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SUMMARY:The quasi-stationary nature of ‘steady-state’ cyclic deformati
 on - Hael Mughrabi\, Friedrich-Alexander University of Erlangen-Nürnberg\
 ,  Germany
DTSTART:20180208T160000Z
DTEND:20180208T170000Z
UID:TALK96919@talks.cam.ac.uk
CONTACT:Stephen Walley
DESCRIPTION:The cyclic stress-strain (CSS) behaviour of fatigued metals is
  fundamental to formulations of fatigue life prediction. The CSS curve of 
 so-called wavy slip materials is considered to be unique and history-indep
 endent.  In ‘mechanical’ cyclic saturation in the sense that the loadi
 ng parameters (stress and strain) remain constant\, it is generally assume
 d that so-called ‘steady-state’ conditions prevail. Accordingly\, the 
 deformation-induced dislocation microstructure is assumed to attain a cons
 tant state\, resulting from a dynamic equilibrium between defect productio
 n and annihilation.\nHere\, it will be shown\, based on earlier experiment
 al studies\, including microstructural observations and measurements of di
 fferent defect-sensitive physical properties\, that mild but non-negligibl
 e changes of the microstructure persist well into ‘mechanical’ saturat
 ion. It follows that a distinction must be made between ‘mechanical’ a
 nd ‘microstructural’ saturation and that so-called ‘steady-state’ 
 cyclic deformation is actually only quasi-stationary.\nThe consequences of
  this behaviour will be discussed.\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory
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