Anisotropy compensated MUSIC algorithm based composite structure damage imaging method

Multiple signal classification (MUSIC) algorithm is a promising method in guided wave based structural health monitoring (SHM) area because of its directional scanning ability and easy arrangement of the sensor array. However, since composite structures are anisotropic, guided waves have different velocities along different directions, i.e. propagation anisotropy. For different scanning positions of the monitoring area in MUSIC algorithm, the directions from the scanning position to the sensor array are different. Even for the same scanning position, the directions from the scanning position to each element in the sensor array are also different. If a fixed velocity is used in MUSIC algorithm, there must exist sensor phase errors in steering vectors of MUSIC algorithm caused by structural anisotropy, as well as the sensor position error, resulting in the localization error. To reduce the localization error caused by sensor phase errors, an anisotropy compensated MUSIC algorithm is proposed, which could compensate different kinds of sensor phase errors jointly and improve the localization precision and reliability of MUSIC algorithm. The proposed method is verified on a reinforced composite panel with one T-stiffener. Experimental results show that the proposed method can realize damage localization with an obviously improved accuracy.