Mécanismes et tenue mécanique long-terme de mousses polyuréthanes pures et renforcées aux températures cryogéniques

Abstract : The general framework of the study concerns the long term creep resistance of polyurethane foams used in the wall of LNG tanks. The mechanical behavior in monotonic compression, low stress creep and dynamic mechanical analysis (DMA) has been characterized at cryogenic temperatures (-170°C) for polyurethane foam reinforced or not by the glass fiber mat. The first objective was to characterize the response and the mechanisms activated at low temperatures. The induced damage by the strong cooling of samples affects the earliest stages of deformation in compression, depending on the sample size. The micrographs and tomographic observations post-mortem did not show obvious damage. A creep recovery deformation is also observed. The second objective was to consider a prediction method for long-term creep by time-temperature equivalence in DMA. The various transitions observed between -170°VC and glass transition have been analyzed, as well as the representativeness of small samples used in this device. The results obtained in multifrequency DMA have not allowed the construction of mater curve. This approach is not the most appropriate to predict the creep behavior under low stress and long term of these foams.
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Submitted on : Tuesday, October 9, 2012 - 2:10:20 PM
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Anne-Gaëlle Denay. Mécanismes et tenue mécanique long-terme de mousses polyuréthanes pures et renforcées aux températures cryogéniques. Matériaux. ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers, 2012. Français. ⟨NNT : 2012ESMA0004⟩. ⟨tel-00740110⟩

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