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SUMMARY:Fracture of warm ice - Professor Jukka Tuhkuri\, Aalto University
DTSTART:20240206T130000Z
DTEND:20240206T140000Z
UID:TALK211258@talks.cam.ac.uk
CONTACT:Michael Thorne
DESCRIPTION:Understanding how ice fractures has fundamental importance in 
 arctic marine technology\, geophysics\, and climate studies. The fracture 
 processes of interest include fragmentation of sea ice against polar ships
  and offshore wind turbines\, failure of sea ice by ocean waves\, formatio
 n of large leads in sea ice\, and formation of crevasses in glaciers. The 
 importance of ice fracture research is enhanced by global warming\, which 
 is not only melting the ice\, but is both increasing the fragmentation and
  changing the mechanical properties of ice. Warm ice is different than col
 d ice.\n\nThe talk will introduce recent large scale laboratory experiment
 s on the deformation and fracture of warm (-0.5C) columnar freshwater ice.
  The largest test plate had dimensions of 19.5m x 36m and a scale range of
  1:39 was covered. Loading times from 2 seconds to 1000 seconds resulted i
 n both elastic and viscous behaviour. It was observed that the rate and sc
 ale effects of fracture were interrelated and that the viscoelastic compon
 ent of ice deformation was negligible. The results obtained include appare
 nt fracture toughness\, fracture energy\, and size of the fracture process
  zone at the crack tip. The results are useful in future modelling of ice 
 fracture.\n\nThe talk will also discuss the effects of the warming ice on 
 polar navigation. It appears that the forces on a ship hull\, when breakin
 g warm and weak ice\, may be just as high as the ice loads caused by cold 
 and strong ice. While the strengths of cold and warm ice are different\, t
 he resulting forces on a ship hull may be similar. This observation underl
 ines the importance of fracture processes over strength in ice research.
LOCATION:British Antarctic Survey\, Seminar Room 330b
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