Papers by abdelmoumen hamidi
Le procédé du rotomoulage réactif est une technologie de fabrication de pièces creuses de taille ... more Le procédé du rotomoulage réactif est une technologie de fabrication de pièces creuses de taille et géométrie très variés. Une compréhension et une modélisation des phénomènes physiques qui interviennent dans les différentes étapes de la fabrication apportent une contribution importante à la maîtrise de ce procédé. Les travaux abordés dans cette thèse se situent dans le cadre d'un programme plus général visant le contrôle et le pilotage du rotomoulage réactif.Tout d'abord, une caractérisation et modélisation de la cinétique du polyuréthane thermodurcissable en mode dynamique est réalisé suivie par des mesures rhéologiques afin d'établir des lois rhéocinétique ainsi que des lois du comportement viscoélastiques du système réactionnel. Ces lois de comportement sont établies conformément aux conditions réelles de la mise en œuvre du matériau.Ensuite, nous simulons le procédé du rotomoulage en utilisant un code de calcul basé sur la méthode « Smoothed Particle Hydrodynamics »...
Le procede du rotomoulage reactif est une technologie de fabrication de pieces creuses de taille ... more Le procede du rotomoulage reactif est une technologie de fabrication de pieces creuses de taille et geometrie tres varies. Une comprehension et une modelisation des phenomenes physiques qui interviennent dans les differentes etapes de la fabrication apportent une contribution importante a la maitrise de ce procede. Les travaux abordes dans cette these se situent dans le cadre d'un programme plus general visant le controle et le pilotage du rotomoulage reactif.Tout d'abord, une caracterisation et modelisation de la cinetique du polyurethane thermodurcissable en mode dynamique est realise suivie par des mesures rheologiques afin d'etablir des lois rheocinetique ainsi que des lois du comportement viscoelastiques du systeme reactionnel. Ces lois de comportement sont etablies conformement aux conditions reelles de la mise en œuvre du materiau.Ensuite, nous simulons le procede du rotomoulage en utilisant un code de calcul base sur la methode « Smoothed Particle Hydrodynamics »...
International Journal of Material Forming, Mar 18, 2015
During Reactive Rotational Molding (RRM), it is very important to predict the fluid flow in order... more During Reactive Rotational Molding (RRM), it is very important to predict the fluid flow in order to obtain the piece with homogeneous shape and high quality. This prediction may be possible by simulation the fluid flow during rotational molding. In this study we have used a mixture of isocyanate and polyol as reactive system. The kinetic rheological behaviors of thermoset polyurethane are investigated in anisothermal conditions. Thanks to these, rheokinetik model of polyurethane was identified. Then, to simulate the RRM, we have applied Smoothed Particles Hydrodynamics (SPH) method which is suited method to simulate the fluid flow with free surface such as occurs at RRM. Modelling and simulating reactive system flow depend on different parameters; one of them is the surface tension of reactive fluid. To implement force tension surface, the interface between polymer and air is dynamically tracked by finding the particles on this border. First, the boundary particles are detected by free-surface detection algorithm developed by Barecasco, Terissa and NAA [1, 2] in two and three dimension. Then, analytical and geometrical algorithms have been used for interface reconstructions. The aim of this work is the implementation of surface tension force in the SPH solver applied to RRM. To illustrate that, we used novel and simple geometric algorithm fitting circle and fitting sphere, in two and three dimensional configurations, respectively. The model has been validated using a well-known dam break test case which covered the experimental data.
The Reactive Rotational Molding (RRM) is a manufacturing method for the production of one-piece h... more The Reactive Rotational Molding (RRM) is a manufacturing method for the production of one-piece hollow plastic part where the polymer synthesis and shaping of piece is carried simultaneously using heat and bi-axial rotation. The main drawback of RRM is poor control of the process due to the high number of influent parameters. In these conditions, the optimization of the process is quite complex. During RRM, it is very important to predict the fluid flow in order to be able to obtain a piece with homogeneous shape and with high quality. For this study, we have applied Smoothed Particles Hydrodynamics (SPH) to simulate the polymer flow during this process taking into account surface tension force. To implement force tension surface, the interface between polymer and air is tracked dynamically by seeking the particles constituting this border by algorithm developed by Barecasco, Terissa and NAA[1,2] in two and three dimensional. Then, we use Lagrangian interpolation or fitting circle to reconstruct the interface curve in two dimensions, and we apply the fitting sphere method in three dimensions to reconstruct the boundary surface. By using the basic method of SPH for fluid modeling, and a combination of 2D and 3D free curve or surface detection algorithm with interpolation method, we can simulate polymer flow phenomena during RRM with expected result.
International Journal of Material Forming
This paper concerns the study of sintering phenomenon during rotational molding of polypropylene(... more This paper concerns the study of sintering phenomenon during rotational molding of polypropylene(PP), Polyvinylidenefluoride (PVDF) and Polymethyl methacrylate (PMMA). First, the coalescence (first step of sintering) of two grains has been followed. Bellehumeur’s model has been tested as a model to explain this phenomenon. In order to study the effect of neighbouring grains on coalescence of two grains, a third grain has been put in contact with these two grains. For modelling the phenomenon in this case, Bellehumeur’s model has been modified by a geometric parameter called Farz Factor (FF), being this model validated by experimental test. Concerning densification, two different stages have been observed. In the first stage, before welding of the grains and formation of interphases between them, the grains are not stuck yet. The air trapped between the grains escapes through free ways between grains. This first step of densification is directly related to the coalescence where the d...
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Papers by abdelmoumen hamidi