Correlation between Acoustic Emission and Mechanoluminescence of Rock Cores under Quasistatic Compression
Loading...
Authors
Miller, Rachel A.
Issue Date
2012
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
When a rigid solid undergoes mechanical deformation, locally accumulated strain energy
can be released through multiple avenues including acoustic emission (AE) and
light emission known as mechanoluminescence (ML). In AE, events within a stressed
rock such as defect movement, grain boundary shifting, and crack propagation create
pressure waves which can be detected at the rock surface. While AE is used
extensively for rock evaluation in geophysics, civil engineering, and mining, ML by
comparison has received little attention from the geoscience community. ML from
stressed and fracturing rock has been observed in mines, earthquakes, and the laboratory,
but the underlying mechanism behind ML is poorly understood. Possible
candidates include defect movement, creation of charged surfaces during fracturing
of piezoelectric grains, and triboluminescence. Observing whether a correlation exists
between ML and AE will help determine the source of ML. An apparatus for
AE and ML detection of rock cores under quasistatic compression was designed and
constructed. Using photomultiplier tubes and piezoelectric transducers, AE and ML
events were spatially and temporally observed and correlated. AE and ML in Berea
sandstone were measured, and, unexpectedly, the ML events were found to occur
approximately 40 ?s after the AE events.
Description
Citation
Publisher
License
In Copyright(All Rights Reserved)