MUSIC Algorithm Based Structural Health Monitoring For Aircraft Structures

In last decades,since it is easy to be arranged on complex aircraft structures using the compact sensor array,multiple signal classification(MUSIC)algorithm is gradually introduced to the Lamb wave based structural health monitoring,which has the ability to realize direction scanning and monitor multiple sources.However,for applications of impact/damage localization on aircraft structures and corrosion monitoring on complex aircraft metal structures,many issues are still open.To realize MUSIC based structural health monitonng on complex aircraft structures,deep researches are performed for the optimization and applications of MUSIC algorithm.The main innovations are as follows.(1)To improve the MUSIC based impact monitoring method,this paper first analyzes and demonstrates the influence of measurement precision of the phase velocity on the localization results of the MUSIC impact localization method.In order to improve the accuracy of the phase velocity measurement,a single frequency component extraction method is presented.Additionally,a single frequency component based re-estimated MUSIC algorithm is proposed to reduce the localization error caused by the anisotropy of the complex composite structure.(2)The corrosion scattered Lamb waves obtained by using a single actuator is relatively weak,making the signal-to-noise ratio(SNR)of the scattered signals low and resulting in the low precision of MUSIC based corrosion localization.To deal with this problemrtransmitter beamforming is introduced to MUSIC algorithm by using a dual array.Based on this research,a joint beamforming-spectrum based MUSIC algorithm is proposed to realize corrosion localization,which could improve the SNR of damage scattered signals.(3)The linear sensor array based SHM methods has the problem of blind area at the angles close to 0?and 180.To monitor corrosion damages at the blind area,a weighted lamge fusion based MUSIC algorithm is proposed.Also,to evaluate the corrosion severity,an eigenvalue based corrosion index is proposed,which provides monitoring abilities of both the position and seveity of the corrosion damage.(4)For applications on complex composite structures,the performance MUSIC algorithm is inevitably influenced by the array error caused by structural anisotropy,sensor position error and wave packet aliasing.To localize damage on complex composite structures,a novel array error calibration based MUSIC algorithm is proposed,which could compensate the array error jointly along different directions and improve the localization precision and reliability of MUSIC algorithm.