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Colmar Berg, Luxembourg

Rauchs G.,CRP Henri Tudor | Bardon J.,CRP Henri Tudor | Georges D.,Goodyear Innovation Center Luxembourg
Mechanics of Materials | Year: 2010

In this article, the material parameters of different rubber compounds are determined by an inverse method based on gradient-based numerical optimization, using experimental data from depth-sensing spherical indentation testing. The deformation behaviour of rubber is described by the Zener model. The indentation test is modeled by a finite strain finite element model, and the gradients necessary for the inverse method are determined by direct differentiation. Four different rubber compounds are analyzed, and the material parameters obtained from spherical indentation testing are used to model a uniaxial tensile test, for comparison with experimental data. © 2010 Elsevier Ltd. All rights reserved.

Mzabi S.,ESPCI ParisTech | Berghezan D.,Michelin | Roux S.,Ecole Normale Superieure de Cachan | Hild F.,Ecole Normale Superieure de Cachan | And 2 more authors.
Journal of Polymer Science, Part B: Polymer Physics | Year: 2011

Using Digital Image Correlation on high-resolution images, the full strain field near the tip of a crack propagating under cyclic loading in an elastomer was characterized. We show unambiguously, and for the first time, the existence of a strongly localized and highly oriented process zone close to the crack tip and propose a simple physical model introducing a local energy release rate glocal = WunloadingH0, where W unloading is the unloading strain energy density in uniaxial tension at the maximum strain measured at the crack tip, and H0 is the undeformed size of the highly stretched zone in the loading direction. Remarkably, the crack growth rate under cyclic loading is found to fall on a master curve as a function of glocal for three elastomers with different filler contents and crosslinking densities, while the same crack growth rate as a function of the applied macroscopic energy release rate G, differs by two orders of magnitude for the same three elastomers. © 2011 Wiley Periodicals, Inc.

Vercammen S.,Goodyear Innovation Center Luxembourg | Bianciardi F.,Siemens AG | Kindt P.,Goodyear Innovation Center Luxembourg | Desmet W.,Catholic University of Leuven | Sas P.,Catholic University of Leuven
SAE Technical Papers | Year: 2015

In the context of the reduction of traffic-related noise the research reported in this paper provides tools that could be used to develop low noise tyres. Two measurement techniques have been analyzed for exterior noise radiation characterization of a loaded rotating slick tyre on a rough road surface. On one hand sound pressure measurements at low spatial resolution with strategically placed microphones on a half-hemisphere around the tyre/road contact point have been performed. This technique provides a robust solution to compute the (overall) sound power level. On the other hand sound intensity measurements at high spatial resolution by means of a scanning intensity probe have been performed. This technique allows a more detailed spatial visualization of the noise radiation and helps in getting more insight and better understanding of the acoustical phenomena. Copyright © 2015 SAE International.

Schwartz G.A.,Donostia International Physics Center | Colmenero J.,University of the Basque Country | Colmenero J.,Donostia International Physics Center | Loichen J.,Goodyear Innovation Center Luxembourg | Westermann S.,Goodyear Innovation Center Luxembourg
Journal of Physical Chemistry C | Year: 2012

The effect of water content on silica nanoparticles was examined by thermogravimetry analysis (TGA), broadband dielectric spectroscopy (from 10 -2 to 107 Hz), and differential scanning calorimetry for a wide temperature range (110-250 K). Silica nanoparticles were dried and rehydrated at different water levels to determine the critical factors affecting the dielectric response. The dynamics of both hydration water and hydrated silanol groups were addressed. Whereas hydration water dynamics depend on the water content, the dynamics corresponding to hydrated silanol groups are almost water independent once the maximum hydroxylation level is reached. In addition, we determined that during hydration water molecules prefer to form clusters instead of filling a complete layer around the particles. Finally, we observed that contrary to other water containing systems, the corresponding relaxation times of water molecules do not show any crossover (from high-T super-Arrhenius to low-T Arrhenius behavior). © 2012 American Chemical Society.

Hermann A.,University of Mainz | Mruk R.,Goodyear Innovation Center Luxembourg | Roskamp R.F.,Goodyear Innovation Center Luxembourg | Scherer M.,University of Mainz | And 2 more authors.
Macromolecular Chemistry and Physics | Year: 2014

Narrowly distributed ( N -isopropylacrylamide) (NIPAM) polymers are prepared by reversible addition- fragmentation chain transfer (RAFT) polymerization. After successful cleavage of the trithiocarbonate end groups (thiol generation), they can be grafted to styrene-butadiene rubber (SBR) by a radical thiol-ene reaction leading to various grafted SBR-copolymers. During the grafting reaction, no crosslinking or branching of the SBR can be observed. Measurements of the contact angle of water show that the lower critical solution temperature (LCST) properties of the PNIPAM fraction affect the SBR. Films of the graft-copolymer exhibit a distinct hydrophilicity below the LCST, while they show hydrophobic behavior above the LCST. Rheological measurements reveal a physical crosslinking of the functionalized SBR due to nanophase separation of the PNIPAM chains (hard phase) in the unpolar SBR. Compared with blends of SBR and PNIPAM, the PNIPAMgrafted SBR possesses a much finer distribution of the PNIPAM domains (10-30 nm) within the matrix. In addition, two novel difunctional chaintransfer agents are used, leading to difunctional PNIPAM, enabling a covalent crosslinking of SBR. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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