BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Towards adaptive numerical integration of dynamical contact proble
 ms - Peter Deuflhard (Zuse Institute Berlin\, Free University\, Berlin and
  MATHEON)
DTSTART:20090507T140000Z
DTEND:20090507T150000Z
UID:TALK18144@talks.cam.ac.uk
CONTACT:6743
DESCRIPTION:The author and his research group in computational medicine ha
 ve come across\ndynamical contact problems in the context of a collaborati
 on in orthopaedic surgery.\nSpecial first attention has focussed on the mo
 tion of the patient-specific knee.\n\nAs it turned out\, the numerical int
 egration of time dependent contact problems has stayed\nunsatisfactory for
  decades. The classical Newmark method\, which is quite popular in the eng
 ineering world\,\nis a real ''perpetuum mobile'' in that in generates ener
 gy! A rather recent improvement due the\nCaltech group around Marsden and 
 Ortiz is energy dissipative\, but still unsatisfactory\,\nsince it produce
 s artificial oscillations (untolerable in the collaboration with surgeons!
 ).\nFor this reason\, the author and his coworkers have\nsuggested a furth
 er modification called ''contact-stabilized Newmark method''. This scheme 
 now is energy dissipative and avoids artificial oscillations. However\, th
 e new scheme escapes the usual domain of consistency theory for numerical 
 integration.\nAfter a long investigative period\, we meanwhile found the t
 heoretical key to this kind of integrators.\nThe new theoretical character
 ization requires bounded variation in terms of\na physical energy function
 al that includes kinetic energy\, elastic energy\, and visco-elastic energ
 y. First numerical findings (a few days old) for an adaptive stepsize cont
 rol in a Hertzian contact problem will be presented.\n\n
LOCATION:MR14\, CMS
END:VEVENT
END:VCALENDAR