References of "Flores, Paulo"
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See detailRemarkably low genetic diversity and strong population structure in common bottlenose dolphins (Tursiops truncatus) from coastal waters of the Southwestern Atlantic Ocean
Fruet, Pedro; Secchi, Eduardo; Daura-Jorge, Fabio et al

in Conservation Genetics (2014)

Knowledge about the ecology of bottlenose dolphins in the Southwestern Atlantic Ocean is scarce. Increased by-catch rates over the last decade in coastal waters of southern Brazil have raised concerns ... [more ▼]

Knowledge about the ecology of bottlenose dolphins in the Southwestern Atlantic Ocean is scarce. Increased by-catch rates over the last decade in coastal waters of southern Brazil have raised concerns about the decline in abundance of local dolphin communities. Lack of relevant data, including information on population structure and connectivity, have hampered an assessment of the conservation status of bottlenose dolphin communities in this region. Here we combined analyses of 16 microsatellite loci and mitochondrial DNA (mtDNA) control region sequences to investigate genetic diversity, structure and connectivity in 124 biopsy samples collected over six communities of photographically identified coastal bottlenose dolphins in southern Brazil, Uruguay and central Argentina. Levels of nuclear genetic diversity were remarkably low (mean values of allelic diversity and heterozygosity across all loci were 3.6 and 0.21, respectively), a result that possibly reflects the small size of local dolphin communities. On a broad geographical scale, strong and significant genetic differentiation was found between bottlenose dolphins from southern Brazil-Uruguay (SB-U) and Baia San Antonio (BSA), Argentina (AMOVA mtDNA ΦST = 0.43; nuclear FST = 0.46), with negligible contemporary gene flow detected based on Bayesian estimates. On a finer scale, moderate but significant differentiation (AMOVA mtDNA ΦST = 0.29; nuclear FST = 0.13) and asymmetric gene flow was detected between five neighbouring communities in SB-U. Based on the results we propose that BSA and SB-U represent two distinct Evolutionarily Significant Units (ESUs), and that communities from SB-U comprise five distinct Management Units (MUs). Under this scenario, conservation efforts should prioritize the areas in Southern Brazil where dolphins from three MUs overlap in their home ranges and where by-catch rates are reportedly higher. [less ▲]

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See detailStudy of the geometrical inaccuracy on a SPIF two-slope pyramid by finite element simulations
Guzmán Inostroza, Carlos Felipe ULg; Gu, Jun; Duflou, Joost et al

in International Journal of Solids and Structures (2012), 49(25), 3594-3604

Single Point Incremental Forming (SPIF) is a recent manufacturing process which can give a symmetrical or asymmetrical shape to an undeformed metal sheet by using a relative small tool. In this article, a ... [more ▼]

Single Point Incremental Forming (SPIF) is a recent manufacturing process which can give a symmetrical or asymmetrical shape to an undeformed metal sheet by using a relative small tool. In this article, a two-slope SPIF pyramid with two different depths, which suffers from large geometric deviations when comparing the intended and final shapes, is studied. The article goal is to detect if these divergences are due to new plastic strain while forming the second angle pyramid by using finite elements simulations. To validate the numerical results, both the shape and the forces are compared with experimental measurements. Then, an analysis of the material state is carried out taking the equivalent plastic strain, von Mises effective stress and yield stress distribution through a cut in the mesh. It is noticed that there is plastic deformation in the center of the pyramid, far from the tool neighbourhood. Also, high values of stresses are observed under the yield stress in other parts of the sheet. As a strong bending behaviour plus membrane tension is found in some sheet elements, these elastic stresses are due to a bending action of the tool. It is concluded that the main shape deviations come from elastic strains due to structural elastic bending, plus a minor contribution of localized springback, as no plastic deformation is observed in the angle change zone. Future developments in toolpath designs should eventually consider these elastic strains in order to achieve the intended geometry. [less ▲]

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See detailInfluence of the addition of functionalized MWCNT on mechanical properties on epoxy/carbon fiber and epoxy/carbon-aramid fiber composites
Fernandez, Carolina; Flores, Paulo; Montrieux, Henri-Michel ULg et al

in Proceedings of the 1st Brazilian Conference on Composite Materials (2012, July)

We investigated the effect of the inclusion of carbon nanotubes (CNT) on the mechanical properties and wear behavior of epoxy/carbon and epoxy/carbon-aramid composites in this study. Epoxy/carbon and ... [more ▼]

We investigated the effect of the inclusion of carbon nanotubes (CNT) on the mechanical properties and wear behavior of epoxy/carbon and epoxy/carbon-aramid composites in this study. Epoxy/carbon and epoxy/carbon-aramid composites with 0 wt.% CNT and 0.3 wt.% CNT were manufactured by RTM, amino functionalized multi-walled CNT (MWCNT) were used to modify the matrix. Tensile, compression, two rail shear, Charpy impact tests and Pin On Disc (POD) were performed on the four composites. The EP/CAF composites showed better impact resistance than the ones containing carbon woven. The addition of CNTs improves the shear modulus in 5% for EP/CF composites and 6% for EP/CAF. The results also show that the dynamic friction coefficient is independent of the CNT content, and the specific wear rate shows no improvement with the selected test parameters. [less ▲]

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See detailRotation of axes for anisotropic metal in FEM simulations
Duchene, Laurent ULg; Lelotte, Thomas; Flores, Paulo et al

in International Journal of Plasticity (2008), (24), 397427

For the FE simulations relying on elasto-plastic models based on anisotropic yield locus description, it is important for the simulation accuracy to follow a Cartesian reference frame, where the yield ... [more ▼]

For the FE simulations relying on elasto-plastic models based on anisotropic yield locus description, it is important for the simulation accuracy to follow a Cartesian reference frame, where the yield locus is expressed. The classical formulations like the Hill 1948 model keep a constant shape of the yield locus when other texture based yield loci regularly update their shape. However in all these cases, the rotation of the Cartesian reference frame must be known. For simple shear tests performed on steel sheets, experimental displacements provide the actual updated position of initial orthogonal grids. The initial and final texture measurements give information on the average crystals rotation. For Hill constitutive law and texture based models, this paper compares the experimental results with different ways to follow the Cartesian reference frame: the co-rotational method, an original method based on the constant symmetric local velocity gradient and the Mandel spin computed by four different methods. [less ▲]

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See detailStudy of axes rotation during simple shear tests on aluminium sheets
Duchene, Laurent ULg; Diouf, B.; Lelotte, T. et al

in César de Sa, J. M. A.; Santos, Abel D. (Eds.) Proceedings of the 9th International Conference NUMIFORM 2007 (2007)

In order to model accurately the anisotropic material behavior during finite element simulations, a precise description of the material yield locus is required. Beside the shape (linked to the material ... [more ▼]

In order to model accurately the anisotropic material behavior during finite element simulations, a precise description of the material yield locus is required. Beside the shape (linked to the material model used), the size (related to the isotropic hardening) and the position (kinematic hardening) of the yield locus, its orientation is of particular interest when large rotations of the material are encountered during the simulations. This paper proposes three distinct methods for the determination of the material yield locus rotation: a method based on the Constant Symmetric Local Velocity Gradient (CSLVG), a corotational method and a method based on the Mandel spin. These methods are compared during simple shear tests of an aluminum sheet. [less ▲]

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See detailPlane strain test for metal sheet characterization
Flores, Paulo; Bonnet, Félix; Habraken, Anne ULg

in Key Engineering Materials [=KEM] (2007), 344

This article shows the influence of a plane strain test specimen geometry on the measurable strain field and the influence of free edge effects over the stress computation. The experimental strain field ... [more ▼]

This article shows the influence of a plane strain test specimen geometry on the measurable strain field and the influence of free edge effects over the stress computation. The experimental strain field distribution is measured over the whole deformable zone of a plane strain test specimen by an optical strain gauge. The chosen material is the DC06 IF steel of 0.8 mm thickness. The stress field is computed for several geometries at different strain levels by a Finite Element (FE) commercial code (Samcef ®). The results show that the stress field is sensitive to the specimen’s geometry and also to the tested material (strain field behavior is independent of material) and, based on results, an optimal specimen geometry is proposed in order to minimized the stress computation error. [less ▲]

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See detailModel Identification and FE Simulations Effect of Different Yield Loci and Hardening Laws in Sheet Forming
Flores, Paulo; Duchene, Laurent ULg; Bouffioux, Chantal ULg et al

in International Journal of Plasticity (2007), 23(3), 420-449

The bi-axial experimental equipment [Flores, P., Rondia, E., Habraken, A.M., 2005a. Development of an experimental equipment for the identification of constitutive laws (Special Issue). International ... [more ▼]

The bi-axial experimental equipment [Flores, P., Rondia, E., Habraken, A.M., 2005a. Development of an experimental equipment for the identification of constitutive laws (Special Issue). International Journal of Forming Processes] developed by Flores enables to perform Bauschinger shear tests and successive or simultaneous simple shear tests and plane strain tests. Flores investigates the material behavior with the help of classical tensile tests and the ones performed in his bi-axial machine in order to identify the yield locus and the hardening model. With tests performed on one steel grade, the methods applied to identify classical yield surfaces such as [Hill, R., 1948. A theory of the yielding and plastic flow of anisotropic materials. Proceedings of the Royal Society of London A 193, 281–297; Hosford, W.F., 1979. On yield loci of anisotropic cubic metals. In: Proceedings of the 7th North American Metalworking Conf. (NMRC), SME, Dearborn, MI, pp. 191–197] ones as well as isotropic Swift type hardening, kinematic Armstrong–Frederick or Teodosiu and Hu hardening models are explained. Comparison with the Taylor–Bishop–Hill yield locus is also provided. The effect of both yield locus and hardening model choices is presented for two applications: plane strain tensile test and Single Point Incremental Forming (SPIF). [less ▲]

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See detailSpringback and Twist Prediction of Roll Formed Parts
Bui, Quoc Viet; Boman, Romain ULg; Papeleux, Luc ULg et al

in Santos, Abel D.; Barata da Rocha, A. (Eds.) Proceedings of the IDDRG 2006 International Deep Drawing Research Group, Drawing the things to come, Trends and Advances in Sheet Metal Forming (2006, June)

In the construction market, Roll Forming is the reference forming process. Numerous parts are achieved in such a way: purlins, steeldecks or suspended ceiling parts are examples of it. Roll Forming is ... [more ▼]

In the construction market, Roll Forming is the reference forming process. Numerous parts are achieved in such a way: purlins, steeldecks or suspended ceiling parts are examples of it. Roll Forming is also more and more used in the automotive industry, as it constitutes a good alternative to forming for High Strength Steels. Among the major requirements to obtain a defect-free product are outlined: the accurate geometry of the part, the taking into account of the springback as well as the prediction of twist. Furthermore, the roll forming operation could be only the first forming operation: the part could be curved or locally deep drawn afterwards. FE codes could allow fulfilling these requirements. However, they need significant advances in terms of material model description and numerical development. This paper presents the work done in order to predict the geometry and the behaviour of a roll formed part: First the material is characterized in complex strain paths in order to identify elaborated microstructural model like Teodosiu’s one. This model is able to take into account Bauschinger effect, orthogonal strain paths, isotropic/kinematic hardening. The METAFOR code is then used to have a better understanding of the mechanics of the deformation of the strip during the forming process. Several experimental campaigns were performed on the I-R&D ARCELOR roll forming machine to define a strong database in order to validate the numerical results. The geometry of machine as well as the shape of the channels inside and outside the RF machine were measured. Some experiments were even carried out in order to generate defects like twist in the roll formed profile. [less ▲]

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See detailCaracterizacion del comportamiento elasto-plastico de placas metalicas
Flores, Paulo; Habraken, Anne ULg

(2006)

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See detailAxes rotation during simple shear test: Measurement and predictions
Lelotte, Thomas; Gerday, Anne-Françoise ULg; Flores, Paulo et al

in Oñate, E.; Owen, D. R. J. (Eds.) Proceedings of the VIII International Conference on Computational Plasticity (COMPLAS VIII) (2005)

For a simple shear test, the finite element (FE) local frame, that stays orthogonal, does not follow the anisotropic material frame. To study this effect, FE simulations have been compared with ... [more ▼]

For a simple shear test, the finite element (FE) local frame, that stays orthogonal, does not follow the anisotropic material frame. To study this effect, FE simulations have been compared with experimental results (optical and texture measurements) and it was shown that it is necessary to take into account the effect of texture updating for local axes rotation. [less ▲]

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See detailMaterial Identification Using a Bi-Axial Test Machine
Flores, Paulo; Moureaux, Pierre; Habraken, Anne ULg

in Proceedings of the International Conference on Advances in Experimental Mechanics (2005)

This paper shows the identification of material parameters for a DC06 IF steel sheet of 0.8 mm by mechanical tests. The experimental equipment used consists of a tensile test machine, a bi-axial test ... [more ▼]

This paper shows the identification of material parameters for a DC06 IF steel sheet of 0.8 mm by mechanical tests. The experimental equipment used consists of a tensile test machine, a bi-axial test machine able to perform plane-strain and simple shear tests separately or simultaneously and an optical strain gauge. Tensile, plane-strain and simple shear tests were performed at 0°, 45° and 90° from the sheet rolling direction in order to identify Hill 1948 and Hosford 1979 yield criteria. Two identification methods are used: one based on strain measurements (anistropy coefficients) and the other one based on stress measurements (plastic contours). The results confirm that mechanical tests applying other stress-states than tensile are required to obtain accurate material parameters identification. [less ▲]

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See detailModel identification and FE simulations: effect of different yield loci and hardening laws in sheet forming
Flores, Paulo; Duchene, Laurent ULg; Lelotte, Thomas et al

in Smith, L. M.; Pourboghrat, F.; Yoon, J. W. (Eds.) et al On the Cutting Edge of Technology NUMISHEET 2005, Proceedings of the 6th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes (2005)

The bi-axial experimental equipment [1] developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and ... [more ▼]

The bi-axial experimental equipment [1] developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and classical tensile tests investigate the material behavior in order to identify the yield locus and the hardening models. With tests performed on two steel grades, the methods applied to identify classical yield surfaces such as Hill or Hosford ones as well as isotropic Swift type hardening or kinematic Armstrong–Frederick hardening models are explained. Comparison with the Taylor-Bishop-Hill yield locus is also provided. The effect of both yield locus and hardening model choice will be presented for two applications: Single Point Incremental Forming (SPIF) and a cup deep drawing. [less ▲]

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See detailDevelopment of an experimental equipment for the identification of constitutive laws
Flores, Paulo; Rondia, Etienne ULg; Habraken, Anne ULg

in International Journal of Forming Processes (2005), (Special Issue), 117-137

An experimental testing equipment for sheet samples is built in order to identify material parameters ofcomplex phenomenological constitutive laws. This equipment consists in a bi-axial test machine able ... [more ▼]

An experimental testing equipment for sheet samples is built in order to identify material parameters ofcomplex phenomenological constitutive laws. This equipment consists in a bi-axial test machine able to perform plane strain and simple shear tests separately or simultaneously and a Miyauchi simple shear test device. An optical extensometer is used to identify the strain field. The article is focused on the validation of the results of this new equipment by comparing with results obtained by finite elements (FE) simulations of already identified materials. The results are satisfactory and the bases for further material identification are established. [less ▲]

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See detailIdentification of material parameters using bi-axial machine
Flores, Paulo; de Montleau, P.; Mathonet, V. et al

in Stören, Sigurd (Ed.) Proceedings of the 7th ESAFORM conference on Materials Forming (2004)

Experimental testing equipment is built in order to identify material parameters of complex phenomenological constitutive laws. This equipment consists in a bi-axial test machine able to perform plane ... [more ▼]

Experimental testing equipment is built in order to identify material parameters of complex phenomenological constitutive laws. This equipment consists in a bi-axial test machine able to perform plane strain and simple shear tests separately or simultaneously and a Miyauchi simple shear test device; an optical extensometer is used to identify the strain field. The article focus on the validation of the results of this new equipment by comparing with results obtained by standard machines and/or by using FEM simulations of already identified materials. The first results show that the bi-axial machine performs the plane strain test optimally and some modifications are proposed in order to improve the results for the simple shear test. Miyauchi device shows a good performance and the experimental results are compared with a FEM simulation. [less ▲]

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See detailDeep drawing process with different elasto-plastic law
de Montleau, P.; Duchene, Laurent ULg; Bouvier, S. et al

in Stören, Sigurd (Ed.) Proceedings of the 7th ESAFORM conference on Material Forming (2004)

Recently, a combination of a texture based yield locus and of the Teodosiu's hardening model has been implemented in the Finite Element code LAGAMINE of the department M&S of the University of Liège. The ... [more ▼]

Recently, a combination of a texture based yield locus and of the Teodosiu's hardening model has been implemented in the Finite Element code LAGAMINE of the department M&S of the University of Liège. The yield locus is able to take into account the texture updating during a FE simulation. The texture evolves with respect to the crystalographic rotations due to the plastic deformations. Two hardening models are considered: the classical Swift istropic hardening model and the Teodosiu's hardening model that is a physically-based microstructural model. It takes into account intergranular heterogeneity due to the evolution of dislocation structures, that affects the isotropic and the kinematic hardening. The aim of the paper is to compare the influence of the hardening with the influence of the yield shape updating due to the texture evolution, on the final plastic anisotropy, for a deep drawing simulation. The tests are performed for the steel FeP06t that presents a non negligible initial anisotropy. [less ▲]

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See detailSimulations numériques d'essais de cisaillement simple
Flores, Paulo; De Montleau, P.; Habraken, Anne ULg et al

in 16ème Congrès fançais de Mécanique (2003)

Several tests have been designed in order to identify the initial yield locus and the parameters required in hardening laws. Taking into account the work done by Piljman (2001), M&S laboratory has started ... [more ▼]

Several tests have been designed in order to identify the initial yield locus and the parameters required in hardening laws. Taking into account the work done by Piljman (2001), M&S laboratory has started the construction of a bi-axial machien able to perform plane strain test, shear test (monotonic or cyclic), and a simultaneous combination of both. This article presents the simulation of a cyclic simple shear test using three types of hardening. [less ▲]

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See detailNumerical shear tests for different elasto-plastic laws
de Montleau, P.; Duchene, Laurent ULg; Flores, Paulo et al

in Onate, E.; Owen, D. R. J. (Eds.) Proceedings of the VII International Conference on Computational Plasticity (COMPLAS 2003) (2003)

This paper presents the numerical simulation of a cyclic simple shear test. The blank tested is a high strength steel sheet for which we use three different constitutive plastic laws derived from Teodosiu ... [more ▼]

This paper presents the numerical simulation of a cyclic simple shear test. The blank tested is a high strength steel sheet for which we use three different constitutive plastic laws derived from Teodosiu's model. These laws take into account respectively isotropic, kinematic and mixed isotropic-kinematic hardening. The goal of the paper is to provide a first numerical idea of the stress-strain path in the center of an experimental test sample. [less ▲]

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See detailTexture analysis of cylindrical cup during deep-drawing process
Flores, Paulo; Duchene, Laurent ULg; Habraken, Anne ULg

in Yang, D. Y.; Oh, S. I.; Huh, H. (Eds.) et al Proceedings of the 5th international conference NUMISHEET 2002 (2002)

This paper presents the simulation of a deep-drawing process using three different constitutive laws: strain rate space yield locus description with an isotropic hardening law, strain rate space yield ... [more ▼]

This paper presents the simulation of a deep-drawing process using three different constitutive laws: strain rate space yield locus description with an isotropic hardening law, strain rate space yield locus description with a combined (isotropic and kinematic) hardening law, and stress space yield locus description with an isotropic hardening law. To take into consideration material anisotropy, the yield locus is computed from the crystallographic texture using Taylor's model, a dual plastic potantial and combined hardening law taking into account the dislocations microstructures. The results obtained by these three constitutive laws are compared with experimental ones. [less ▲]

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