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SUMMARY:Crackling noise of crumbling minerals - Ekhard Salje (Department o
 f Earth Sciences)
DTSTART:20101018T150000Z
DTEND:20101018T160000Z
UID:TALK26581@talks.cam.ac.uk
CONTACT:Ian Farnan
DESCRIPTION:The criteria of elastic instabilities of solids are understood
  for 50 years\, the physical nature of the elastic collapse for 20 years. 
 We just start to understand the dynamics of such instabilities\, in partic
 ular in first order transitions. I will show that continuous front propaga
 tion (solitons) is virtually always superimposed by jerks and avalanches w
 hich give rise to 'crackling noise'. Continuous measurements in DSC and RU
 S ignore this contribution while acoustic emission measurements are blind 
 towards the continuous front propagation. I will show that even defect fre
 e ferroelastic crystals show crackling noise because jamming by twin bound
 aries leads to avalanche type progression of transformation fronts. Elasti
 c softening is also observed in metamict minerals such as titanite where d
 ynamic softening overcompensates static hardening.
LOCATION:Harker 2 lecture room\, Department of Earth Sciences\, Downing Si
 te
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