publications

WCPSE 2018

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Degradation mechanism of glass fiber-reinforced polyphenylene sulfide (PPS) under long-time aging

P. Zuo1*, B. Esmaeillou2, M. Shirinbayan1, R.C. Benevides3, J. Fitoussi1, F. Bakir2, A. Tcharkhtchi1
1 Arts et Métiers ParisTech, PIMM - UMR CNRS 8006, 151 Boulevard de l'Hôpital, 75013 Paris, France:
2 Arts et Métiers ParisTech, Dyfluid - UMR CNRS 8006, 151 Boulevard de l'Hôpital, 75013 Paris, France:
3 Valeo thermique habitacle, Valeo powertrain thermal systems, 8 Rue Louis Lormand, 78321 La varrière, France




In this paper, the effect of aging on PPS composite materials under different thermal conditions was studied and then a wide range of aspects were tested. The temperatures of aging were chosen by 100 °C, 180 °C and 200 °C respectively. Also, aging time was up to about 3900 hours. The main results are as follows: for the temperatures below 200 °C, the weight loss ratio was very small (below 1%) until approximately 3600 hours. On the other hand, for all samples aged at 200 °C, they all had high storage modulus than virgin samples, during all range of testing temperature, and the tan δ declined with the increasing of aging time. This trend became really progressive with the aging temperature increasing. The degree of crosslinking became more and more serious with the aging time and temperature increasing and the Tg value was sensitive to the aging time and temperature. At the same time, the ∆E energy for virgin sample was 990 J/mol, for the sample aged at 100 °C after 240 h, the value of ∆E energy declined slightly. In other cases, all of ∆E energy values enhanced. In aspect of mechanical properties, the σmax dropped with the oxidation time increasing. Also with the thermal oxidation temperature increasing, the dropping trend became more visible and progressive. Also, the interface between fiber and matrix was observed for unaged and aged samples. In the end, the possible schematic diagram for degradation of PPS composites was confirmed.

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ASME 2018

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LARGE EDDY SIMULATIONS OF A HIGHLY LOADED TRANSONIC BLADE
WITH SEPARATED FLOW





Pour respecter les nouvelles réglementations environnementales et réduire la consommation de carburant en aéronautique, l'efficacité du moteur doit être considérablement améliorée. Les conceptions de pales de turbines récentes conduisent à des pales de pression fortement chargées pour optimiser la taille et le coût La forte déviation du flux dans de tels cas peut conduire à un gradient de pression inverse élevé et produire une séparation de l'écoulement. Si une séparation se produit, les recherches indiquent que la taille de la bulle est déterminée par l'état de la couche limite située en amontL'article montre l'effet de l'injection turbulente d'entrée sur la structure d'écoulement et sur le point de fonctionnement d'une lame haute pression avec séparation. Il aborde aussi la question sur la quantification des pertes en raison de son importance dans la conception technique.



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PERMAS 2018

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AIR INTAKE MODULE (AIM) OPTIMISATION
FROM MULTIPHYCAL ANALYSES




The Air Intake Module (AIM) is an automotive water-cooled air inlet module aimed to improve the engine efficiency. This innovative and effective solution for turbocharged engines helps engine downsizing and allows meeting new regulation for reduced fuel consumption and pollutant production. This newest product in the automotive market is used as a test case in the Cascade project in which manufacturers such as CEA, Safran Helicopter Engines and Valeo join their forces to develop fast and efficient processes for multiphysics simulations and optimization.
Multiphysical simulations are conducted to simulate the real behavior of the AIM. The difficulty of such a study is the large size of the F.E. model and the presence of two distinct fluids in contact with a solid part. A unique complex model has been built and all the dimensioning loads are taken into account (temperature, cycled pressure and vibration), aiming to evaluate robustness, fatigue or damage.
On a second time, using a submodelling method, the behaviour of critical areas of the system submitted to working cycles has been simulated, u A reliability analysis has also been computed to estimate the probability of failure, taking into account the building process imprecisions.

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Essais & Simulations


cascade
Un projet de recherche
pour la co-conception de produits industriels



Comment utiliser et intégrer efficacement les outils de simulation dans l’environnement de conception des bureaux d’étude, dès les premières ébauches et tout au long des études, gérer leurs interactions mutuelles en terme programmatique mais également dans les processus d’ingénierie?

ES-Logo-HD-JPG

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ASME 2017


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SENSITIVITY OF LARGE EDDY SIMULATIONS TO INFLOW CONDITION AND MODELING
IF APPLIED TO A TRANSONIC HIGH-PRESSURE CASCADE VANE




Large Eddy Simulation (LES) prediction of the flow around transonic high-pressure turbine cascade vanes is an active sub- ject of research. For such problems, the flow topology is dictated by the geometry, inflow conditions and irreversibilities. When studied experimentally, input specifications necessarily suffer from uncertainties inherent to experimental measurement facil- ities. Such limits are also present in numerical applications. The following paper proposes to evaluate the relative importance of uncertainty sources in determining the adequate LES flow behav- ior for the T120 transonic blade experimentally tested at UniBw (Munich) during the European project AITEB II. To do so, the nominal operating point is targeted and different simulations are obtained by changing inflow specifications with and without tur- bulence injection. As expected, changes in the inlet total pres- sure by more or less 4%, alter significantly the flow topology and shock position. Impact of turbulence injection at inlet is also addressed. Investigation of dissipation fields, including the lam- inar and sub-grid model contributions, allows the identification of the underlying mechanisms. Conclusions are that: although irreversibilities have a smaller impact on the operating condi- tion specification (relative to inlet total pressure values and un- certainties), its relevance on the flow prediction and topology is found to be of primary importance.

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SIA 2017

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Air Intake Module optimization from multiphysical numerical analysis -



The air intake module is innovative for charged air cooler component by not only reducing fuel consumption, but also pollutant emissions (NOx, CO2) while increasing driving comfort.
It is possible by designing a complex component, integrating many functions: EGR rail, air intake manifold, water cooling, swirl module.
All those complex aspects are all subjects to be treated in a unique numerical simulation model with : multiphysics (CFD, structural), coupling physics between themselves, loads variability with vibration, thermal shock, cycled pressure (air & coolant), integrating very thin and thick parts, and finally a large numerical model.

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WCPSE 2017

polymerscienceeurope2017-53592
8-9 mai. BARCELONE

Degradation mechanism of glass fiber-reinforced polyphenylene sulfide (PPS) under long-time aging




In this paper, the effect of aging on PPS composite materials under different thermal conditions was studied and then a wide range of aspects were tested. The temperatures of aging were chosen by 100 °C, 180 °C and 200 °C respectively. Also, aging time was up to about 3900 hours. The main results are as follows: for the temperatures below 200 °C, the weight loss ratio was very small (below 1%) until approximately 3600 hours. On the other hand, for all samples aged at 200 °C, they all had high storage modulus than virgin samples, during all range of testing temperature, and the tan δ declined with the increasing of aging time. This trend became really progressive with the aging temperature increasing. The degree of crosslinking became more and more serious with the aging time and temperature increasing and the Tg value was sensitive to the aging time and temperature. At the same time, the ∆E energy for virgin sample was 990 J/mol, for the sample aged at 100 °C after 240 h, the value of ∆E energy declined slightly. In other cases, all of ∆E energy values enhanced. In aspect of mechanical properties, the σmax dropped with the oxidation time increasing. Also with the thermal oxidation temperature increasing, the dropping trend became more visible and progressive. Also, the interface between fiber and matrix was observed for unaged and aged samples. In the end, the possible schematic diagram for degradation of PPS composites was confirmed.


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TMS 2017

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Influence of stress triaxiality and relaxation on the creep behavior
under oxidizing conditions of the nickel-based single-crystal superalloy CMSX-4:
experiments and numerical approach




In this work, the temperature, stress level and triaxiality dependence of the coupled creep/oxidation response of the nickel-based single-crystal superalloy CMSX-4, is investigated. In particular, the impact of stress relaxation close to notches, affecting local triaxiality, is studied through creep tests in air at very high temperatures (T > 1100°C) on specimens specifically designed to trigger this phenomenon.γ/γ’ microstructural evolutions of the material, observed after these tests, is analyzed through SEM characterizations and quantified by image analysis in order to take them into account in the development of the model.


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SIA 2016

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Optimisation avancée d'un module d'entrée d'air
à partir de simulations multiphysiques




Dans le cadre du projet collaboratif "Cascade" ("Boucle de conception agile et temps réel") qui a pour objectif de rapprocher les acteurs de terrain de la simulation numérique dans une démarche d'ingénierie collaborative afin d'optimiser des systèmes complexes proposés par Valeo et Turbomeca, les principes fondamentaux servant de trame au projet sont résumés par le triptyque : Conception, Simulation, Optimisation. Les co-auteurs de ce document travaillent sur la partie du projet relative au module automobile d’entrée d’air refroidi par eau ou "Air Intake Module" (AIM) (proposé par VALEO), et plus particulièrement sur les études de couplage entre fluide et structure dans un contexte de choc thermique, préalablement à des études d'optimisation, de fatigue et de robustesse du système étudié.

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ECF 21

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A new approach to simulate interface damage in brittle matrix composites




Under mechanical loading, brittle matrix composites develop various damage processes which include cracking of matrix and fiber/matrix interface Cohesive zone models are widely used to model interface damage . The aim of this paper is to propose an alternate approach based on a damage model associated to a diffuse meshing method. In this study, the crack deflection at the interface fiber/matrix in a SiC/SiC microcomposite is simulated using CZM and the results are compared with those obtained from a new approach based on a damage model associated to a diffuse meshing method.
The simulation of a tensile test (in the fiber direction) on a brittle single fiber composite is performed by using the damage model and shows a good agreement with the reference one obtained from CZM. On this basis, it is shown that the damage model is able to reproduce complex phenomenon as periodic matrix crack deflections at the fiber/matrix interface.

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