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Wijk, Kasper van

Publications and source records attributed to Wijk, Kasper van.

3 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Laser Excitation of a Fracture Source for Elastic Waves

We show that elastic waves can be excited at a fracture inside a transparent sample by focusing laser light directly onto this fracture. The associated displacement field, measured by a laser interferometer, has pronounced waves that are diffracted at the fracture tips. We confirm that these are tip diffractions from direct excitation of the fracture by comparing them with tip diffractions from scattered elastic waves excited on the exterior of the sample. Being able to investigate fractures - in this case in an optically transparent material - via direct excitation opens the door to more detailed studies of fracture properties in general.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Multicomponent wavefield characterization with a novel scanning laser interferometer

The in-plane component of the wavefield provides valuable information about media properties from seismology to nondestructive testing. A new compact scanning laser ultrasonic interferometer collects light scattered away from the angle of incidence to provide the absolute ultrasonic displacement for both the out-of-plane and an in-plane components. This new system is tested by measuring the radial and vertical polarization of a Rayleigh wave in an aluminum half-space. The estimated amplitude ratio of the horizontal and vertical displacement agrees well with the theoretical value. The phase difference exhibits a small bias between the two components due to a slightly different frequency response between the two processing channels of the prototype electronic circuitry.

36 MATERIALS SCIENCE↗