Active structural excitation as known source for structure-borne noise research

Abstract

An important element required to investigate structure-borne noise propagation mechanisms is the ability to have full knowledge and control over the excitation sources responsible for the disturbance. Such information can help to understand propagation and radiation of energy once known forces are introduced into the structure. However precise control over structural excitation tends to be disregarded and generalized to simple broadband excitation. Cabin noise research could benefit from having the ability to reproduce on the structure a more realistic excitation, such as engine induced vibrations. Moreover, being able to reproduce engine excitation under laboratory conditions can be highly beneficial and could potentially allow to perform, from the vibro-acoustic point of view, flight tests on the ground. If the idea is to inject into the structure an exact copy of an arbitrary reference force signal, an active controller can be used in order to compensate force signals to obtain such copy at the injection point on the structure. The system developed is able to perform simultaneously the system identification and the control of injected forces. The following work describes the adaptive MIMO controller implemented for such an objective and discusses test results obtained in the laboratory.