Crack Imaging with Time Reversal - Experimental Results
The videos below demonstrate the focusing of elastic energy onto a crack as a result of using the TR NEWS process. (Ulrich et al, 2007). Both movies show the elastic energy as measured by the laser vibrometer. The movies begin at the time of termination of the rebroadcast signals.
These photos show the arch used in these experiments. The photo on the right displays the area which was scanned by the laser vibrometer and corresponds to the same area displayed in the movies below.
For more information, contact TJ Ulrich.
Click the images below to view the associated videos.
Arbitrary Frequency -> No Focusing
An arbitrary frequency is rebroadcasted that does not stem from wave mixing at the crack. Throughout this video there is no focusing in the region of the nonlinear scatterer. Furthermore, the elastic energy contained in the scan area is greatly reduced from what appears in the difference frequency movie (above), despite identical experimental settings (i.e., rebroadcast signal amplification, same sample, same transducer array). The energy feature along the sample arch appears in other movies as well which may imply a geometric focusing.
TIME REVERSAL WORK at LANL
- Time Reversal Home
- Source Reconstruction Using Time Reversal
- Robustness & Efficiency of Time Reversal Acoustics in Solid Media
- Audio Example of Time Reversal - Speech Privacy
- Crack Imaging with Time Reversal - Experimental Results
- Time Reversal Nonlinear Elastic Wave Spectroscopy
- Experimental Facilities and Resources
- Time Reversal of the 2004 (M9.0) Sumatra Earthquake