by determining the stress, strain and displacement, then its dynamic behaviour by determining the first four natural frequencies. Secondly, a dynamic analysis study of the bearing was carried with defects as a function of crack size and location. The obtained results clearly show that the natural frequencies decrease in a non-linear way with the growth of the length of the crack, on the other hand the stress increases with the presence of the singular points of the crack. Finally, this residual decrease in natural frequencies can be used as an indicator of the state of failure, as well as a parameter used for the diagnosis and screening, and to highlight the fatigue life of the bearing
Crack identification in plates-type structures using natural frequencies coupled with success-history based adaptive differential evolution algorithm.
(EBESCO, 2023) Brihmat, Chahira; Amoura, Nasreddine; Lecheb, Samir; Kebir, Hocine; Ait Chikh, Mohamed Abdessamad; Tablit, Bassima
In this study, a new method for identifying and characterizing straight cracks in plate-like structures is presented. The method combines the finite element method (FEM) using the software Abaqus and the success history-based adaptive differential evolution algorithm (SHADE). The objective of the method is to minimize the mean relative error between the measured experimental frequencies of a plate with an unknown crack identity and the numerical frequencies obtained using the Shade-FEM approach. The crack identity is defined by its length, orientation, and centre coordinates. To validate the effectiveness of the proposed approach, two strategies are applied. In the first strategy, the inverse problem is solved using the natural frequencies of a plate with a known crack identity obtained through modal simulation in Abaqus. In the second strategy, the experimental frequencies of a cracked plate are used. The results of the study demonstrate that the proposed approach achieves promising results with just a population size of 25 and 150 iterations. The outcomes show high accuracy, as indicated by a relative error of the objective function below 0.8%. Overall, the study demonstrates the effectiveness of using the Shade-FEM approach for identifying and characterizing straight cracks in plate-like structures, offering potential applications in various engineering and structural integrity fields.
Damage crack growth detection of composite pipeline using NDT
(Université M'Hamed Bougara Boumerdes : Faculté de Technologie : Département Génie Mécanique, 2021) Brihmat, Chahira; Lecheb, Samir; Chellil, A.; Safi, B.; Kebir, H.; Mechakra, H.; Tablit, B.
Damage diagnostic of ball Bearing using vibration analysis
(Université M'Hamed Bougara Boumerdes : Faculté de Technologie, 2021) Belaid, Siham; Lecheb, Samir; Chellil, Ahmed; Djellab, Amira; Mechakra, Hamza; Kebir, Hocine
Maintenance of any machinery is very important in view of downtime of machinery. The bearing sector is one of the examples without which not single rotating machinery work, Our work is devoted first to a study of static behavior by determining the stress, strain and displacement, then dynamic behavior by determining the first four naturals frequencies. Secondly the dynamic analysis of the Bearing with defect as a function of crack size and location. Finally, the analysis of the results obtained in terms of residual parameters, allow us to draw a roadmap for the diagnosis and maintenance of bearings.
Dynamic behavior to fatigue crack initiation of a glass/epoxy laminate
(Trans Tech Publications, 2014) Lecheb, Samir; Nour, Abdelkader; Chellil, Ahmed; Lechani, R.; Kebir, H.
This paper based to study of the dynamic and fatigue behaviors with numerical and experimental parts of a composite material manufactured by stacking two layers of E-glass fiber in different angle orientations (0°/90°) immersed in polyester resin with total thickness 1.39mm. In Finite Element Analysis (FEA) using ABAQUS was used to evaluate the maximal (displacement, strain and stress) and the natural frequencies (mode shapes) of composite behavior under crack initiation condition. In the experimental part the laminate plate specimen with two layers is tested under one types of cyclic load in fully reversible tensile at (R=0), the fast fracture occur phenomenon and the fatigue life are presented, the fatigue testing exerted in INSTRON 8801 machine.
Dynamic modeling of milling and effect of tool path on machining stability
(Springer, 2022) Ikkache, Kamel; Chellil, Ahmed; Lecheb, Samir; Mechakra, Hamza
Regenerative stability theory predicts a set of optimal, stable spindle speeds at integer fractions of the natural frequency of the most flexible mode of the system. Being able to predict these phenomena therefore makes it easier to choose cutting conditions to increase productivity. The three-dimensional study of milling with a spherical tool has been done, and a part of complex shape, it is the continuation of our work previously published. Recently, several theoretical models have been developed for various applications, but there have been very few studies on the particular case of three-axis, complex shape milling. In this paper, it is planned to study the stability of milling operations with a hemispherical tool, using differential equations with delay terms. In this paper, based on the 3D study using a different model, new parameters are introduced in order to compare it with the 2D study of the paper previously published. For a 6061-T6 aluminum alloy part, the model is based on the method of discretization by delay terms of the dynamic equation. Our work has been devoted to have the machining stability lobes in 3D format, along the entire trajectory (discretized in several interpolation segments) of the tool for a flat, inclined (ascending or descending) and complex shaped surface
Dynamic prediction fatigue life of composite wind turbine blade
(Techno Press, 2015) Lecheb, Samir; Nour, Abdelkader; Chellil, Ahmed; Mechakra, Hamza; Ghanem, Hicham; Kebir, Hocine
Effect of nanosilica-doped superplasticizer on the properties of cement mortars
(STEF92 Technology, 2023) Safi, Brahim; Mechakra, Hamza; Saidi, Mohammed; Lecheb, Samir
Recently, nanotechnology has attracted a considerable scientific interest due the potential new uses of non-particles, which can improve the properties of cement mortars or concretes, such as Nanosilica. Nanoparticles, like those of nanosilica, have been shown to have unique physical and chemical properties different from those of conventional cement additions. Nanosilica was used either to replace part of the cements or as an addition to improve the performance of the cement such as accelerating the hydration of the cement phases. This work investigates the effect of nanosilica adding to superplasticizer on fresh and hardened properties of cement mortars. For this, three superplasticizer types of three different firms doped with nanosilica (NS) at 1.5% wt. of superplasticizer (SP) to estimate the effect of nanosilica-based superplasticizer on the properties of cement mortars in the fresh and hardened state. An experimental study was conducted to evaluate the three SP based on NS on fresh and hardened properties. Our results show that nanosilica is compatible with the three superplasticizer, what is remarkable on the mortars in the fresh state, with a good workability which is between (24cm and 28cm) and a total absence of segregation which acts on the mechanical properties of the self-consolidating mortar in (3,7 and 28 days).
Effect of stitch orientation on tensile and flexural bending mechanical properties and damage mechanisms of Glass/Epoxy laminated composites
(2021) Mechakra, Hamza; Lecheb, Samir; Chellil, Ahmed; Safi, Brahim
In this study, the effect of stitch row directions on tensile and flexural bending mechanical properties of composite laminates reinforced by glass-fabric was experimentally investigated. For the fabrication of stitched laminates a polyester thread used to stitch the dry fabric glass in fourth cases (longitudinal stitch 0°, transversal stitch 90°, multi-stitching 0°/90° and 45°/-45° stitch) with 4 mm stitch spacing. The responses of stitched laminates specimens subject to the tests mentioned was compared to the unstitched laminates and discussed. According to our results, the effect of stitching plays of opposite roles on tensile property by decreasing of about 45% and 36% in tensile strength and longitudinal modulus compared to unstitched specimens, respectively. However, an increasing approximately 11.69% to 20.25% in flexural strength found in specimens stitched along 0° and multi-stitching 0°/90°, due to the stitch lines through thickness by arrests temporally of cracks propagation and the delamination progressively propagate between layers.
Etude du comportement dynamique du rotor anti-couple d'un l'hélicoptère
(2008) Lecheb, Samir
Ce Travail propose une étude théorique et numérique sur le comportement dynamique en flexion de rotor anti-couple de l'hélicoptère. On détermine les caractéristiques des éléments de rotor. Il s'agit d'évaluer les expressions des énergies cinétiques et de déformation ainsi que le travail virtuel correspondant aux éléments de base : disque, arbre, palier et balourd. Deux méthodes théoriques sont utilisées : la méthode de Rayleigh-Ritz, lorsqu' il s'agit de mettre en évidence les phénomènes, et la méthode des éléments finis quand il s'agit de prévoir le comportement dynamique des machines réelles. On déduit les équations du mouvement à partir des équations de Lagrange. La simulation numérique nous permet d'observer et mettre en évidence: l'analyse modale, l'analyse nodale et les réponses à diverses excitations
Experimental and numerical investigation of impact behavior in honeycomb sandwich composites
(SAGE, 2024) Djellab, Amira; Chellil, Ahmed; Lecheb, Samir; Safi, Brahim; Mechakra, Hamza; Houari, Amin; Kebir, Hocine; Madani, Kouider
This paper presents an experimental and numerical study on the low-energy impact fatigue and bending behavior of sandwich panels reinforced with composite laminate glass and carbon fabric facesheets, supported by a honeycomb core made of Nomex. The crushing behavior of honeycomb sandwich specimens subjected to the impact test was compared and discussed. Our results indicate that the carbon composite facesheets have a significant effect on the impact, resulting in an increase in impact resistance and a 157.14% increase in crack depth in the elastic region compared to glass facesheets reinforcement. This increase serves as an indicator of the laminate's ability to resist damage initiation and impact fracture mechanisms. Also, an increasing in flexural strength about 45.72% was observed in carbon facesheets honeycomb specimens compared to glass facesheets reinforcement. Microscopic illustration of the damaged honeycomb sandwich specimens was conducted to evaluate the interfacial characteristics and describe the damage mechanics of the composite facesheets and core adhesion under the impact test. The numerical approach proves to be efficient in terms of accuracy and simplicity compared to existing methods for predicting the damage mechanisms of honeycomb sandwich structures. It was noted that results of numerical study show best agreements with experiment results and the model can be used to predict the low-energy impact fatigue.
Failure Prediction of Laminated Composites: Simulation of the Nonlinear Behavior and Progressive Damage
(Korean Fiber Society, 2023) Bensalem, Abdelhafid; Daoui, Abdelhakim; Cheriet, Abderrahmane; Lecheb, Samir; Chellil, Ahmed; Kebir, Hocine; Aissani, Linda
The Hashin’s criteria are useful in composite structural applications because of their simple concept and their theoretical results are relatively close to that got in the experimental parts. In the present study, in the present study, the failure of the composite laminates under static loading have been developed predicted using Hashin’s Criterion. Nonhomogeneous stresses within a structure may induce a complicated failure scenario whereby one ply at a point can initiate failure and can affect also other plies at the same point or the same ply in different neighboring points. With neglecting the possibility of interlaminar failure, only in-plane loads are considered in this state. The results showed that the failure analysis was proposed to simulate the nonlinear laminate behavior and progressive damage of selected laminates under to their ultimate strength. In our approach, the finite element analysis is performed using MATLAB software to study the effect of tensile and compressive loading on the failure of epoxy resin laminate AS4/3501-6.
Handbook non destructif test NDT
(Université M’Hamad Bougara de Boumerdes : Faculté de Technologie Département de Génie Mécanique, 2022) Lecheb, Samir
Identification of vibratory characteristics to the damage of a composite plate
(2018) Grabi, Massinissa; Chellil, A.; Lecheb, Samir; Mechakra, H.; Nour, A.; Andrianarison, O.
tThe objective of this work is to study the damage behavior of composite structures by examining the influence on fatigue resistance. The finite element model of the plate will allow to analyze the vibratory behavior, to identify the stress, to study the influence of the dynamic loads on the natural frequencies of the plate in bending and torsion and will show the influence of the orientation of the Composite fiber macros on the rigidity of the plate and finally calculate the stability of the plate. The various damage mechanisms associated with these materials will also be presented with particular attention to delamination and cracking. This work will then focus on different technologies to improve the mechanical properties of these composite materials.
Impact Behavior Analysis of Luffa/Epoxy Composites Under Low-Velocity Loading
(Springer Nature, 2024) Grabi, Massinissa; Chellil, Ahmed; Lecheb, Samir; Grabi, Hocine; Nour, Abdelkader
Luffa cylindrical (LC) has an exceptionally multipartite architecture, a hierarchical and light structure, and a low density. Such a structure is potentially suitable to replace conventional porous-type composites for low-energy absorption and material reinforcement applications. This paper presents an experimental study of the impact behavior of four different luffa/epoxy composites, named (A), (B), (C), and (D) subjected to low-velocity impact (LVI) at energies ranging from barely visible impact damage (BVID) to perforation (5,15, and 20J). Acoustic emission (AE), scanning electron microscopy (SEM), and digital image correlation (DIC) were introduced to the indentation test to offer additional information on damage mechanisms and on strain and displacement fields since the LVI test has a short duration and real-time damage monitoring is not always achievable. The results showed that the values of the peak force of laminates (A), (B), and (D) are relatively lower compared to laminates (C). In the case of perforation impact energy (20J), the Coefficients of Restitution (CoR) of composites (A), (B), and (D) are equal to 0, which indicates that the nature of the impact is completely plastic, except for composite (C) had a value of 0.11, and a lower degree of damage at all impact energies. Composites (C) exhibit the highest impact resistance, followed by composites (A), while composites (D) display the highest energy absorption, followed by composites (B). Multivariable statistical analysis of the AE signals identified four classes of damage: matrix cracking, fiber-matrix debonding, delamination, and fiber breakage. The damage modes found by AE are well presented and proven by SEM analysis. The luffa fiber-reinforced composite has better impact properties than other natural fiber-reinforced composites.