Experimental research on detection in fastener-loosing of aircraft panel by correlation function

Fastener loosing is a common damage of aircraft panel. A novel damage detection method based on the Cross Correlation Function Amplitude Vector (CorV) is proposed. It is verified that under random excitation with specific frequency spectrum, the CorV of structure only depends on the frequency response matrix of the structure, and the normalized CorV is endowed with a specific shape to apply to detect damages in a structure under random excitations. The CorVs of the intact and damaged panel are calculated with its dynamic strain responses under random excitation governed by the response signal of an airplane model in wind tunnel test. The loosed bolts near by the sensors can be accurately located with the maximum value of the relative change between CorVs of damaged and intact structures, and the loosed bolts between the sensors can also be approximately detected. The CorV is obtained directly from the measured time domain responses of the structure under random excitation, so the CorV based damage detection method is efficient for structural health monitoring of aircrafts.