A new information theory for ultrasonic nondestructive evaluation based on differential wave fields

In this paper a new fundamental information concept for ultrasonic NDE is introduced. It is demonstrated that differential wave fields with respect to a system parameter P contain structural information about this parameter and about how it affects the measured system response. This can be quantitatively formalized by introducing a balance equation for structural information in analogy to Poynting’s theorem for elastic energy. In the paper, we consider several aspects of the new information approach, such as information density, information flux vector, as well as information sources and sinks. We visualize how structural information in an ultrasonic field can be generated and annihilated and how it propagates to the sensors. We finally discuss possible potential impacts on NDE, SHM, numerical simulation, and machine learning.