Materials Characterization Using Acoustic Nonlinearity Parameters and Harmonic Generation: Engineering Materials

Most of the NDE effort using ultrasonics to assess engineering materials has been in the detection of cracks or crack-related phenomena. Other questions involving, for example, NDE measurements of temper or the state of fatigue prior to cack initiation, while very important to material scientists and design engineers, are not easily investigated using ultrasonic techniques based on linear theory. Recent work indicates, however, that the use of ultrasonics based on nonlinear concepts provides potentially useful information about material processing and certain pathological states that develop in materials as they are used