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SUMMARY:Structure-property relationships for sea ice: Modeling and experim
 ental validation - David Cole (U.S. Army Research Laboratory)
DTSTART:20171106T133000Z
DTEND:20171106T143000Z
UID:TALK94513@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:This talk addresses the constitutive behavior of sea ice\, wit
 h a focus on the relationships between measurable physical properties and 
 the elastic\, anelastic and viscous components of strain. To accommodate a
 ttendees with a limited knowledge of sea ice\, the presentation includes a
  brief overview of the microstructure and flaw structure of naturally occu
 rring sea ice. Some attention is paid to the structure and mechanics of co
 lumnar and granular freshwater ice for completeness. The components of str
 ain are quantified in terms of crystallographic characteristics (primarily
  c-axis orientation)\, dislocation density for the inelastic components\, 
 and temperature. The mechanisms of anelastic strain (e.g.\, time-dependent
  but recoverable) are associated with basal dislocation glide and grain bo
 undary sliding. Viscous straining is quantified in terms of drag-controlle
 d dislocation glide on the basal planes. It is shown that dislocation dens
 ity exerts an overwhelming influence on the constitutive behavior of sea i
 ce both at the scale of laboratory   experiments (0.1 m) and in-situ exper
 iments ( &le\; 30 m).       Recent efforts to account for certain high tem
 perature effects and differences between in-situ vs. in-vitro constitutive
  behavior of sea ice are described and the associated modifications to the
  published constitutive model are discussed. An analysis of existing cycli
 c loading and creep experiments makes it possible to identify the physical
  basis for the apparent increase in activation energy of inelastic behavio
 r with proximity to the melting point. Additionally\, brine drainage from 
 specimens harvested for laboratory experiments is shown to cause a major d
 iscrepancy between the in-situ elastic response of warm sea ice vs. that f
 ound in laboratory experiments.&nbsp\;
LOCATION:Seminar Room 1\, Newton Institute
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