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DTSTART:19700329T010000
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CATEGORIES:Engineering - Mechanics and Materials Seminar Seri
 es
SUMMARY:Strain gradient plasticity: Numerical modeling of 
 size-effects in porous metals - Prof Christian F. 
 Niordson\, DTU
DTSTART;TZID=Europe/London:20190524T140000
DTEND;TZID=Europe/London:20190524T150000
UID:TALK119800AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/119800
DESCRIPTION:Micron scale size-effects in metals have been conf
 irmed in numerous experiments\, exhibiting the gen
 eral trend that smaller is stronger. For torsion o
 f micron scale wires and bending of thin films\, i
 t has been found that normalized twisting and bend
 ing resistance in the plastic deformation range in
 crease with decreasing specimen size. In micro- an
 d nano-indentation testing increased hardness for 
 smaller indentations are measured. It is generally
  accepted these size-effects in metals are due to 
 so-called geometrically necessary dislocations tha
 t arise in the presence of very large plastic stra
 in gradients. Such gradients may be imposed due to
  inhomogeneous overall deformation as in the examp
 les above\, but they can also arise under homogene
 ous deformation when boundaries are passivated\, s
 uch that plastic deformation is hindered due to bl
 ockage of dislocations.\n\nThe first part of this 
 presentation presents a basis for numerical modeli
 ng of strain gradient plasticity\, both in the con
 text visco-plastic materials and time-independent 
 plasticity.\n\nThe second part treats size-effects
  in void growth\, with emphasis on extensions of c
 onventional porous metal yield surfaces to include
  micron scale size-effects. \n
LOCATION:Oatley Seminar Room\, Department of Engineering
CONTACT:Hilde Hambro
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