کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10121399 | 1641622 | 2005 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Frequency dependence of elastic wave speeds at high temperature: a direct experimental demonstration
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فیزیک زمین (ژئو فیزیک)
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چکیده انگلیسی
At sufficiently high temperatures and/or long periods, the elastic behaviour of crystalline material gives way progressively to viscoelastic behaviour associated with the stress-induced migration of crystal defects. This transition is marked by the onset of appreciable strain energy dissipation accompanied by frequency dependence (dispersion) of the shear modulus and elastic wave speeds. Ultrasonic interferometry and torsional forced-oscillation techniques can be used to probe the low-amplitude stress-strain behaviour of fine-grained polycrystalline material in two very different frequency ranges, respectively 10-100 MHz and 1 mHz-1 Hz. Here we demonstrate and apply these two complementary methods in a study of the high-temperature mechanical behaviour of a fine-grained synthetic olivine polycrystal. At the high frequencies of ultrasonic interferometry, the shear wave speed varies linearly with temperature between room temperature and the highest experimentally accessible temperature (1300 °C) in close accord with expectations based on similarly high-frequency studies of the elastic behaviour of single-crystal olivine. However, at teleseismic frequencies (<1 Hz) and temperatures >900 °C, the shear wave speed becomes much more strongly temperature-sensitive reflecting markedly viscoelastic behaviour. Newly emerging laboratory-derived constraints on this viscoelastic enhancement of the temperature sensitivity of seismic wave speeds and its grain-size dependence will provide a more robust interpretation of seismological models for the variation of wave speeds and attenuation within the Earth's interior.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physics of the Earth and Planetary Interiors - Volume 148, Issue 1, January 2005, Pages 85-96
Journal: Physics of the Earth and Planetary Interiors - Volume 148, Issue 1, January 2005, Pages 85-96
نویسندگان
Ian Jackson, Sharon Webb, Lara Weston, David Boness,