Search

Beamforming is widely used in structural health monitoring (SHM) systems for impact or damage localization. Beamforming directionality is achieved by the constructive interference of sensor wavefronts, which results in a significant amplification of the measured signal in a particular direction. For beamforming applications, the cost per sensor is typically significant, because of the sensor itself, and the associated electronics. Therefore, in order to minimize the cost of SHM in practice, it is highly desirable to reduce the number of sensors. Beamforming with an array of sensors requires an advanced signal processing technique to detect the direction-of-arrival (DOA). In addition, by deploying more sensors, better detection accuracy can be achieved. In this paper, the non-equidistant linear sensor array is proposed, to obtain lower costs while guaranteeing reasonable detection accuracy. In addition, the proposed sensor deployment scheme is able to reduce the effects of “spatial aliasing,” which phenomenon is typically encountered in the equidistant linear sensor array layout. To validate the performance of the proposed non-equidistant linear array technique in SHM applications, several finite element models (FEM) simulation and experimental investigations are carried out. Different sensor array layouts are also compared to optimize the performance of the non-equidistant linear array.

Beamforming or phased array is widely used in structural health monitoring (SHM) systems for source localization. This localization is achieved by the constructive interference of signals measured by sensors in different positions. The uniform linear array (ULA) is one of the most commonly used beamforming array layouts due to its low complexity and high reliability. Unfortunately, ULA has the disadvantage of very low resolution when the direction of arrival (DOA) approaches certain directions. In order to overcome this problem, the double L-shape array is employed by adding only one sensor to the ULA. This sensor array uses the time difference of arrival information to estimate the DOA, which has high resolution in all directions except for the direction very close to vertical. Due to the blind area of the ULA beamforming and double L-shape sensors array, we combine the two methods and proposes a novel combined sensor array configuration which has no blind area at all. In addition, this novel combined sensor array layout uses a fewer number of sensors, which can reduce the cost of SHM practice significantly. Several numerical investigations are carried out to demonstrate the performance of the proposed sensor array.