Acoustic emission beamforming for enhanced damage detection

摘要

As civil infrastructure ages, the early detection of damage in a structure becomes increasingly important for both lifesafety and economic reasons. This paper describes the analysis procedures used for beamforming acoustic emissiontechniques as well as the promising results of preliminary experimental tests on a concrete bridge deck. The method ofacoustic emission offers a tool for detecting damage, such as cracking, as it occurs on or in a structure. In order to gainmeaningful information from acoustic emission analyses, the damage must be localized. Current acoustic emissionsystems with localization capabilities are very costly and difficult to install. Sensors must be placed throughout thestructure to ensure that the damage is encompassed by the array. Beamforming offers a promising solution to theseproblems and permits the use of wireless sensor networks for acoustic emission analyses. Using the beamformingtechnique, the azmuthal direction of the location of the damage may be estimated by the stress waves impinging upon asmall diameter array (e.g. 30mm) of acoustic emission sensors. Additional signal discrimination may be gained via arrayprocessing techniques such as the VESPA process. The beamforming approach requires no arrival time information andis based on very simple delay and sum beamforming algorithms which can be easily implemented on a wireless sensor ormote.