Study On Damage Location Of Composite Plate Structure Based On Lamb Wave Nonreflective Boundary

In recent years,composite laminates have been widely used in aerospace applications due to their high strength,high stiffness,excellent thermal stability,and fatigue resistance.The structural health monitoring technology(SHM),especially the Lamb wave structure health monitoring technology with the characteristics of longdistance propagation in the thin plate structure,high sensitivity to damage,and realtime characteristics,has gained the attention and research of scholars all over the world.However,the anisotropic properties of composite materials and the existence of structural boundaries make the propagation of Lamb waves extremely complex,thus affect the monitoring of the damage location.In this paper,the propagation characteristics of Lamb waves in the composite material under the non-reflected waveabsorbing boundary of the COMBIN14 buffer in the finite element simulation structure detection are studied.On this basis,the public cut circle is introduced to improve the ellipse positioning method and conducted simulation and experimental research.First,the propagation characteristics of Lamb waves in composites are introduced.By studying the theory of wave-absorbing boundary,we found that the traditional nonreflected wave-absorbing boundary can not effectively absorb Lamb wave,and the COMBIN14 buffer unit was introduced,which improved the setting of the nonreflected wave-absorbing boundary.The effects of the parameters such as the length of the absorbing boundary,the direction of the COMBIN14 element,and the center frequency of the excitation signal on the effectiveness of the non-reflected microwave absorption at the boundary of COMBIN14 are studied.After that,the APDL code was written using commercial finite element software ANSYS,and a simulation model including the non-reflected wave-absorbing boundary of the composite material plate,piezoelectric transducer and COMBIN14 buffer was established to realize the excitation of Lamb wave in the composite material plate structure.The boundary reflection response signal is received.According to the Lamb wave propagation characteristics,the ellipse positioning method was improved,and a common external tangent circle positioning method was proposed.Numerical simulation was performed.The superiority of the method was compared with the sixpoint intersection fitting positioning method for damage location and damage degree monitoring.Finally,based on the graphical programming software LABVIEW and NI PXIe-1062 Q integrated chassis and other hardware equipment to build a composite damage monitoring experimental platform.The effects of different diameter circular holes and different monitoring areas on the damage location and damage estimation of the Lamb wave public elliptical circle elliptical positioning method were studied.The feasibility of this method was also verified.