Confocal scanning based MUSIC damage imaging algorithm for high guided waves attenuation structures

Abstract Guided waves based structural health monitoring methods are potential for practical applications, since they are sensitive to small damage and could realize large area monitoring. However, guided waves attenuate seriously on some structures, such as carbon fiber composite structures, honeycomb skin structures, thermal protection structures of silicone polymer composites, and so on. Specially, the low SNR (Signal noise radio) of guided waves, resulting from high attenuation, limits the accuracy of guided waves based methods. In addition, these high attenuation structures are usually anisotropic, which make the propagation velocity related damage imaging methods not accurate. To solve this problem, a novel confocal scanning based multiple signal classification (MUSIC) damage imaging method with array steering vectors correction is proposed in this paper. Confocal scanning is carried out to make the excitation guided waves focused on special positions and MUSIC algorithm is used to synthetic the received guided waves, scattered from damage, to further improve the damage imaging accuracy. At last, an experiment on the carbon fiber composite plate, considered as the high attenuation structure, is carried out to verify this proposed method. Experimental results show that this method can recognize damage imaging within 2° and 18 mm deviations in angle and distance, respectively.