Department of Physics, Engineering Physics & Astronomy

Queen's University
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Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

SNOLAB Talk - "Monitoring of acoustic emission and light during fracture"

Prof. S. Deschanel
INSA, Lyon

Monday March 2nd 2015
12:30, Stirling 261


In our every-day life, many structures are subjected to a permanent subcritical stress. As stresses intensify around a flaw in the material, a micro-crack can eventually start growing, until it reaches a critical length where the whole system fails. This process, called subcritical fracture, has captured the attention of scientists and engineers for more than half a century. The lifetime of a material subject to a subcritical stress depends not only on the applied stress but also generally on temperature.

Subcritical fracture of heterogeneous materials is usually studied by two different experimental approaches: acoustic emission (AE) or direct imaging (DI).  Prompted by intriguing events observed in certain particle-physics searches for rare events, we study some inorganic scintillators subject to mechanical stress by combining AE and DI with a measurement of light. We study the inorganic scintillator Bi4Ge3O12 providing evidence that light is emitted during material damage at room temperature and pressure. By using the double cleavage drilled compression geometry, we show that light and acoustic emission are correlated. To further understand the origin of these phenomena, we are commissioning a vacuum chamber to observe the influence of the pressure on the crack propagation and on the light emitted during material damage. One of the challenges will also be to predict the lifetime of the material depending on the applied stress and temperature; the influence of the environment (humidity, pressure…) being another parameter involved in the rupture process.