Summary: A THEORETICAL MODEL FOR THE ULTRASONIC
DETECTION OF SURFACE-BREAKING CRACKS
WITH THE SCANNING LASER SOURCE TECHNIQUE
Irene Arias and Jan D. Achenbach
Center for Quality Engineering and Failure Prevention.
Northwestern University, Evanston, IL 60208
ABSTRACT. In work reported at last year's QNDE meeting, a first step towards the develop-
ment of a model for the Scanning Laser Source (SLS) technique was presented, which provides
an analytical formulation for the transient response of an isotropic, homogeneous, linearly elas-
tic half-space submitted to a pulsed laser line source operating in the thermoelastic regime.
The formulation takes into account optical penetration into the material and thermal diffusion
from the source, and is therefore a suitable representation not only for the far field, but also for
the field near the laser source, where these effects become significant. In the present paper, we
report the progress made in the numerical analysis by the Boundary Element Method of the
interactions of the previously obtained laser generated field with surface-breaking cracks. Some
preliminary simulations of SLS experimental observations are presented.
Surface-breaking cracks in a structure can be ultrasonically detected using Lamb
and Rayleigh waves. Conventional ultrasonic flaw detection methodologies require the
generation of an ultrasonic wave packet that travels through a structure and interacts