Time domain phase coherence based algorithm for impact source reconstruction

The characterization of vibroacoustic sources using microphone arrays in the time domain is still challenging because of the bad conditioning and extensive computational resources required to solve the associated ill-posed problem. The Near-field Acoustical Holography (NAH) framework and the Time-Reversal techniques are among the approaches proposed to solve this problem. However, such techniques involve either dense microphone arrays in the vicinity of the sources to be characterized or high computational complexity. This work proposes a new Time-Domain Phase Coherence algorithm (TD-PCa) based on the phase coherence principle widely used in the fields of image processing and ultrasound imaging. The proposed TD-PCa is numerically and experimentally validated using a regular 121 microphone array located in front of an impacted, ba ed, simply-supported plate in an anechoic chamber. The resulting vibration field is reconstructed with the proposed TD-PCa and compared with the vibration field estimated with the Delayand- Sum (DAS) standard approach. Moreover, the imaging results are compared with vibration field measurements conducted on the plate using the deflectometry technique with a high-speed camera. The results show that the acceleration field reconstructed with the proposed TD-PCa is in good agreement with the vibration field measured optically.