Propagation Characteristics Of Lamb Waves Under Static Load

Structural Health Monitoring(SHM)technology based on piezoelectric sensors and Lamb waves is a research and application hotspot in the field of aviation.However,when SHM technology is applied in the service environment of aviation structures,many uncertainties that change with time will affect the propagation characteristics of Lamb waves,resulting in the fact that the signal characteristics of Lamb waves can not reflect the real state of structures and directly affect the reliability and stability of damage monitoring.In order to solve the problem,this paper studies the propagation characteristics of Lamb waves under static load from three aspects: the mechanism of the influence of static load on Lamb wave propagation,the experimental and regular analysis on Lamb wave propagation under static load,and the modeling and simulation method of Lamb wave propagation under static load.(1)Firstly,based on the basic principle of piezoelectric effect and Lamb wave propagation,the excitation,propagation and sensing model of Lamb wave based on piezoelectric sensor under static load was studied and established.Then,the influence mechanism of static load on the velocity and amplitude of Lamb wave propagation was analyzed theoretically,including the change of Lamb wave propagation velocity caused by acoustic-elastic effect caused by load.The variation of Lamb wave propagation amplitude was due to the non-linear change of the electric constitutive equation.(2)The experimental study of Lamb wave propagation characteristics under static load was carried out.The effects of static load on Lamb wave propagation velocity and amplitude were systematically studied and summarized from three aspects: Lamb wave frequency,structural thickness and load direction.The results were basically consistent with the mechanism analysis of the effects of static load on Lamb wave propagation characteristics.At the same time,nonlinear numerical model of the influence of main piezoelectric constants was also built.(3)The simulation method of Lamb wave propagation with piezoelectric sensor under static load based on COMSOL Multiphysics finite element software was studied.The mechanical-electrical multi-physical coupling simulation model of Lamb wave propagation under unidirectional static load of isotropic plate structure was established.The direct integrated simulation problem of acoustic-elastic effect,piezoelectric non-linear constitutive model,static load and transient Lamb wave was solved.The simulation results of Lamb wave velocity and amplitude were in good agreement with the experimental results.