Coupling of multi-tone signatures and fuselage structures

Necessary for an optimal development of the fuselage design and the acoustic concept is to get a better understanding on the near field noise to structure coupling. In the context of this work a measurement is described to determine the main physical mechanism for coupling of deterministic sound sources on a doubly ribbed fuselage structure. In this particular test case an A400M fuselage was excited by a single tone excitation generated by a loudspeaker array. The phase controlled loudspeaker array is able to create an acoustic field with an arbitrary relationship between the frequency and the wave number. It was found out that the response of the structure varies significantly by constant sound pressure level and constant frequency of the excitation only by changing the wave number of the excitation field.