Energy transfer by a secondary acoustic source through friction-induced vibrations: a power flow analysis

Friction Induced Vibrations occur in many different contexts, from automotive industry to musical instruments, and are often investigated for their detrimental effects such as surface damage and dynamical instabilities. In this article, a mechanical device exploits Friction Induced Vibrations to transfer energy in a structure from a primary ambient low-frequency vibrational field towards a secondary acoustic field with a higher and wider frequency content. This device constitutes a Secondary Acoustic Source for the structure. An approach is proposed to quantify the energy flow between the primary and secondary acoustic fields from the sole measurement of acceleration signals at a finite number of points on the experimental structure. These results pave the way towards the optimisation of the energy transfer by the Secondary Acoustic Source and, as such, towards its use for Structural Health Monitoring applications.