Blind identification using inverse Patch Transfer Function (iPTF) method
Abstract
An important object of vibration and noise reduction and control is to identify and localize the vibration and noise sources. Many inverse methods, like Nearfield Acoustic Holography, have been developed in acoustics in the last decades. Among others, the iPTF method, allows the reconstruction of the acoustic fields (pressure, velocity, intensity) directly on the vibrating structure surface even when it has a complex shape. In addition, measurements can be done in non-controlled acoustic environments. The concept of iPTF is based on the application of Green's identity on any closed virtual volume defined around the source. The reconstruction of sound source fields combines discrete acoustic measurements performed at accessible positions around the source with acoustic impedance matrices. In the present work, blind identification of the vibratory fields is proposed. The "blindness" has here two meanings:-the identification of the velocity field of a vibrating structure can be blind if obstacles mask parts of the structure to characterize.-the identification can be blind if the velocity field is the result of the combination of several unknown sources and if one wants to separate the contribution of each source. Some numerical and experimental results will be shown to illustrate both aspects of the blind identification.
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