Group Dictionary Equivalent Source Method for Sparse Nearfield Acoustic Holography

In this article we propose a novel methodology for the non-invasive estimation of the geometry of the modes of vibration of a vibrating structure, which uses the signals captured by a microphone array placed in close proximity of the vibrating structure. We propose a measurement approach based on an efficient formulation of the Nearfield Acoustic Holography (NAH) problem, using a small sets of equivalent sources that are able to represent a continuous vibrating structure. In this new reformulation of the solution, a Group Dictionary Equivalent Sources Method is developed, which combines the efficiency and flexibility of equivalent sources, with a sparse reconstruction scheme that takes into account prior knowledge about the mechanical behavior of the object under investigation computed through FEA.