239 research outputs found
sj-docx-1-pie-10.1177_09544089231215218 - Supplemental material for Numerical and experimental investigation of a centrifugal compressor: Prospects of polymer additive manufacturing
No full textSupplemental material, sj-docx-1-pie-10.1177_09544089231215218 for Numerical and experimental investigation of a centrifugal compressor: Prospects of polymer additive manufacturing by Nader Zirak, Van-Thang Nguyen, Michael Deligant, Mohammadali Shirinbayan, Amélie Danlos, Grzegorz Żywica, Manuel Henner, Rodrigo Benevides, Farid Bakir and Abbas Tcharkhtchi in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
sj-docx-2-pie-10.1177_09544089231215218 - Supplemental material for Numerical and experimental investigation of a centrifugal compressor: Prospects of polymer additive manufacturing
No full textSupplemental material, sj-docx-2-pie-10.1177_09544089231215218 for Numerical and experimental investigation of a centrifugal compressor: Prospects of polymer additive manufacturing by Nader Zirak, Van-Thang Nguyen, Michael Deligant, Mohammadali Shirinbayan, Amélie Danlos, Grzegorz Żywica, Manuel Henner, Rodrigo Benevides, Farid Bakir and Abbas Tcharkhtchi in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
Thermal transfer simulation regarding the rotational moulding of polyamide 11
No full textSimulation of thermal phenomena in rotational moulding is very important to follow the evolution of the temperature in various zones of this process. It was a question of modelling heat gradients developing in rota-tional moulding part. Thermal model tested take into account the temperature change (thermal transfer mecha-nism) of melting and crystallization pseudo-stages (enthalpy method). Series of tests in polyamide 11 (PA11) were carried out by means of rotational moulding STP LAB, and non-isothermal crystallization kinetics of rota-tional moulding PA11 grade are measured and analysed by DSC technique type TAQ20. A result of non-isothermal crystallization of the studied polyamide was confronted with Ozawa model. In order to test the validity degree of enthalpy method (layer to layer), another approach based on Ozawa model has also been used in the case of cooling pseudo-stage. As results, the rotational moulding of PA11 was successfully carried out. The simulation of the fusion and crystallization stages, by application of Ozawa model coupled with enthalpy method gave a good representation of experimental data
Rotational Moulding of Thermosets: Understanding of a Reactive Forming Process
No full textL'auteur Abbas TCHARKHTCHI faisait parti en 2008 du Laboratoire d’Ingénierie des Matériaux (LIM). Depuis 2010, le LIM a fusionné avec deux autres unités de recherche en un seul laboratoire intitulé PIMM (Procédés et Ingénierie en Mécanique et Matériaux). Il fait parti du groupe de recherche : Procédés et Performance des Polymères et Composites.Physical and chemical transformations of polyurethane thermoset are studied by means of thermal analysis, infrared spectrophotometer and dynamic rheology. Gel point, which limits the material flow, is given as a function of conversion and as a function of time by kinetic law. Glass transition corresponding to a dramatic transformation of the material is also explored and connected to conversion and time. These ex situ characterizations are then exploited in terms of rotational moulding process parameters to improve the understanding and thus the control of the process. Therefore in situ thermal analyses are handled to confirm first results. Final parts thickness distribution is examined as a quantitative parameter of process quality. Finally, as a perspective, ultrasonic response is also studied as a new way to follow material evolution directly in the forming mould
Some New Concepts of Shape Memory Effect of Polymers
No full textIn this study some new concepts regarding certain aspects related to shape memory polymers are presented. A blend of polylactic acid (PLA) (80%) and polybutylene succinate (PBS) (20%) was prepared first by extrusion, then by injection molding to obtain the samples. Tensile, stress-relaxation and recovery tests were performed on these samples at 70 °C. The results indicated that the blend can only regain 24% of its initial shape. It was shown that, this partial shape memory effect could be improved by successive cycles of shape memory tests. After a fourth cycle, the blend is able to regain 82% of its shape. These original results indicated that a polymer without (or with partial) shape memory effect may be transformed into a shape memory polymer without any chemical modification. In this work, we have also shown the relationship between shape memory and property memory effect. Mono and multi-frequency DMA (dynamic mechanical analyzer) tests on virgin and 100% recovered samples of polyurethane (PU) revealed that the polymer at the end of the shape memory tests regains 100% of its initial form without regaining some of its physical properties like glass transition temperature, tensile modulus, heat expansion coefficient and free volume fraction. Shape memory (with and without stress-relaxation) tests were performed on the samples in order to show the role of residual stresses during recovery tests. On the basis of the results we have tried to show the origin of the driving force responsible for shape memory effect
Polymères à Mémoire de Forme: Etude du Polyuréthane et du blend Poly(ε-Caprolactone)/Styrène-Butadiène-Styrène
No full textL’objectif de ce projet est l’étude de l’effet de mémoire de forme du Polyuréthane et du blend Poly(ε-Caprolactone) /Styrène-Butadiène-Styrène. On essaye de caractériser et quantifier cet effet à travers d’un cycle thermomécanique pour deux types de polymères complètement différents.
L’étude réalisée comprends : la caractérisation thermochimique des polymères et essais de traction, relaxation et récupération par chauffage que forment le cycle thermomécanique. On optimise la proportion du blend pour avoir l’effet et le PU est testé à différentes températures pour comprendre son effet sur la récupération.Outgoin
Polymères à Mémoire de Forme: Etude du Polyuréthane et du blend Poly(ε-Caprolactone)/Styrène-Butadiène-Styrène
No full textL’objectif de ce projet est l’étude de l’effet de mémoire de forme du Polyuréthane et du blend Poly(ε-Caprolactone) /Styrène-Butadiène-Styrène. On essaye de caractériser et quantifier cet effet à travers d’un cycle thermomécanique pour deux types de polymères complètement différents.
L’étude réalisée comprends : la caractérisation thermochimique des polymères et essais de traction, relaxation et récupération par chauffage que forment le cycle thermomécanique. On optimise la proportion du blend pour avoir l’effet et le PU est testé à différentes températures pour comprendre son effet sur la récupération.Outgoin
Polymères à Mémoire de Forme: Etude du Polyuréthane et du blend Poly(ε-Caprolactone)/Styrène-Butadiène-Styrène
No full textL’objectif de ce projet est l’étude de l’effet de mémoire de forme du Polyuréthane et du blend Poly(ε-Caprolactone) /Styrène-Butadiène-Styrène. On essaye de caractériser et quantifier cet effet à travers d’un cycle thermomécanique pour deux types de polymères complètement différents.
L’étude réalisée comprends : la caractérisation thermochimique des polymères et essais de traction, relaxation et récupération par chauffage que forment le cycle thermomécanique. On optimise la proportion du blend pour avoir l’effet et le PU est testé à différentes températures pour comprendre son effet sur la récupération.Outgoin
Polylactic acid (PLA) crystallisation study and modeling for rotomolding process optimization
No full textLe rotomoulage est une technique de transformation des polymères thermoplastiques qui souffre encore aujourd'hui d'un certain empirisme. Depuis de nombreuses années, la simulation du procédé de rotomoulage est considérée comme une nécessité à l'introduction de nouveaux matériaux et à l'élargissement de ses domaines applications. Ces travaux s'inscrivent à la suite de nombreuses études visant à développer un logiciel de simulation permettant de prédire le comportement de la matière en condition de mise en œuvre.L'objectif de cette thèse est de s'intéresser plus particulièrement à la simulation de la phase de refroidissement. Pour cela, il est nécessaire de mettre au point un modèle décrivant la cinétique de cristallisation et pouvant tenir compte des contraintes liées aux conditions thermiques extrêmes dans lequel se déroule le procédé (température, présence d'oxygène, temps de cycle long), lesquelles peuvent avoir une influence sur la thermostabilité du polymère. Dans le cadre de cette étude, le choix s'est porté sur le Polylactide (PLA). Le PLA présente une faible stabilité thermique et une cinétique de cristallisation lente, ce qui facilite l'observation de ces deux phénomènes. Dans un premier temps, la thermodégradation du PLA a été étudiée et un modèle visant à décrire son évolution dans des conditions proches de celles du procédé, a été mis en place. Puis, une étude de cristallisation considérant l'influence de la masse moléculaire et du polymorphisme du PLA, a été réalisée afin de modéliser sa cinétique. Enfin, un couplage des deux modèles a été envisagé dans l'optique de les intégrer à une simulation globale des transferts thermiques impliqués dans le procédé de rotomoulage.Rotational molding is a thermoplastic polymer processing technology which has been, for many years, suffering from a kind of empiricism.The simulation of rotational molding is believed to be the key to introduce new materials and more diversity in its applications. This work follows several studies aimed to develop a simulation software which would predict the material behavior in processing conditions.Consequently, this thesis will focus specifically on the simulation of the cooling phase. This type of simulation requires kinetic crystallization modeling, acknowledging the influence that the extreme thermal conditions of the rotomolding process can have on the thermal stability of the material. In this study we chose to work with Polylactic acid (PLA), a material suffering poor thermal stability and presenting with slow kinetic crystallization, making it suitable to observe these phenomenona. First, the thermal degradation of PLA has been studied and a model describing its behavior, under similar conditions to processing, has been proposed. Then, a crystallization study including the influence of the molecular weight, as well as the polymorphism of PLA, has been completed and the kinetic crystallization modeling has been performed. Finally, the integration of both models in a global simulation of the thermal transfers describing the rotomolding process has been investigated
3D Printing as a Multidisciplinary Field
No full textInternational audience3D printing, also known as additive manufacturing, has emerged as a versatile and multidisciplinary field with widespread implications. It intersects with various domains including engineering, medicine, art, and materials science. This technology's ability to convert digital designs into physical objects layer by layer has revolutionized industries such as aerospace, automotive, and consumer goods by facilitating rapid prototyping and customization. Moreover, this technology has spurred advances in materials science through precise material manipulation, leading to innovative materials with enhanced properties. Challenges such as material limitations, process refinement, and legal concerns persist, but 3D printing's interdisciplinary nature continues to drive transformative advancements across various sectors. Therefore, multiphysics optimization plays a pivotal role in advancing the realm of 3D printing by addressing the intricate balance between conflicting design objectives. In this innovative manufacturing process, where material properties, structural integrity, print speed, and cost-effectiveness often collide, multiphysics optimization emerges as a critical tool. It allows designers and engineers to systematically explore a vast design space, enabling the identification of optimal solutions that consider not only a singular objective but also a spectrum of interrelated goals. By optimizing factors such as layer thickness, infill density, and printing speed, practitioners can achieve outcomes that strike harmonious equilibrium between strength, quality, and efficiency. Ultimately, the integration of multiphysics optimization into 3D printing catalyzes the creation of functional and intricately designed objects, revolutionizing industries ranging from aerospace to healthcare and redefining the boundaries of additive manufacturing possibilities
- …
