Watching and Listening to Fracture

Abstract:
This talk will report very high-speed imaging of fracture induced by fluid, combined with acoustic measurements to probe the nature of the fracture.  The velocity of the fracture initially moves near the speed of sound, much faster than the fluid.  Later the fracture advances more slowly, but typically leads the fluid.  Complimentary measurements of the strain in the solid are performed with a new optical measurement technique, Dynamic Speckle Holography, which will also be described.  Analysis of the acoustic signals can be correlated with the images, and can provide insight into passive acoustic emission during fracture.

Bio:
Weitz received his PhD in physics from Harvard University and then joined Exxon Research and Engineering Company, where he worked for nearly 18 years. He then became a professor of physics at the University of Pennsylvania and moved to Harvard at the end of the last millennium as professor of physics and applied physics. He leads a group studying soft matter science with a focus on materials science, biophysics, microfluidics and flow in porous media. Several startup companies have come from his lab to commercialize research concepts.