Acoustic source localization on a plate suspended at an air–water interface

Acoustic waves can be ideal for remote sensing and structural health monitoring because they carry source information and can be measured without contact. However, traditional time-of-flight array methods for source localization are ill-suited for structural engineering applications. Specifically, for a plate suspended at an air–water interface, the coupling between the vibrating structure and the surrounding mediums complicates localization efforts. Thus, source localization experiments were conducted using Matched Field Processing (MFP) for a 0.91-m diameter round aluminum plate suspended at an air–water interface and excited by the impact of a 1.3-cm diameter stainless-steel ball bearing dropped from 11.4-cm. A remote linear seven-microphone array placed 10.5-cm above the plate in the air and a remote linear seven-hydrophone array placed 13.5-cm below the plate in the water measured the sound radiated by the 0.64-cm-thick plate at frequencies up to 20 kHz. MFP array signal processing localization techniques were used along with a physics-based finite element acoustic model to localize the impact excitation on the structure. Source localization results using each set of acoustic pressure measurements independently are compared to results using both sets of acoustic pressure data. Localization success rates in a noisy environment are also presented. [Work sponsored by a SMART Scholarship.]