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CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20260827T002245Z
LAST-MODIFIED:20141027T144059Z
DTSTART:20141104T203000Z
DTEND:20141104T213000Z
UID:event1325@bu.edu
URL:http://physics.bu.edu/internal/events/show/1325
SUMMARY:Unlocking mysteries of crack propagation: hidden paths and instabil
	ities 
DESCRIPTION:Featuring Alain Karma\, Northeastern University\nHosted by: Dav
	id Campbell\nPoster: http://physics.bu.edu/internal//files/get/110414-karma
	.pdf\n\nPart of the Physics Department Colloquia Series.\n\nAbstract:\nCrac
	k propagation is the dominant mode of mechanical failure of most man-made a
	nd naturally occurring materials. Understanding this phenomenon poses a num
	ber of challenges for physicists\, materials engineers\, and Hollywood film
	 makers that are addressed in this talk. Firstly\, and mostly of interest t
	o physicists\, crack propagation is a truly multiscale phenomenon with no c
	lear separation of scale between atomic and continuum scales\, i.e. no simp
	le hydrodynamic limit. Consequently\, how to formulate equations of motion 
	for cracks is still an open question. Secondly\, in many situations\, crack
	 fronts become dynamically unstable\, thereby following convoluted paths in
	side a material and forming complex patterns that are hard to deduce. Those
	 paths need to be guessed from post-mortem analysis of crack surfaces due t
	o the inherent difficulty to visualize the actual front evolution during th
	e failure process. Thirdly\, materials with desirable mechanical properties
	 such as high strength and fracture toughness are generally highly heteroge
	neous\, as exemplified by the hierarchical composite structure of bone\, an
	d those heterogeneities greatly complexity failure mechanisms. This talk pr
	ovides an introduction to the basic physics of cracking and discusses a cla
	ss of continuum models of brittle fracture that self-consistently bridges t
	he descriptions of short scale failure and continuum elasticity. The power 
	of this approach to reveal hidden crack paths and understand crack-front in
	stability mechanisms is then demonstrated for selected experiments. The tal
	ks concludes with prospects for improving materials design and film making.
LOCATION:SCI 109\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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