Lamb Wave Structural Damage Monitoring Technology Based On Active And Passive Methods Synergism

Structural Health Monitoring(SHM)is the technology of real-time and on-line monitoring for structural status.Thus,it plays an important role in reducing economic losses and ensuring the safety of personnel.At present,the research direction of SHM mostly focuses on single active or passive monitoring mode,which can not reflect real-time and full time monitoring advantages well.In view of the extensively studied Lamb wave active and passive monitoring technology,the active and passive cooperative Lamb wave structural damage monitoring technology is studied based on the advantages and disadvantages of the active and passive monitoring methods in the stage of damage generation to development.The technology includes the research of mechanism of active and passive coordination,the development of integrated monitoring system,the improvement of active and passive Lamb wave monitoring method and the proposal of active and passive cooperative damage monitoring method.The contents of the study and the results obtained are as follows:(1)The propagation characteristics of Lamb wave in the plate structure and the mechanism of excitation and sensing are analyzed based on the characteristics of Lamb wave sensitivity to damage.Meanwhile,the basic way of single passive Lamb wave damage monitoring is also studied.(2)The mechanism is studied and integrated system is developed based on active and passive coordination.The integrated system not only solves the discrete system's problems of complex operation,large area and low monitoring efficiency,but also realizes the convenience of the monitoring process,the miniaturization of the volume,and the high efficiency of the monitoring mode.(3)The scheme of double-line linear sensors is studied based on the existing sensor networks for SHM and the mechanism of active and passive coordination.The scheme can be reused in both active and passive monitoring modes simultaneously.Furthermore,the passive location and imaging algorithm based on trigonometric compensation is proposed.The experimental results show that the proposed algorithm has better positioning accuracy and less complexity.Then,an active trigonometric compensation location and imaging algorithm based on passive location points is proposed.The experimental results show that the algorithm uses passive positioning point to correct the active damage positioning area.(4)The active imaging fusion algorithm based on the circular domain of the passive location point is proposed,in combination with the improved active and passive location imaging algorithm.Furthermore,the cooperative fusion algorithm is improved according to the different sensing information between active and passive ways.The experimental results show that the algorithm integrates the advantages of passive method to monitor the impact point accurately and the advantage of active method to monitor the damage area precisely,which provides more abundant structural damage information.