Theories of noise and vibration transmission in complex structures

Theories for analysing the vibrational behaviour of complex structures are examined, parallels being drawn with several other areas of physics in which problems of wave propagation in inhomogeneous media are studied. There are three main stages to the investigation. First, the response to random driving of a single, essentially homogeneous, system is examined. The second, and much more detailed, discussion concerns energy transport between discrete coupled subsystems. In particular, we investigate an approach to this problem which is known as statistical energy analysis. The third main topic is the phenomenon of Anderson localisation as it applies to certain problems of sound and vibration transmission-the phenomenon is much better known in the field of solid-state physics. Applications of it to vibration are of interest in themselves, and also shed light on the theoretical basis of statistical energy analysis, which is a diffusive transport theory. This review was received in its present form in June 1985.