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| Titel |
Viscoelastic silicone oils in analog modeling - a rheological benchmark |
| VerfasserIn |
Michael Rudolf, David Boutelier, Matthias Rosenau, Guido Schreurs, Onno Oncken  |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123890
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| Publikation (Nr.) |
 EGU/EGU2016-3220.pdf |
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| Zusammenfassung |
| Tectonic analog models frequently use silicone oils to simulate viscous flow in the lower crust
and mantle. Precise knowledge of the model rheology is required to ensure dynamic
similarity with the prototype. We assessed the rheological properties of various silicone oils
using rotational and oscillatory tests. Resulting viscosities are in the range of 2 - 3 ×104 Pa s
with a transition from Newtonian viscous to power-law, shear-thinning, around shear rates of
10−2 to 10−1 s−1. Maxwell relaxation times are in the range of 10−1 s. Comparing the
rheological properties of chemically similar silicone oils from different laboratories shows
that they differ from laboratory to laboratory. Furthermore, we characterized the temperature
dependency of viscosity and aging effects. The samples show a reduction in zero-shear
viscosity over time. This stabilizes at a certain value over several months. The dynamic
moduli decrease as well, but other viscoelastic constants, such as the Maxwell relaxation
time, are not affected by aging. We conclude that the aging is mainly controlled by the
storage conditions and that a silicone shows no further aging when it has equilibrated
with the ambient laboratory conditions. We consider all these differences as minor
compared to the much larger uncertainties for estimating the lithosphere rheology.
Nevertheless, it is important that the rheological properties of the experimental
materials are monitored during an experimental series that spans over several weeks to
months.
Additionally, the viscoelastic properties may be scaled using dimensionless parameters
(Deborah number) and show a dynamically similar change from Newtonian to power-law
flow, like the natural prototype. In consequence, the viscoelasticity of these silicone oils is
able to mimic the change in deformation mechanism from diffusion to dislocation
creep. |
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