Ida Raoult - Academia.edu (original) (raw)
Papers by Ida Raoult
Procedia Structural Integrity, 2022
L'invention porte sur un ensemble de structure (1) pour vehicule automobile, du type comprena... more L'invention porte sur un ensemble de structure (1) pour vehicule automobile, du type comprenant, d'une part, une coupelle (2) de support superieur pour un systeme de suspension d'une roue et, d'autre part, une paroi de passage de roue (3) pour ladite roue. Cet ensemble de structure (1) est remarquable en ce que la coupelle (2) et la paroi de passage sont realisees d'un seul tenant sous la forme d'une piece monobloc dans un materiau polymere thermoplastique, notamment du type polypropylene. La presente invention trouve une application dans le domaine automobile.
In an automobile structure, a spot weld (SW) is a pointwise connection element where stress conce... more In an automobile structure, a spot weld (SW) is a pointwise connection element where stress concentrations occur. Therefore, the region will be particularly exposed to fatigue failures, and a SW model for fatigue analysis is necessary. However, the large number of Spot welds (from 4000 to 6000) requires this SW model to be simplified. Multiple models have been developped to reproduce the SW behavior within a structur. They are mostly phenomenological and with a minimum numerical cost. Therefore, these models are limited. The purpose of this study is thus to propose an accurate model of connector (i.e. with a strong physical meaning, a wide domain of applications), that is based on a methodology adapted to the industrial constraints as a reasonable numerical cost. First, it is necessary to identify the Mechanical Influence Area (MIA) of the SW. In other words, the zone where 3D edge effects spreading around the connec-tor are leading to a no longer valid shell theory. Second, the dev...
The invention relates to a method for manufacturing a suspension spring particularly for motor ve... more The invention relates to a method for manufacturing a suspension spring particularly for motor vehicles, formed from a composite material including fibers and resin. According to the invention, the method comprises on the same manufacturing steps of die: - making a core (2) for supporting the fibers, - fabricating a yarn comprising at least one layer of fibers wound around the central core (2) shaping of the wire around a mandrel (5) driven in a rotational movement by the wire as and when it is formed and solidification thereof in a helical shape.
Ces travaux ont ete realises dans le cadre d'une these CIFRE entre le groupe PSA et le LMT. R... more Ces travaux ont ete realises dans le cadre d'une these CIFRE entre le groupe PSA et le LMT. Resume-Cette etude propose d'investiguer les ingredients indispensables a l'elaboration d'un modele de connecteur representatif du comportement d'un Point de Soudure Electrique (PSE). Ce connecteur est destine a relier des structures modelisees par des plaques ou des coques. Ainsi, on se concentre ici sur l'etude de la dimension de la zone ou la theorie des plaques epaisses n'est plus valide. On s'appuie pour cela sur des quantites d'interet revelant cette limite de validite des elements proches du PSE. Differentes configurations sont testees, faisant varier le type de sollicitation et la geometrie. Dans un deuxieme temps, la recherche de la cinematique locale dans la zone du PSE est egalement evoquee. Mots cles-Modele reduit, connecteur, approche globale/locale.
MATEC Web of Conferences, 2019
Industrial structures undergo complex loading often unsuitable for the design and validation phas... more Industrial structures undergo complex loading often unsuitable for the design and validation phases of their development. Engineers seek simplified signals to replace them, yet equivalent in terms of fatigue. A general framework for the construction of fatigue equivalent loads is presented, intended to take into account some uncertainty on the structure to which it will apply. The guiding idea is to describe this uncertainty thanks to parameters of a model of the structure, and then to assure the equivalence of damage or failure behavior over the whole range of expected parameters. The approach is applied in the case of structures undergoing multiple inputs of concentrated force.
MATEC Web of Conferences, 2018
Relations between existing spot-weld finite element models and the mechanical behaviour of spot-w... more Relations between existing spot-weld finite element models and the mechanical behaviour of spot-weld are investigated for fatigue design application. Specifically, the different zones that constitute the numerical model are interrogated with respect to physical observation. In order to identify the Mechanical Influence Area of the Spot-Weld here designated as "MIASW" we propose a methodology to determine numerically its size. Hence, we develop a finite element coupon representing a spot-weld under a basis of four unit load cases. The coupon provides mechanical quantities of interest that allows us to characterize the spot-weld response that shell element are unable to represent. This response is crucial to be captured for further fatigue analysis.
Fatigue & Fracture of Engineering Materials & Structures
International Journal of Fatigue
Procedia Engineering, 2010
Fatigue life prediction of polymer matrix composites requires the investigation of the cyclic beh... more Fatigue life prediction of polymer matrix composites requires the investigation of the cyclic behavior. This paper deals with the experimental study conducted on a polyamide 66 reinforced with 35 wt% of short glass fibers (PA66 GF35), at room temperature. The material was tested dry-as-molded or at the equilibrium with an air containing 50 % of relative humidity. The dynamic mechanical analysis leads us to focus on the material conditioned at RH=50 %, which appears to exhibit the most complex mechanical effects, and is yet representative of the actual service life. An exhaustive experimental campaign in tensile mode has been carried out, including various strain or stress rates, complex mechanical histories and local thermo-mechanical recording. The material has thus been tested in static tension at stress rates ranging over four decades (from 2.5 to 2500 MPa/s), and also in cyclic tension with loading histories combining creep, stress relaxation or strain recovery steps at different strain/stress levels. Such an extended database allowed us to highlight several mechanical phenomena: at least two characteristic viscous times co-exist, and are independent of any irreversible mechanism. Residual strain appears above a stress threshold, and a kinematic hardening law is suggested to explain tension-relaxation-recovery tests. Eventually, hints of a non-linear viscous flow law and of a cyclic damage law are pointed out.
Procedia Engineering, 2011
ABSTRACT SGFR thermoplastics exhibit a highly non-linear mechanical behavior under complex mechan... more ABSTRACT SGFR thermoplastics exhibit a highly non-linear mechanical behavior under complex mechanical loadings, for various temperature and humidity conditions. A phenomenological constitutive model is proposed; describing several physical mechanisms such as viscoelasticity, thresholdless viscoplasticity and cyclic softening. The anisotropic microstructure resulting from the injection process is taken into account through orientation tensors. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of ICM11
L'industrie automobile utilise de nombreuses pièces en caoutchouc aux fonctions antivibratoir... more L'industrie automobile utilise de nombreuses pièces en caoutchouc aux fonctions antivibratoires, dont il faut garantir la tenue en service. L'objectif de ce travail de thèse est de proposer une méthode pour prévoir la durée de vie en fatigue d'une structure en caoutchouc naturel chargé au noir de carbone. La démarche proposée consiste à découpler l'évolution du comportement mécanique et l'endommagement sous chargement cyclique. On suppose qu'il existe un cycle stabilisé et que la durée de vie, définie comme l'amorçage d'une fissure détectable, ne dépend que des grandeurs mécaniques évaluées sur celui-ci. Les élastomères soumis à un chargement cyclique présentent un adoucissement associé à l'effet Mullins, qui se produit surtout pendant les premiers cycles, après lesquels la réponse du matériau reste identique. On propose un modèle capable de décrire cette réponse stabilisée, ne dépendant que des variables mécaniques en régime établi. Ses paramètre...
Short Glass Fibre Reinforced Polyamide 6.6 composites are increasingly used in structural automot... more Short Glass Fibre Reinforced Polyamide 6.6 composites are increasingly used in structural automotive applications. The resulting fibre distribution within injection-moulded components has a major impact on their mechanical properties due to the complex flow path taking place while filling the mould. Even for simple structural geometries, resulting mechanical fields are heterogeneous. Moreover, the mechanical behaviour of polyamide composites is sensitive to mechanical loads and especially to environmental hygrothermal conditions. In this work, we propose to use Infrared Thermography to monitor heterogeneous energy dissipation during tensile tests for different PA66GF35 specimens with non uniform fibre distributions. In addition, Launay's thermoelasto-viscoplastic constitutive model was used to simulate temperature evolution during the tests. It is shown that particular attention must be paid to improve filling particles distribution considerations for a right prediction of therm...
The current work presents a new contribution to the phenomenological modeling of mechanical fatig... more The current work presents a new contribution to the phenomenological modeling of mechanical fatigue damage in short glass fiber reinforced thermoplastic matrix composites for PA66-GF35. The majority of Injection Simulation Softwares are not able to predict a realistic orientation and repartition of fibers in the corner or flange of complex component such as in the automotive parts. The first part of this work is to implement the experimental distribution of short glass fiber in order to simulate realistic fatigue damage for GFRP. For this reason, Micro X-ray tomography is used to characterize the repartition and the orientation of glass fiber in critical area of the automotive part (flange, corner ...). The fatigue damage model used in this work is developed by Nouri et al [1]. (NML) in order to simulate the fatigue damage in glass fiber reinforced plastics GFRP. This model is able to predict the three damage stages observed during cycling loading of thermoplastics composite reinforced by glass fiber: i) onset of the damage, ii) coalescence of microcracks and propagation, iii) macroscopic cracks propagation and material failure. Glass fiber orientation and repartition obtained by X-ray tomography is used to create Abaqus cae file for automotive part. The model is implemented via Umat into Abaqus. The model parameters are identified using an inverse strategy with one single specimen based on heterogeneous fatigue tests. It consists on the use of optical whole-field displacement/strain measurements (digital image correlation) coupled to an inverse method from one single coupon. It is worth noting that the mechanical test must give rise to heterogeneous stress/strain fields. Indeed, in this case, the constitutive parameters are expected to be all involved in the response of the specimen.
Procedia Structural Integrity, 2022
L'invention porte sur un ensemble de structure (1) pour vehicule automobile, du type comprena... more L'invention porte sur un ensemble de structure (1) pour vehicule automobile, du type comprenant, d'une part, une coupelle (2) de support superieur pour un systeme de suspension d'une roue et, d'autre part, une paroi de passage de roue (3) pour ladite roue. Cet ensemble de structure (1) est remarquable en ce que la coupelle (2) et la paroi de passage sont realisees d'un seul tenant sous la forme d'une piece monobloc dans un materiau polymere thermoplastique, notamment du type polypropylene. La presente invention trouve une application dans le domaine automobile.
In an automobile structure, a spot weld (SW) is a pointwise connection element where stress conce... more In an automobile structure, a spot weld (SW) is a pointwise connection element where stress concentrations occur. Therefore, the region will be particularly exposed to fatigue failures, and a SW model for fatigue analysis is necessary. However, the large number of Spot welds (from 4000 to 6000) requires this SW model to be simplified. Multiple models have been developped to reproduce the SW behavior within a structur. They are mostly phenomenological and with a minimum numerical cost. Therefore, these models are limited. The purpose of this study is thus to propose an accurate model of connector (i.e. with a strong physical meaning, a wide domain of applications), that is based on a methodology adapted to the industrial constraints as a reasonable numerical cost. First, it is necessary to identify the Mechanical Influence Area (MIA) of the SW. In other words, the zone where 3D edge effects spreading around the connec-tor are leading to a no longer valid shell theory. Second, the dev...
The invention relates to a method for manufacturing a suspension spring particularly for motor ve... more The invention relates to a method for manufacturing a suspension spring particularly for motor vehicles, formed from a composite material including fibers and resin. According to the invention, the method comprises on the same manufacturing steps of die: - making a core (2) for supporting the fibers, - fabricating a yarn comprising at least one layer of fibers wound around the central core (2) shaping of the wire around a mandrel (5) driven in a rotational movement by the wire as and when it is formed and solidification thereof in a helical shape.
Ces travaux ont ete realises dans le cadre d'une these CIFRE entre le groupe PSA et le LMT. R... more Ces travaux ont ete realises dans le cadre d'une these CIFRE entre le groupe PSA et le LMT. Resume-Cette etude propose d'investiguer les ingredients indispensables a l'elaboration d'un modele de connecteur representatif du comportement d'un Point de Soudure Electrique (PSE). Ce connecteur est destine a relier des structures modelisees par des plaques ou des coques. Ainsi, on se concentre ici sur l'etude de la dimension de la zone ou la theorie des plaques epaisses n'est plus valide. On s'appuie pour cela sur des quantites d'interet revelant cette limite de validite des elements proches du PSE. Differentes configurations sont testees, faisant varier le type de sollicitation et la geometrie. Dans un deuxieme temps, la recherche de la cinematique locale dans la zone du PSE est egalement evoquee. Mots cles-Modele reduit, connecteur, approche globale/locale.
MATEC Web of Conferences, 2019
Industrial structures undergo complex loading often unsuitable for the design and validation phas... more Industrial structures undergo complex loading often unsuitable for the design and validation phases of their development. Engineers seek simplified signals to replace them, yet equivalent in terms of fatigue. A general framework for the construction of fatigue equivalent loads is presented, intended to take into account some uncertainty on the structure to which it will apply. The guiding idea is to describe this uncertainty thanks to parameters of a model of the structure, and then to assure the equivalence of damage or failure behavior over the whole range of expected parameters. The approach is applied in the case of structures undergoing multiple inputs of concentrated force.
MATEC Web of Conferences, 2018
Relations between existing spot-weld finite element models and the mechanical behaviour of spot-w... more Relations between existing spot-weld finite element models and the mechanical behaviour of spot-weld are investigated for fatigue design application. Specifically, the different zones that constitute the numerical model are interrogated with respect to physical observation. In order to identify the Mechanical Influence Area of the Spot-Weld here designated as "MIASW" we propose a methodology to determine numerically its size. Hence, we develop a finite element coupon representing a spot-weld under a basis of four unit load cases. The coupon provides mechanical quantities of interest that allows us to characterize the spot-weld response that shell element are unable to represent. This response is crucial to be captured for further fatigue analysis.
Fatigue & Fracture of Engineering Materials & Structures
International Journal of Fatigue
Procedia Engineering, 2010
Fatigue life prediction of polymer matrix composites requires the investigation of the cyclic beh... more Fatigue life prediction of polymer matrix composites requires the investigation of the cyclic behavior. This paper deals with the experimental study conducted on a polyamide 66 reinforced with 35 wt% of short glass fibers (PA66 GF35), at room temperature. The material was tested dry-as-molded or at the equilibrium with an air containing 50 % of relative humidity. The dynamic mechanical analysis leads us to focus on the material conditioned at RH=50 %, which appears to exhibit the most complex mechanical effects, and is yet representative of the actual service life. An exhaustive experimental campaign in tensile mode has been carried out, including various strain or stress rates, complex mechanical histories and local thermo-mechanical recording. The material has thus been tested in static tension at stress rates ranging over four decades (from 2.5 to 2500 MPa/s), and also in cyclic tension with loading histories combining creep, stress relaxation or strain recovery steps at different strain/stress levels. Such an extended database allowed us to highlight several mechanical phenomena: at least two characteristic viscous times co-exist, and are independent of any irreversible mechanism. Residual strain appears above a stress threshold, and a kinematic hardening law is suggested to explain tension-relaxation-recovery tests. Eventually, hints of a non-linear viscous flow law and of a cyclic damage law are pointed out.
Procedia Engineering, 2011
ABSTRACT SGFR thermoplastics exhibit a highly non-linear mechanical behavior under complex mechan... more ABSTRACT SGFR thermoplastics exhibit a highly non-linear mechanical behavior under complex mechanical loadings, for various temperature and humidity conditions. A phenomenological constitutive model is proposed; describing several physical mechanisms such as viscoelasticity, thresholdless viscoplasticity and cyclic softening. The anisotropic microstructure resulting from the injection process is taken into account through orientation tensors. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of ICM11
L'industrie automobile utilise de nombreuses pièces en caoutchouc aux fonctions antivibratoir... more L'industrie automobile utilise de nombreuses pièces en caoutchouc aux fonctions antivibratoires, dont il faut garantir la tenue en service. L'objectif de ce travail de thèse est de proposer une méthode pour prévoir la durée de vie en fatigue d'une structure en caoutchouc naturel chargé au noir de carbone. La démarche proposée consiste à découpler l'évolution du comportement mécanique et l'endommagement sous chargement cyclique. On suppose qu'il existe un cycle stabilisé et que la durée de vie, définie comme l'amorçage d'une fissure détectable, ne dépend que des grandeurs mécaniques évaluées sur celui-ci. Les élastomères soumis à un chargement cyclique présentent un adoucissement associé à l'effet Mullins, qui se produit surtout pendant les premiers cycles, après lesquels la réponse du matériau reste identique. On propose un modèle capable de décrire cette réponse stabilisée, ne dépendant que des variables mécaniques en régime établi. Ses paramètre...
Short Glass Fibre Reinforced Polyamide 6.6 composites are increasingly used in structural automot... more Short Glass Fibre Reinforced Polyamide 6.6 composites are increasingly used in structural automotive applications. The resulting fibre distribution within injection-moulded components has a major impact on their mechanical properties due to the complex flow path taking place while filling the mould. Even for simple structural geometries, resulting mechanical fields are heterogeneous. Moreover, the mechanical behaviour of polyamide composites is sensitive to mechanical loads and especially to environmental hygrothermal conditions. In this work, we propose to use Infrared Thermography to monitor heterogeneous energy dissipation during tensile tests for different PA66GF35 specimens with non uniform fibre distributions. In addition, Launay's thermoelasto-viscoplastic constitutive model was used to simulate temperature evolution during the tests. It is shown that particular attention must be paid to improve filling particles distribution considerations for a right prediction of therm...
The current work presents a new contribution to the phenomenological modeling of mechanical fatig... more The current work presents a new contribution to the phenomenological modeling of mechanical fatigue damage in short glass fiber reinforced thermoplastic matrix composites for PA66-GF35. The majority of Injection Simulation Softwares are not able to predict a realistic orientation and repartition of fibers in the corner or flange of complex component such as in the automotive parts. The first part of this work is to implement the experimental distribution of short glass fiber in order to simulate realistic fatigue damage for GFRP. For this reason, Micro X-ray tomography is used to characterize the repartition and the orientation of glass fiber in critical area of the automotive part (flange, corner ...). The fatigue damage model used in this work is developed by Nouri et al [1]. (NML) in order to simulate the fatigue damage in glass fiber reinforced plastics GFRP. This model is able to predict the three damage stages observed during cycling loading of thermoplastics composite reinforced by glass fiber: i) onset of the damage, ii) coalescence of microcracks and propagation, iii) macroscopic cracks propagation and material failure. Glass fiber orientation and repartition obtained by X-ray tomography is used to create Abaqus cae file for automotive part. The model is implemented via Umat into Abaqus. The model parameters are identified using an inverse strategy with one single specimen based on heterogeneous fatigue tests. It consists on the use of optical whole-field displacement/strain measurements (digital image correlation) coupled to an inverse method from one single coupon. It is worth noting that the mechanical test must give rise to heterogeneous stress/strain fields. Indeed, in this case, the constitutive parameters are expected to be all involved in the response of the specimen.