Papers by mostapha tarfaoui
Journal of Composites Science
One of the biggest problems facing the use of carbon nanotubes in reinforced composites is agglom... more One of the biggest problems facing the use of carbon nanotubes in reinforced composites is agglomeration within the matrix phase. This phenomenon—caused by Van der Waals forces—leads to dispersion problems and weakens the properties of the composites. This research presents a multi-stage homogenization approach used to investigate the influence of the aspect ratio, volume fraction, and agglomeration of the nanofillers on the effective mechanical properties of a polymer biocomposite containing randomly dispersed carbon nanotubes and graphene nanoplatelets. The first stage consisted in evaluating the properties of the reinforced polymers by the CNT/GNP. The second step consisted in combining the reinforced polymers with different natural and synthetic unidirectionally oriented fibers. It was found that agglomeration has a huge influence on the mechanical properties of the composite. The novelty of this work consisted of the consideration of the parameters influencing the elastic prope...
E3S Web of Conferences
The blades of wind turbines placed in cold climate regions are exposed to the risk of icing pheno... more The blades of wind turbines placed in cold climate regions are exposed to the risk of icing phenomena which impact their lifetimes. This paper proposes a numerical model to simulate 50 mm ice thickness localized on the tip side of a horizontal wind turbine blade, and to study its mechanical behavior. The wind turbine blade wasmodeled with the finite element method (FEM)in ABAQUS software taking into account aerodynamic, centrifugal and inertial loads under the conditions of service of the blade.Numerical tests haveevaluated the behavior of different composite materials and compared with each other. Damage mode based on the Hashin criteria was defined. Carbon fibers were considered to be the most rigid material which results in thinner, stiffer and lighter blades.
HAL (Le Centre pour la Communication Scientifique Directe), Apr 11, 2017
Wind Engineering, 2021
In the far north, low temperatures and atmospheric icing are a major danger for the safe operatio... more In the far north, low temperatures and atmospheric icing are a major danger for the safe operation of wind turbines. It can cause several problems in fatigue loads, the balance of the rotor and aerodynamics. With the aim of improving the rigidity of the wind turbine blade, composite materials are currently being used. A numerical work aims to evaluate the effect of ice on composite blades and to determine the most adequate material under icing conditions. Different ice thicknesses are considered in the lower part of the blade. In this paper, modal analysis is performed to obtain the natural frequencies and corresponding mode shapes of the structure. This analysis is elaborated using the finite element method (FEM) computer program through ABAQUS software. The results have laid that the natural frequencies of the blade varied according to the material and thickness of ice and that there is no resonance phenomenon.
Glass-polyester composites have promising application in the maritime domain, especially in the o... more Glass-polyester composites have promising application in the maritime domain, especially in the offshore energy industries due to their low cost, high strength-to-weight and stiffness-to-weight ratios, and corrosion resistance. Tidal turbines propose a new opportunity to use these materials to exploit ocean current flows to generate energy at locations with catastrophic loading. This investigation focuses on the Hygrothermal and mechanical performance evaluation of glass-polyester for renewable marine energy applications. The optimal design and the dynamic behavior of the turbine are studied. The hygrothermal effect and the hydrodynamic and hydrostatic pressures over the loading and the distribution of the stress, the deformation, and damaged zone under are presented.
Materials, 2020
Currently, the emergence of a novel human coronavirus disease, named COVID-19, has become a great... more Currently, the emergence of a novel human coronavirus disease, named COVID-19, has become a great global public health concern causing severe respiratory tract infections in humans. Yet, there is no specific vaccine or treatment for this COVID-19 where anti-disease measures rely on preventing or slowing the transmission of infection from one person to another. In particularly, there is a growing effort to prevent or reduce transmission to frontline healthcare professionals. However, it is becoming an increasingly international concern respecting the shortage in the supply chain of critical single-use personal protective equipment (PPE). To that scope, we aim in the present work to provide a comprehensive overview of the latest 3D printing efforts against COVID-19, including professional additive manufacturing (AM) providers, makers and designers in the 3D printing community. Through this review paper, the response to several questions and inquiries regarding the following issues are...
The International Journal of Advanced Manufacturing Technology, 2021
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
International Journal of Automotive and Mechanical Engineering, 2020
The composite tidal turbine nozzle can be exposed to impact loads during maintenance or installat... more The composite tidal turbine nozzle can be exposed to impact loads during maintenance or installation operations, which may result in invisible damage. Therefore, it is very important to analyse the induced damage in order to conceive hybrid composite nozzles with better resistance to damage. The low-velocity impact behaviour (LVI) of a carbon/glass hybrid composite nozzle has been investigated based on this motivation. The configurations of stacking sequences were constituted of glass and carbon fibers. The results acquired were compared between five various laminated. Indeed, the impact was studied in the leading edge region of the nozzle. The damaged laminates were inspected by the finite element method (FEM) based on Hashin failure criterion using the ABAQUS software. The energy conservation of the nozzle was verified to validate the numerical model. Futhermore, the effect of accidental impact on dynamic response and the damage induced on a hybrid composite nozzle have been inves...
International Journal of Automotive and Mechanical Engineering, 2019
Marine energy is gaining more and more interest in recent years and, in comparison to fossil ener... more Marine energy is gaining more and more interest in recent years and, in comparison to fossil energy, is very attractive due to predictable energy output, renewable and sustainable, the Horizontal Axis Hydrokinetic Turbine (HAHT) is one of the most innovative energy systems that allow transforms the kinetic energy into electricity. This work presents a new series of hydrofoil sections, named here NTSXX20, and was designed to work at different turbine functioning requirement. These hydrofoils have excellent hydrodynamic characteristics at the operating Reynolds number. The design of the turbine has been done utilising XFLR5 code and QBlade which is a Blade-Element Momentum solver with a blade design feature. Tidal current turbine has been able to capture about 50% from TSR range of 5 to 9 with maximum CPower of 51 % at TSR=6,5. The hydrodynamics performance for the CFD cases was presented and was employed to explain the complete response of the turbine.
Advanced Materials Letters, 2018
Several industrial applications have exposed polymer matrix composite materials to a very high st... more Several industrial applications have exposed polymer matrix composite materials to a very high strain rate loading conditions, requiring an ability to understand and predict the material behaviour under these extreme conditions. Many composite aircraft structures such as fuselage, wing skins, engine nacelles and fan blades are situated such that impacts at high strain rates are a realistic threat. To investigate this threat, high velocity impact experiments and subsequent numerical analysis were performed in order to study the compressive loading of composite materials at high strain rates. Specimens are subjected with various orientations from low to high strain rates to determine the compressive material properties. Three fibre orientations such as: ±20°, ±60° and 90° of cubic geometry are tested in in-plane direction. The tests show a strong material sensitivity to dynamic loading and fibre direction. In the second part, the FEA results of the dynamic tests resulting in no damage appeared satisfactory. The FEA gives results which are in coherence with the experimental data. The improved understanding of these phenomena and the development of predictive tools is part of an ongoing effort to improve the long-term integrity of composite structures under dynamic loads.
Composite Structures, 2018
In this investigation, a new experimental technique in which the deformation, damage mode, and th... more In this investigation, a new experimental technique in which the deformation, damage mode, and the temperature are measured simultaneously during a high strain rate on laminated composites materials. The composites consist of unidirectional E-glass fibers reinforced epoxy polymer composites used in industrial applications. The experimental setup consists of a compression Split Hopkinson Pressure Bar (SHPB), a high-speed infrared camera and a high-speed Fastcam rapid camera. Specimens, with cubic like a shape, are impacted at different strain rates ranging from 200 to 2000s-1. During impact test, the specimen surface is controlled and monitored with the infrared camera which provides thermal images in time sequence and with high-speed camera which acquires the damage progressive in specimens. Experimental results show that the damage throughout specimens differs and the temperature change depending on the damage mode and their maximum exceed 219°C.
Composite Structures, 2017
The use of composite materials begin to normalize in various sectors, however, these structures a... more The use of composite materials begin to normalize in various sectors, however, these structures are very susceptible to degradation of their properties and consequently a catastrophic failure. The response of deformable composite subjected to water-entry impact can cause a phenomenon called hydro-elastic effect due to water-flexible laminate interaction. This phenomenon may be large enough to cause the damage in composite panels. This paper employs the finite element method to simulate the behavior of composite wedges under slamming impact with presence of damage. To investigate this situation, the hydro-elastic influence has been analysis as both kinematic effect due to deflection of the composite panel and dynamic effect caused by the interaction between the water and the structure. On the other hand, damage modeling was formulated based on continuum damage mechanics for intra-laminar damage. A user-defined material subroutine VUMAT has been incorporated into explicit Abaqus FE software to enhance the damage simulation, which includes Hashin criteria for degradation of the panel stiffness with failure onset criteria and fracture mechanics. To reinforce the methodology adopted, numerical results are compared with the previous experimental data. A good agreement was observed. Effects of impact velocity and the panels flexibility on the damage have been investigated.
Fracture of Nano and Engineering Materials and Structures
Journal of Composite Materials, 2006
The impact behavior of composite materials has been extensively studied but interest has been cen... more The impact behavior of composite materials has been extensively studied but interest has been centered on flat plates. For underwater applications, thick composite cylinders are employed and several questions must be addressed concerning the influence of accidental impact. The aim of this work is to study the dynamic response of tubular structures. Such structures find many applications but the damage upon impact is not taken into account during their dimensioning. However, at the time of their handling or in service the damage introduced by accidental impact can compromise their capacity to fulfill their function. The cylinders are thick and consist of epoxy matrix and glass fiber reinforcement. After having observed the nature of the damage related to the static and dynamic loading, the scale and size effects on dynamic response and damage are examined. The studies reveal that the dynamic responses show a satisfactory correlation with predictions based on rules of similitude.
Composites Science and Technology, 2008
This study examines the mechanical characteristics of composite structures evolving with the stra... more This study examines the mechanical characteristics of composite structures evolving with the strain rates. The purpose of this work is the use of Split Hopkinson Pressure Bar (SHPB) for the dynamic characterization of the fibre orientation and strain rate effects in particular on the mechanical behaviour, the damage and the strength of a glass/epoxy composite, very much used in the naval domain. It is also a question of understanding the microscopic mechanisms leading to the damage and the failure of material and of quantifying their evolution with the strain rate. The materials examined in the study were all manufactured using the infusion process. E-glass fibres were impregnated with a low viscosity epoxy resin. Samples, of cubic geometry, are tested in the thickness direction for seven fibre orientations, 0°, ±20°, ±30°, ±45°, ±60°, ±70° and 90°.
Composites Part B: Engineering, 2005
This paper presents experimental results obtained from quasi-static and impact indentation tests ... more This paper presents experimental results obtained from quasi-static and impact indentation tests on thick G558 filament wound glass/epoxy tubes intended for underwater applications. Drop weight impact tests have been performed on 55 mm internal diameter 6 mm thick tubes at energies up to 45 J. Ultrasonic inspection was employed first to determine projected damage areas. A large number of samples were then sectioned and polished and the true damage area was revealed by a dye penetrant technique. This has enabled detailed descriptions of damage development to be made. The true damage area is roughly 10 times the projected area. The influence of impact damage on implosion pressure is described. Above a critical impact energy level a significant drop in implosion resistance is noted, which is related to the appearance of intralaminar cracks.
Wind Engineering, 2020
In recent years, several wind turbines have been installed in cold climate sites and are menaced ... more In recent years, several wind turbines have been installed in cold climate sites and are menaced by the icing phenomenon. This article focuses on two parts: the study of the aerodynamic and structural performances of wind turbines subject to atmospheric icing. Firstly, the aerodynamic analysis of NACA 4412 airfoil was obtained using QBlade software for a clean and iced profile. Finite element method (FEM) was employed using ABAQUS software to simulate the structural behavior of a wind turbine blade with 100 mm ice thickness. A comparative study of two composite materials and two blade positions were considered in this section. Hashin criterion was chosen to identify the failure modes and determine the most sensitive areas of the structure. It has been found that the aerodynamic and structural performance of the turbine were degraded when ice accumulated on the leading edge of the blade and changed the shape of its profile.
Polymers
In this work, we investigated the effect of carbon nanotubes addition and agglomeration formation... more In this work, we investigated the effect of carbon nanotubes addition and agglomeration formation on the mechanical and electrical properties of CNT–polymer-based nanocomposites. Six specimens with carbon nanotubes (CNTs) fractions of 0%, 0.5%, 1%, 2%, 4% and 5% were manufactured and characterized by dynamic mechanical analysis (DMA) and four-probe method. The stress–strain curves and electrical conductivity properties were obtained. Scanning electron microscopy (SEM) was used to characterize both agglomeration and porosity formation. By employing micromechanics, through representative volume element (RVE), finite element analysis (FEA) and resistor network model (RNM), the Young’s modulus and electrical conductivity values were calculated. The samples’ elastic moduli showed an increment, reaching the maximum value at a CNTs fraction of 2%, thereafter an adverse effect was caused in the high CNT percentage samples. The final electrical conductivity seemed greatly altered with the ad...
Journal of Composites Science
The structural, thermal, and mechanical properties of unreinforced and reinforced polylactic acid... more The structural, thermal, and mechanical properties of unreinforced and reinforced polylactic acid (PLA) were investigated. The PLA was a biopolymer that was reinforced with four fillers (i.e., graphene oxide (GO) and silver (Ag); vermiculite (VMT) and silver (Ag); and two organically modified vermiculites). The processing technique for the production of the composite materials were carefully planned. The PLA nanocomposites were investigated by examining their morphological aspects, changes in PLA phases and transitions and, most importantly, the effect on certain final properties. X-ray diffraction and differential scanning calorimetry (DSC) analysis indicated that the sample was completely amorphous. Thermogravimetric analysis (TGA) results indicated that the presence of reinforcing particles in the PLA matrix did not affect the thermal degradation of these composites. Furthermore, the local mechanical properties were investigated using the microindentation method to evaluate the e...
Composites show better performance than traditional materials however, they are inclined to damag... more Composites show better performance than traditional materials however, they are inclined to damage formation, delamination, or fracture. So, it is necessary to detect damage or crack formation with in time in these materials to avoid a ny catastrophic incident. Therefore, numerous researchers have been developing in-situ sensors and monitoring systems for composite structures. The objective of this study is to create a micro scale, flexible strain sensor wire for real-time sensing applications. This strain sensor wire was developed by depositing conductive silver (Ag) nanoparticles on the surface of Ny-6 untwisted yarn using electroless plating process to achieve uniform conductive coating over each filament of the Ny-6 polymer. The electro-mechanical behavior of this Ny/Ag sensor wire was verified experimentally and gauge factor was found to be in range of 62-69. This flexible Ny/Ag sensor wire was then integrated with in a composite sample to validate the monitoring of deformation and detection of damage initiation. Experimental procedure was performed where the mechanical behavior of the composite sample was tested in a standard tensometer machine, while the electrical signal of the Ny/Ag sensor wire was recorded. The results showed that the electrical response of the sensor was correlated perfectly with the mechanical behavior of the specimen. This indicated that Ny/Ag strain sensor wire can be used for real-time damage detection and structural health monitoring (SHM) applications.
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Papers by mostapha tarfaoui