The present work can be regarded as a first step toward an integrated modelling of mould filling ... more The present work can be regarded as a first step toward an integrated modelling of mould filling during injection moulding process of polymer matrix composites and the resulting material behaviour under service loading conditions. More precisely, the emphasis of the present research is laid on the development of a mechanical model which takes into account the processing-induced microstructure and is capable to predict the mechanical response of the material. In the Part I, a set of experiments which captures the mechanical behaviour of an injection moulded short fibre reinforced under different strain histories is described. Three mechanical testing are conducted: Dynamic Mechanical Analysis (DMA), uniaxial tension and simple shear. Tests show that the material exhibits complex responses mainly due to non-linearity, anisotropy, time/rate-dependence, hysteresis and permanent strain. Moreover, the relaxed state of the material is characterized by the existence of a so-called anisotropic equilibrium hysteresis independently of the prescribed strain rate.
Canadian Journal of Chemical Engineering, Dec 1, 2002
... Billon, N., H. Kappel, S. Crozet, F. Bay, J.-F. Agassant and JM Haudin, “Relations Anisotropi... more ... Billon, N., H. Kappel, S. Crozet, F. Bay, J.-F. Agassant and JM Haudin, “Relations Anisotropie – Propriétés Mécaniques de Tubes ... in Tubular Film and Melt Spinning of Rheologically Characterized High Density, Low Density and Linear Low Density Polyethylene”, J. Non-Newt. ...
Poly(ethylene 2,5-furandicarboxylate), PEF and poly(ethylene terephthalate), PET, are two polyest... more Poly(ethylene 2,5-furandicarboxylate), PEF and poly(ethylene terephthalate), PET, are two polyesters with close chemical structures. It leads to similar thermal, mechanical and barrier properties. In order to optimize their stretching, a strategy based on the time/temperature principle is used. The building of master curves, in the linear visco-elastic domain, allows the identification of the experimental conditions for which the two materials are in the same physical state. The initial physical state of the materials is important as, to fit with the industrial constrains, the polymers must reach high level of deformation, and develop strain induced crystallization (SIC). In this paper, the screening of the forming range is described, as well as the mechanical response depending on the stretching settings. Moreover, the same mechanical response can exist for PEF and PET if the same gap from the α-relaxation exists.
The aim of this study is to develop validated simulations of the stretch blow moulding process. T... more The aim of this study is to develop validated simulations of the stretch blow moulding process. This paper describes experimental studies where a preform is inflated into free air (free blow trials) and the subsequent development of simulations based on the experimental data. The free blow trials were monitored via video and instrumentation was use to measure the pressure vs. time in the process. One of the key conclusions from these trials was that the pressure inside the preform is not an input variable but is in fact an output variable highly dependent on the preform temperature, timing of the application of pressure and the nominal line pressure. This effect was also shown to be hugely significant when considering the development of simulations of the manufacturing process. Two free blow simulations were developed 1: where the pressure was applied directly as measured and 2: where the application of pressure was calculated by the simulation based on a specified flow rate of air. The results clearly sh...
ABSTRACT Intense parasitic nucleation has been observed at the surface of differential scanning c... more ABSTRACT Intense parasitic nucleation has been observed at the surface of differential scanning calorimetry samples for various polymers, whereas their crystallization traces exhibit complex shapes. Revisited overall kinetics theories and computer simulation, taking into account small thickness of samples and transcrystallinity effects, allow to explain and reproduce experimental ‘double peaks’, currently observed with polyamide 6-6. The beginning of the transformation and the main peak are attributed to surface and bulk nucleations, respectively. As a consequence, any DSC experiment should be followed by a microscopic observation and more accurate models including thermal gradients and resistances should be developed for their interpretation. Bei verschiedenen Polymeren wurde an der Oberfläche von DSC-Proben eine intensive parasitäre Keimbildung beobachtet, während ihre Kristallisation komplexe Formen zeigt. Überarbeitete gesamtkinetische Theorien und Computersimulation unter Berücksichtigung dünner Probenstärken und Transkristallinitätseffekte ermöglichen die Deutung und die Reproduzierung experimenteller “Doppelpeaks”, wie sie wie in diesem Falle bei Polyamid 6-6 beobachtet werden. Der Beginn der Umwandlung beziehungsweise der Hauptpeak werden der Keimbildung an der Oberfläche beziehungsweise im Inneren zugeschrieben. Als Folge davon sollten alle DSC-Experimente von einer mikroskopischen Untersuchung gefolgt werden und für deren Interpretation sollten präzisere Modelle unter Einbezug von thermischem Gradient und Widerstand entwickelt werden.
ABSTRACT A general theoretical approach of the overall crystallization kinetics of thin polymer f... more ABSTRACT A general theoretical approach of the overall crystallization kinetics of thin polymer films is developed. This new model makes it possible to calculate the evolution of the transformed volume fraction anywhere in the film, whatever the cooling conditions are. In its isothermal limit this model is equivalent to previous approaches which have been well verified by a computer simulation. In conclusion, it is pointed out that both isothermal and anisothermal determinations of crystallization kinetic parameters are greatly dependent on the sample thickness.
HAL (Le Centre pour la Communication Scientifique Directe), Aug 22, 2021
We implemented a two-step methodology to estimate the residual stresses induced by the FDM manufa... more We implemented a two-step methodology to estimate the residual stresses induced by the FDM manufacturing process in 3D printed composite parts. The first step consisted in an analytical thermo-viscoelastic homogenization procedure to derive the effective behavior of the filament. The second step consisted in a coupled thermomechanical structural analysis of the part. The homogenization procedure was assessed by comparing its predictions to full-field FFT-based computations. The structural analysis was assessed by comparing its predictions to experimental results.
ABSTRACT Within the frame of overall kinetics of crystallization, polymer crystallization is char... more ABSTRACT Within the frame of overall kinetics of crystallization, polymer crystallization is characterized by only three parameters: the initial density of potential nucleiN 0, their activation frequencyq and the growth rateG. The growth rateG is rather easy to measure, whereas the nucleation parameters are generally unknown. Our purpose is to determine bothN 0 andq using experimental isothermal two-dimensional crystallizations and computer simulation. Both these parameters are deduced from the rate of appearance of spherulites expressed as a function of the transformed surface fraction. The activation times of the spherulites are deduced from the shape of the boundaries between spherulites at the end of the transformation. When the growth rateG is known, the evolution of the transformed surface fraction is rebuilt using a computer simulation, so that only one observation of the final stage of the crystallization is needed.
... Patrick et G'sell, Christian et Chevalier, Luc et Gauthier, Christian et Chaigne... more ... Patrick et G'sell, Christian et Chevalier, Luc et Gauthier, Christian et Chaigneau, Richard et Cornillon, Paul et Rauline, Damien. ... Références bibliographiques du chapitre III [1] HARRON, GW, HARKIN-JONES, EMA and MARTIN, PJ, An experimental investigation of the plug ...
The well-known principle of time–temperature superposition (TTS) is of prime interest for polymer... more The well-known principle of time–temperature superposition (TTS) is of prime interest for polymers close to their glass transition. First demonstrated in the range of linear viscoelasticity, it has been more recently extended to large deformations in tension. However, shear tests were not yet addressed. The present study depicted TTS in shearing conditions and compared it to results in tensile conditions both for low and high strains for a polymethylmethacrylate (PMMA) of different molar masses. The main objectives were to enlighten the relevance of the principle of time–temperature superposition for shearing at high strain and to discuss the way shift factors should be determined. It was suggested that shift factors could be dependent on compressibility, which should be taken into account when addressing various types of complex mechanical loadings.
Le travail consigné dans ce mémoire a été réalisé au sein du Centre de Mise en Forme des Matériau... more Le travail consigné dans ce mémoire a été réalisé au sein du Centre de Mise en Forme des Matériaux de l'Ecole des Mines de Paris, à Sophia Antipolis en partenariat avec les sociétés Faurecia, Renault et Visteon dans le cadre d'une thèse CIFRE. Je tiens tout d'abord à exprimer ma gratitude à la direction du laboratoire, ainsi qu'à celle de ces partenaires industriels, pour la confiance qu'ils m'ont accordée. Mes remerciements vont ensuite tout naturellement à Noëlle Billon qui a dirigé ce travail avec beaucoup de rigueur et d'implication. Je tiens à lui témoigner ma profonde reconnaissance pour m'avoir communiqué son enthousiasme pour la recherche et pour m'avoir initié à un sujet passionnant par ses conseils judicieux et des discussions stimulantes au possible. Alain Bürr a par ailleurs largement contribué à l'aboutissement de ce travail et je tiens à lui dire toute ma gratitude. Je voudrais également inclure dans ces remerciements Eric Michau (Faurecia), Jean-christophe Le Flohic (Faurecia), Gregory Spingler (Visteon) et Simon Xu (Renault) pour avoir suivi ce travail jusqu'à son aboutissement. J'ai apprécié la très grande convivialité qu'ils ont mise dans nos rapports. Je souhaite également remercier Jean-François Agassant pour l'intérêt constant qu'il a porté à ma thèse et qui a donné lieu à de nombreux échanges. Je remercie messieurs Jean-Marc Lefebvre et Christophe Fond pour avoir assuré la charge de rapporteurs. Je remercie aussi Jean-Luc Lataillade, André Chrysochoos et Alain Bürr d'avoir accepté de participer au Jury de thèse. J'ai pu apprécier l'intérêt qu'ils ont porté à ce travail par leur participation très active au moment de la soutenance. Je souhaite remercier ici l'ensemble des personnes qui ont contribué à l'aboutissement de ces travaux : Gilbert Fiorucci pour tout le temps qu'il m'a consacré et pour avoir partagé tant de galères, Suzanne pour ton aide et ta bonne humeur, merci également à
The local microstructure and physical properties of an injection moulded PA66 was observed by usi... more The local microstructure and physical properties of an injection moulded PA66 was observed by using combined characterizations. The influence of the manufacturing process on the local structure and mechanical behaviour of the material was analyzed. Interrelations exist but are complex even if it was found that all mechanical properties significantly depend on the location into the material.
The present work can be regarded as a first step toward an integrated modelling of mould filling ... more The present work can be regarded as a first step toward an integrated modelling of mould filling during injection moulding process of polymer matrix composites and the resulting material behaviour under service loading conditions. More precisely, the emphasis of the present research is laid on the development of a mechanical model which takes into account the processing-induced microstructure and is capable to predict the mechanical response of the material. In the Part I, a set of experiments which captures the mechanical behaviour of an injection moulded short fibre reinforced under different strain histories is described. Three mechanical testing are conducted: Dynamic Mechanical Analysis (DMA), uniaxial tension and simple shear. Tests show that the material exhibits complex responses mainly due to non-linearity, anisotropy, time/rate-dependence, hysteresis and permanent strain. Moreover, the relaxed state of the material is characterized by the existence of a so-called anisotropic equilibrium hysteresis independently of the prescribed strain rate.
The present work can be regarded as a first step toward an integrated modelling of mould filling ... more The present work can be regarded as a first step toward an integrated modelling of mould filling during injection moulding process of polymer matrix composites and the resulting material behaviour under service loading conditions. More precisely, the emphasis of the present research is laid on the development of a mechanical model which takes into account the processing-induced microstructure and is capable to predict the mechanical response of the material. In the Part I, a set of experiments which captures the mechanical behaviour of an injection moulded short fibre reinforced under different strain histories is described. Three mechanical testing are conducted: Dynamic Mechanical Analysis (DMA), uniaxial tension and simple shear. Tests show that the material exhibits complex responses mainly due to non-linearity, anisotropy, time/rate-dependence, hysteresis and permanent strain. Moreover, the relaxed state of the material is characterized by the existence of a so-called anisotropic equilibrium hysteresis independently of the prescribed strain rate.
Canadian Journal of Chemical Engineering, Dec 1, 2002
... Billon, N., H. Kappel, S. Crozet, F. Bay, J.-F. Agassant and JM Haudin, “Relations Anisotropi... more ... Billon, N., H. Kappel, S. Crozet, F. Bay, J.-F. Agassant and JM Haudin, “Relations Anisotropie – Propriétés Mécaniques de Tubes ... in Tubular Film and Melt Spinning of Rheologically Characterized High Density, Low Density and Linear Low Density Polyethylene”, J. Non-Newt. ...
Poly(ethylene 2,5-furandicarboxylate), PEF and poly(ethylene terephthalate), PET, are two polyest... more Poly(ethylene 2,5-furandicarboxylate), PEF and poly(ethylene terephthalate), PET, are two polyesters with close chemical structures. It leads to similar thermal, mechanical and barrier properties. In order to optimize their stretching, a strategy based on the time/temperature principle is used. The building of master curves, in the linear visco-elastic domain, allows the identification of the experimental conditions for which the two materials are in the same physical state. The initial physical state of the materials is important as, to fit with the industrial constrains, the polymers must reach high level of deformation, and develop strain induced crystallization (SIC). In this paper, the screening of the forming range is described, as well as the mechanical response depending on the stretching settings. Moreover, the same mechanical response can exist for PEF and PET if the same gap from the α-relaxation exists.
The aim of this study is to develop validated simulations of the stretch blow moulding process. T... more The aim of this study is to develop validated simulations of the stretch blow moulding process. This paper describes experimental studies where a preform is inflated into free air (free blow trials) and the subsequent development of simulations based on the experimental data. The free blow trials were monitored via video and instrumentation was use to measure the pressure vs. time in the process. One of the key conclusions from these trials was that the pressure inside the preform is not an input variable but is in fact an output variable highly dependent on the preform temperature, timing of the application of pressure and the nominal line pressure. This effect was also shown to be hugely significant when considering the development of simulations of the manufacturing process. Two free blow simulations were developed 1: where the pressure was applied directly as measured and 2: where the application of pressure was calculated by the simulation based on a specified flow rate of air. The results clearly sh...
ABSTRACT Intense parasitic nucleation has been observed at the surface of differential scanning c... more ABSTRACT Intense parasitic nucleation has been observed at the surface of differential scanning calorimetry samples for various polymers, whereas their crystallization traces exhibit complex shapes. Revisited overall kinetics theories and computer simulation, taking into account small thickness of samples and transcrystallinity effects, allow to explain and reproduce experimental ‘double peaks’, currently observed with polyamide 6-6. The beginning of the transformation and the main peak are attributed to surface and bulk nucleations, respectively. As a consequence, any DSC experiment should be followed by a microscopic observation and more accurate models including thermal gradients and resistances should be developed for their interpretation. Bei verschiedenen Polymeren wurde an der Oberfläche von DSC-Proben eine intensive parasitäre Keimbildung beobachtet, während ihre Kristallisation komplexe Formen zeigt. Überarbeitete gesamtkinetische Theorien und Computersimulation unter Berücksichtigung dünner Probenstärken und Transkristallinitätseffekte ermöglichen die Deutung und die Reproduzierung experimenteller “Doppelpeaks”, wie sie wie in diesem Falle bei Polyamid 6-6 beobachtet werden. Der Beginn der Umwandlung beziehungsweise der Hauptpeak werden der Keimbildung an der Oberfläche beziehungsweise im Inneren zugeschrieben. Als Folge davon sollten alle DSC-Experimente von einer mikroskopischen Untersuchung gefolgt werden und für deren Interpretation sollten präzisere Modelle unter Einbezug von thermischem Gradient und Widerstand entwickelt werden.
ABSTRACT A general theoretical approach of the overall crystallization kinetics of thin polymer f... more ABSTRACT A general theoretical approach of the overall crystallization kinetics of thin polymer films is developed. This new model makes it possible to calculate the evolution of the transformed volume fraction anywhere in the film, whatever the cooling conditions are. In its isothermal limit this model is equivalent to previous approaches which have been well verified by a computer simulation. In conclusion, it is pointed out that both isothermal and anisothermal determinations of crystallization kinetic parameters are greatly dependent on the sample thickness.
HAL (Le Centre pour la Communication Scientifique Directe), Aug 22, 2021
We implemented a two-step methodology to estimate the residual stresses induced by the FDM manufa... more We implemented a two-step methodology to estimate the residual stresses induced by the FDM manufacturing process in 3D printed composite parts. The first step consisted in an analytical thermo-viscoelastic homogenization procedure to derive the effective behavior of the filament. The second step consisted in a coupled thermomechanical structural analysis of the part. The homogenization procedure was assessed by comparing its predictions to full-field FFT-based computations. The structural analysis was assessed by comparing its predictions to experimental results.
ABSTRACT Within the frame of overall kinetics of crystallization, polymer crystallization is char... more ABSTRACT Within the frame of overall kinetics of crystallization, polymer crystallization is characterized by only three parameters: the initial density of potential nucleiN 0, their activation frequencyq and the growth rateG. The growth rateG is rather easy to measure, whereas the nucleation parameters are generally unknown. Our purpose is to determine bothN 0 andq using experimental isothermal two-dimensional crystallizations and computer simulation. Both these parameters are deduced from the rate of appearance of spherulites expressed as a function of the transformed surface fraction. The activation times of the spherulites are deduced from the shape of the boundaries between spherulites at the end of the transformation. When the growth rateG is known, the evolution of the transformed surface fraction is rebuilt using a computer simulation, so that only one observation of the final stage of the crystallization is needed.
... Patrick et G'sell, Christian et Chevalier, Luc et Gauthier, Christian et Chaigne... more ... Patrick et G'sell, Christian et Chevalier, Luc et Gauthier, Christian et Chaigneau, Richard et Cornillon, Paul et Rauline, Damien. ... Références bibliographiques du chapitre III [1] HARRON, GW, HARKIN-JONES, EMA and MARTIN, PJ, An experimental investigation of the plug ...
The well-known principle of time–temperature superposition (TTS) is of prime interest for polymer... more The well-known principle of time–temperature superposition (TTS) is of prime interest for polymers close to their glass transition. First demonstrated in the range of linear viscoelasticity, it has been more recently extended to large deformations in tension. However, shear tests were not yet addressed. The present study depicted TTS in shearing conditions and compared it to results in tensile conditions both for low and high strains for a polymethylmethacrylate (PMMA) of different molar masses. The main objectives were to enlighten the relevance of the principle of time–temperature superposition for shearing at high strain and to discuss the way shift factors should be determined. It was suggested that shift factors could be dependent on compressibility, which should be taken into account when addressing various types of complex mechanical loadings.
Le travail consigné dans ce mémoire a été réalisé au sein du Centre de Mise en Forme des Matériau... more Le travail consigné dans ce mémoire a été réalisé au sein du Centre de Mise en Forme des Matériaux de l'Ecole des Mines de Paris, à Sophia Antipolis en partenariat avec les sociétés Faurecia, Renault et Visteon dans le cadre d'une thèse CIFRE. Je tiens tout d'abord à exprimer ma gratitude à la direction du laboratoire, ainsi qu'à celle de ces partenaires industriels, pour la confiance qu'ils m'ont accordée. Mes remerciements vont ensuite tout naturellement à Noëlle Billon qui a dirigé ce travail avec beaucoup de rigueur et d'implication. Je tiens à lui témoigner ma profonde reconnaissance pour m'avoir communiqué son enthousiasme pour la recherche et pour m'avoir initié à un sujet passionnant par ses conseils judicieux et des discussions stimulantes au possible. Alain Bürr a par ailleurs largement contribué à l'aboutissement de ce travail et je tiens à lui dire toute ma gratitude. Je voudrais également inclure dans ces remerciements Eric Michau (Faurecia), Jean-christophe Le Flohic (Faurecia), Gregory Spingler (Visteon) et Simon Xu (Renault) pour avoir suivi ce travail jusqu'à son aboutissement. J'ai apprécié la très grande convivialité qu'ils ont mise dans nos rapports. Je souhaite également remercier Jean-François Agassant pour l'intérêt constant qu'il a porté à ma thèse et qui a donné lieu à de nombreux échanges. Je remercie messieurs Jean-Marc Lefebvre et Christophe Fond pour avoir assuré la charge de rapporteurs. Je remercie aussi Jean-Luc Lataillade, André Chrysochoos et Alain Bürr d'avoir accepté de participer au Jury de thèse. J'ai pu apprécier l'intérêt qu'ils ont porté à ce travail par leur participation très active au moment de la soutenance. Je souhaite remercier ici l'ensemble des personnes qui ont contribué à l'aboutissement de ces travaux : Gilbert Fiorucci pour tout le temps qu'il m'a consacré et pour avoir partagé tant de galères, Suzanne pour ton aide et ta bonne humeur, merci également à
The local microstructure and physical properties of an injection moulded PA66 was observed by usi... more The local microstructure and physical properties of an injection moulded PA66 was observed by using combined characterizations. The influence of the manufacturing process on the local structure and mechanical behaviour of the material was analyzed. Interrelations exist but are complex even if it was found that all mechanical properties significantly depend on the location into the material.
The present work can be regarded as a first step toward an integrated modelling of mould filling ... more The present work can be regarded as a first step toward an integrated modelling of mould filling during injection moulding process of polymer matrix composites and the resulting material behaviour under service loading conditions. More precisely, the emphasis of the present research is laid on the development of a mechanical model which takes into account the processing-induced microstructure and is capable to predict the mechanical response of the material. In the Part I, a set of experiments which captures the mechanical behaviour of an injection moulded short fibre reinforced under different strain histories is described. Three mechanical testing are conducted: Dynamic Mechanical Analysis (DMA), uniaxial tension and simple shear. Tests show that the material exhibits complex responses mainly due to non-linearity, anisotropy, time/rate-dependence, hysteresis and permanent strain. Moreover, the relaxed state of the material is characterized by the existence of a so-called anisotropic equilibrium hysteresis independently of the prescribed strain rate.
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