Polarization-depolarization process in glass during percussion drilling |
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Authors: | A Rabinovitch V Frid J Goldbaum D Bahat |
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Institution: | 1. The Deichmann Rock Mechanics Laboratory of the Negev, Physics Department , Ben Gurion University of the Negev , Beer Sheva, Israel;2. The Deichmann Rock Mechanics Laboratory of the Negev, Geological and Environmental Science Department , Ben Gurion University of the Negev , Beer Sheva, Israel |
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Abstract: | In addition to short individual high-frequency signals and their strings, which are well known and analysed, electromagnetic radiation measured during percussion drilling of glass showed a group of lengthy pulses usually appearing in pairs (denoted a-b). In order to understand their origin a polarization-depolarization process is invoked. Thus it is assumed that, during drilling, stress is accumulated in the sample, its increase being accompanied by a polarization increase, which is undetected by the equipment. When stress reaches a critical value, large crack propagation ('chip' fragmentation) begins, and a group a signal is emitted. Crack propagation causes stress and polarization relaxation, and the latter is detected as a group b signal. |
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