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October 2012 - present
January 2008 - October 2012
Publications
Publications (80)
The phase transformation and densification behaviors are two critical research topics in the semi-crystalline polymer Laser Powder Bed Fusion (L-PBF) process. This study first introduces a thermal model incorporating crystallization kinetics to study the temperature evolution and phase transformation behavior during the L-PBF of polyamide-12 (PA12)...
The thermal expansion behavior of polymers is a crucial property for manufacturing photovoltaic (PV) modules. The thermal expansion mismatch between the different module components induces residual stresses in the structure after manufacturing. Some of them are located at the interface between materials, leading to delamination and reliability issu...
Citation: Viora, L.; Combeau, M.; Pucci, M.F.; Perrin, D.; Liotier, P.-J.; Bouvard, J.-L.; Combeaud, C. A Comparative Study on Crystallisation for Virgin and Recycled Polyethylene Terephthalate (PET): Multiscale Effects on Physico-Mechanical Properties. Polymers 2023, 15, 4613. https:// Abstract: Poly(Ethylene Terephthalate) (PET) is one of the mos...
A particle scale numerical model of laser powder bed fusion (L-PBF) for semi-crystalline polymer PA12 is presented in this work. The model is developed by the finite element method under the framework of the level-set method. The asymmetrical and kinetical thermal behavior of semi-crystalline polymer is implemented in the thermal model, enabling be...
This paper deals with the viscoelastic behavior during crystallization and melting of semicrystalline polymers, with the aim of later modeling the residual stresses after processing in cases where crystallization occurs in quasi-static conditions (in additive manufacturing for example). Despite an abundant literature on polymer crystallization, the...
Polyethylene terephthalate (PET) is nowadays one of the most used polymers for packaging applications. Modifications induced by service conditions and the optimal mean to recycle this matter several times have to be perfectly understood to allow a reuse for similar application (from bottle to bottle for example). The present study aims to compare p...
The microstructural evolutions occurring during the thermo-hydro-glycol ageing of an injection molded PA66 were studied. They were correlated to the evolutions of its mechanical properties. The aged samples were immersed in an antifreeze fluid—mainly composed of water and ethylene glycol—at varying times and temperatures. The aim was to combine an...
Biodegradable anisotropic neat porous starch materials without any additional cross-linking, plasticizer or any extra matter have been fabricated via facile ice-templating method. Waxy maize was dissolved in water followed by unidirectional freezing and ice sublimation. The influence of process parameters (starch concentration and retrogradation ti...
The aim of this work consists in estimating and modeling the viscoelastic behavior at small strain of KetaSpire® KT-880 PEEK fiber composites reinforced with short glass fibers. The viscoelastic behavior of the PEEK matrix is identified from a series of DMA tests at different temperatures. The principle of time–temperature superposition is used to...
Assessment of the effect of the lamination process parameters on the reliability of PV modules is a key step
to extend their lifetime. In this work, a new method of measurement of the deflection PV modules is presented. This method
consists in mapping the surface of both sides of a PV module positioned on 4-point supports. The measurement repetitio...
The following study aims in describing the impact of the architecture of the photovoltaic (PV) module and lamination recipe on the thermal exchange between the laminator and the PV module for different configurations. First, the PV module temperature evolution was measured during the lamination process, using temperature sensors. These temperature...
All-cellulose composites (ACCs) were prepared from filter paper via partial dissolution in the ionic liquid 1-ethyl-3-methylimidazolium acetate, and material tensile properties were investigated using various approaches. One is based on data directly taken from a tensile testing machine, and the other uses two-cameras stereovision with digital imag...
The main purpose of this study is to better understand the relationship between the microstructure of foamed polymer and mechanical properties. X-Ray tomography was performed on polypropylene foam specimens machined from injected plates. These plates were obtained for different thicknesses and exhibit different microstructure morphologies. The tomo...
The effect of the strain rate on damage in carbon black filled Ethylene Propylene Diene Monomer rubber (EPDM)stretched during single and multiple uniaxial loading is investigated. This has been performed by analyzing the stress-strain response, the evolution of damage by Digital Image Correlation (DIC), the associated dissipative heat source by Inf...
The effect of the strain rate on damage in carbon black filled EPDM stretched during single and multiple uniaxial loading is investigated. This has been performed by analysing the stress-strain response, the evolution of damage by Digital Image Correlation (DIC), the associated dissipative heat source by InfraRed thermography (IR), and the chains n...
The thermomechanical coupling of Mullins damage in filled EPDM has been investigated by analysing the self-heating via Infrared thermography (IR) and the voiding fraction by Digital Image Correlation (DIC). The volumetric strain measured during the rubber deformation is found to be predominantly associated with damage, while thermal dilatation caus...
The potential and the interest of the development of mechanical approach based on concepts issued from the physics of polymers, as well as of the use of the time temperature equivalence principle, are illustrated. To achieve that point, a revisited constitutive model [1], [2] was used to model the mechanical behaviour of amorphous PMMA with differe...
Chains and filler network damage were investigated during single and multiple cycles on a series of vulcanized EPDM containing various filler contents. In both series of experiments, a strain and a filler ratio transitions for damage mechanisms were identified. For low filler content (≤40 phr), damage mechanisms mostly occur in the elastically acti...
Highly porous and lightweight cellulose materials were prepared via dissolution–coagulation and different drying routes. Cellulose of three different molecular weights was dissolved in ionic liquid/dimethyl sulfoxide mixture. Drying was performed either with supercritical CO2 resulting in “aerogels”, or via freeze-drying resulting in “cryogels”. Th...
May it be for environmental or economic reasons, mass reduction has become one of the main goals in mechanics. The short fiber thermoplastics composite is an interesting possibility since it presents a good compromise between a relatively easy process and mechanical properties. The aim of this work is to estimate and model the viscoelastic behavior...
Clear relationships between the semi-crystalline microstructure of injection molding polymers and their mechanical behavior are not yet totally established for all polymers. Part of this relative lack of understanding is because an unambiguous scientific approach is difficult to build up. The processing of samples promotes a microstructure which is...
The relevance of equivalent strain rate at reference temperature derived from time/temperature superposition principle is validated as a constitutive parameter at large strain for PMMAs of different chain architecture. Shift factors were obtained from DMTA at infinitesimal strain, then identified according to Williams-Landel-Ferry or Arrhenius equa...
This research addresses the effects of quasi-UD non-crimp fabric (NCF) design parameters on the fabric architecture and on the permeability tensor. These fabrics are designed for the Liquid Resin Infusion (LRI) of large and thick composite parts. Three fabrics’ parameters intended to bring a flow enhancement to the NCF are investigated: the stitch...
Revisited network theory to account for inelasticity1,2 was used to model behavior of amorphous and semicrystalline PET. Semicrystalline materials were obtained through cold crystallization of the amorphous one making the crystalline microstructure the only difference. The model considers microstructure at a mesoscopic level through the description...
We present a general internal state variable (ISV) elastic-viscoplastic constitutive model that was initially applied to amorphous polymers (Bouvard et al J Eng Mater Technol 131(4), 041206, 2013) but has been extended to apply to semi-crystalline polymers along with a fracture criterion. In this work, we experimentally calibrated and validated the...
Ethylene-propylene-diene-monomer rubber (EPDM) has been widely studied in the recent years. Thanks to its high resistance to ageing and mechanical properties, it is one of the best candidates for the automotive industry. For a better understanding of its mechanical properties, a suitable characterization of its thermomechanical behavior is mandator...
A split-level factorial design of experiments (DOE) parametric study using a two-dimensional mesoscale Finite Element Analysis (FEA) was executed to elicit the most essential aspects pertaining to void/crack growth and void/crack coalescence in polymers above the glass transition temperature. The FEA was coupled to a physically based, strain rate a...
Cet article illustre la diversité des comportements des matières plastiques en s'appuyant sur un choix de caractérisations expérimentales. Quelques règles générales sont déduites. Des conseils quant aux protocoles de mesures sont décrits et justifiés. L'intérêt se porte essentiellement sur la viscoélasticité, les effets de températures, de vitesse...
A visco-hyperelastic constitutive model, based on an original approach initially developed by (Billon, 2012) and applied to amorphous rubbery polymers for a one-dimensional formalism, was extended in this study to three-dimensional constitutive equations based on a thermodynamic framework. The model was applied to a semi-crystalline polyamide polym...
Carbon black filled ethylene-propylene-diene-monomer (EPDM) has been widely studied in the recent years. Thanks to its good electrical properties, high resistance to ageing and mechanical properties, it is one of the best candidates for the automotive industry. The improvement of its mechanical properties should be based on a good understanding of...
In this article, we experimentally investigate the structure–property relationships of an acrylonitrile butadiene styrene (ABS) copolymer for fatigue and use a microstructure-based multistage fatigue (MSF) model to predict material failure. The MSF model comprises three stages of fatigue damage (crack incubation, small crack growth, and long crack...
The following article proposes a damage model that is implemented into a glassy, amorphous thermoplastic thermomechanical inelastic internal state variable framework. Internal state variable evolution equations are defined through thermodynamics, kinematics, and kinetics for isotropic damage arising from two different inclusion types: pores and par...
Molecular dynamics simulations are increasingly being used to investigate the
structural evolution of polymers during mechanical deformation, but relatively
few studies focus on the influence of boundary conditions on this evolution, in
particular the dissipation of both heat and pressure through the periodic
boundaries during deformation. The rese...
The thermal decomposition behavior of styrene-butadiene rubber was studied using a system equipped with thermogravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, and mass spectroscopy. Two different experiments were conducted. From these experiments, thermogravimetric analysis results indicated a mass loss...
a b s t r a c t This paper presents a complete theoretical accounting of the thermomechanical coupling within a viscoplastic model to predict the time, temperature, and stress state dependent mechanical behavior of amorphous glassy polymers. The foundational model formulation (Bouvard et al., 2010), developed to predict the time dependent behavior...
L’objet de cette étude est de développer une méthodologie de simulation numérique de propagation de fissure par fatigue, en appliquant une approche couplée. On s’intéresse plus particulièrement à l’utilisation d’éléments d’interface cohésifs, avec une loi de comportement spécifique, afin de simuler, sans discontinuité, et avec un caractère prédicti...
a b s t r a c t This paper presents the formulation of a phenomenological model to predict the crack growth in single crystal superalloy at high temperature. The proposed model relies on an extensive experimental study performed on AM1 single crystal superalloy at temperatures ranging from 650 °C to 950 °C. Tests carried out in fatigue and creep–fa...
This paper presents a coupled experimental/modeling study of the mechanical response of porcine brain under high strain rate loading conditions. Essentially, the stress wave propagation through the brain tissue is quantified. A Split-Hopkinson Pressure Bar (SPHB) apparatus, using a polycarbonate (viscoelastic) striker bar was employed for inducing...
The use of lighter and impact resistant materials, such as polymers, in vehicular systems is an important motivation for the automotive industry as these materials would make vehicles more fuel-efficient without compromising safety standards. In general, polymers exhibit a rich variety of material behavior originating from their particular microstr...
The molecular origin of plastic deformation within amorphous polymers is an important issue that is still not well understood. Here, we investigate the deformation mechanisms of amorphous polyethylene. Molecular dynamics simulations were used to apply a tensile load to amorphous polyethylene using a united atom model. A range of strain rates, chain...
The use of lighter and impact resistant materials, such as polymers, in vehicular systems is an important motivation for the
automotive industry as these materials would make vehicles more fuel-efficient without compromising safety standards. In general,
polymers exhibit a rich variety of material behavior originating from their particular microstr...
Résumé : Les résultats présentés dans ce travail concernent la mise en place d'une base de données matériau pour trois différents thermoplastiques: le polycarbonate, le polypropylene et l'acrylonitrile-butadiene-styrene. Des essais mécaniques de compression et traction ont été menés à différentes vitesses de déformation afin de caractériser leur co...
In this study, a styrene butadiene rubber, which is similar to the rubber used in road wheel backer pads of tracked vehicles, was investigated experimentally under monotonic and fatigue loading conditions. The monotonic loading response of the material was obtained under different stress states (compression and tension), strain rates (0.001/s to 30...
Overview of report: Monotonic approach: Internal state variable (ISV) model for metals; ISV modeling strategy moved to glassy polymers and current efforts to apply ISV modeling strategy to elastomers. Fatigue approach: Researchers have historically separated fatigue crack initiation and propagation, (McDowell et al., 2003) refined the earlier crack...
This paper presents the formulation of a constitutive model for amorphous thermoplastics using a thermodynamic approach with
physically motivated internal state variables. The formulation follows current internal state variable methodologies used
for metals and departs from the spring-dashpot representation generally used to characterize the mechan...
Modern computational methods have proved invaluable for the design and analysis of structural components using lightweight materials. The challenge of optimizing light-weight materials in the design of industrial components relates to incorporating structure-property relationships within the computational strategy to incur robust de-signs. One effe...
A numerical analysis using cohesive zone model under cyclic loading is proposed to develop a coupled predictive approach of crack growth in single crystal. The process of material damage during fatigue crack growth is described using an irreversible cohesive zone model, which governs the separation of the crack flanks and eventually leads to the fo...
In this study, we examine the transverse and longitudinal compressive mechanical behavior of the rabbit patellar tendon. The anisotropic compressive properties are of interest, because compression occurs where the tendon attaches to bone and where the tendon wraps around bone leading to the development of fibro-cartilaginous matrices. We quantified...
In this study, a numerical method is developped to simulate fatigue crack growth. This method is based on a numerical coupled analysis using a cohesive zone modelling under cyclic loading in order to develop a coupled predictive approach of the crack growth. First, we present this damage law, then its validation by a convergence study of the soluti...
L'objectif de ce travail a tout d'abord été de développer une méthodologie de simulation numérique de propagation de fissure, en appliquant une approche couplée en chargement cyclique. On s'est intéressé, plus particulièrement, à l'utilisation d'éléments de zones cohésives couplés à une loi de comportement spécifique, afin de simuler, sans disconti...
In blading components, a large proportion of service life is taken up in initiating and growing surface or near surface short
cracks through the Stage I fatigue regime, that is when the crack length is small compared to the scale of the crack tip plasticity.
Finite element simulations of the propagation of small cracks were performed using crystal plasticity constitutive equations in order to have a better understanding of closure/opening phenomena induced by the plasticity confined at the crack tip. Two numerical methods can be applied to simulate the crack growth : • A node release technique performe...
L'objectif de ce travail a tout d'abord été de développer une méthodologie de simulation numérique de propagation de fissure, en appliquant une approche couplée en chargement cyclique. On s'est intéressé, plus particulièrement, à l'utilisation d'éléments de zones cohésives couplés à une loi de comportement spécifique, afin de simuler, sans disconti...
Les résultats présentés concernent la mise en place d’une base de données matériau pour trois différents thermoplastiques: le polycarbonate, le polypropylene et ABS. Des essais de compression, traction et torsion ont été menés à différentes vitesses de déformation et températures afin de caractériser leur comportement mécanique. Une loi de comporte...
