Ultrasound is currently used in a wide spectrum of applications ranging
from medical imaging to metal cutting. This book is about using
ultrasound in nondestructive evaluation (NDE) inspections. Ultrasonic
NDE uses high-frequency acoustic/elastic waves to evaluate components
without affecting their integrity or performance. This technique is
commonly used in industry (particularly in aerospace and nuclear power)
to inspect safety-critical parts for flaws during in-service use. Other
important uses of ultrasonic NDE involve process control functions
during manufacturing and fundamental materials characterization studies.
It is not difficult to set up an ultrasonic NDE measurement system to
launch waves into a component and monitor the waves received from
defects, such as cracks, even when those defects are deep within the
component. It is difficult however to interpret quantitatively the
signals received in such an ultrasonic NDE measurement process. For
example based on the ultrasonic signal received from a crack, what is
the size, shape, and orientation of the crack producing the signal?
Answering such questions requires evaluation procedures based on a
detailed knowledge of the physics of the entire ultrasonic measurement
process. One approach to obtaining such knowledge is to couple
quantitative experiments closely with detailed models of the entire
ultrasonic measurement system itself. We refer to such models here as
ultrasonic NDE measurement models. In other areas of engineering, models
have revolutionized how engineering is practiced. A classic example is
the impact of the finite-element method on elastic stress analysis.
