BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Studies of plastic flow localization in different materials - Prof
 essor V Tvergaard\, Department of Mechanical Engineering\, Solid Mechanics
 \, Technical University of Denmark
DTSTART:20081015T130000Z
DTEND:20081015T140000Z
UID:TALK13660@talks.cam.ac.uk
CONTACT:Ms Helen Gardner
DESCRIPTION:Part of the lecture will focus on the behaviour of polymer tub
 es under growing internal pressure. The polymer is characterized by a fini
 te strain elastic-viscoplastic constitutive relation and the calculations 
 are carried out using a dynamic finite element programme. During the tube 
 expansion the onset of necking and subsequent neck propagation is studied.
  First the idealised assumption of plane strain conditions is considered. 
 Subsequently\, the behaviour of a long thin pressurized tube is analyzed\,
  where bulge formation interacts with the necking. Two types of imposed lo
 ading are prescribed\, either a pressure that increases linearly with time
 \, or an enclosed volume that increases linearly with time. The necks prop
 agate in both the circumferential and the axial directions.\n\n\nAnother p
 art of the lecture will consider the behaviour of voids in a ductile metal
  subject to pure shear or to a shear dominated stress state. Here the stre
 ss triaxiality is so low that instead of void volume growth to coalescence
  there is void closure leading to micro- cracks that rotate in the shear f
 ield. At some stage of the deformation the void surfaces will come in cont
 act so that sliding with or without friction will start to occur. If a max
 imum overall shear stress is reached\, localization of plastic flow will o
 ccur\, leading to final failure of the material. In the micromechanical mo
 del to be presented\, an internal pressure is used to approximately repres
 ent void surfaces pressed together in frictionless sliding.
LOCATION:CUED LR4
END:VEVENT
END:VCALENDAR