Research On Lamb Wave Detection And Imaging Positioning Of Aircraft Skin Composites

Resin matrix composites with high specific strength,good fatigue resistance performance,designability and other significant advantages are widely used in aerospace,automotive industry,sports,environmental protection facilities.Multi-angle mixing layer of carbon fiber reinforced plastics(CFRP)as the main material of aircraft skin,leading a role of protection.However,due to the product process stage and in service,all sorts of damage of components is occurred which will greatly affect the using performance,and even make the whole structure system failure.In the composite laminates,the most common but difficult for examination is the internal delamination and it bears safety risks during its usage.Therefore,the delamination of online monitoring to the CFRP is very significant.This paper puts forward using ultrasonic Lamb wave monitoring technique and the piezoelectric pieces as self-motivation sensors to obtain the information in the test board,researching the reverse problem of delamination defects,thus improving the quality of artifacts made by CFRP.The main content of this article are roughly as follows:Firstly,this paper analysis propagation characteristics of Lamb wave in the isotropic and anisotropic materials,completely obtains the dispersion equation of Lamb wave.And on the basis of Disperse drawing dispersion curve of organic glass and carbon fiber laminate,the relationship between the frequency and wave velocity is established.Based on this,we put forward the incentive theory of the single mode about Lamb wave,and then choose the ideal mode combining with wave structure.Analyzing and deducing the imaging principle of time reversal algorithm and data fusion method.Secondly,creating a healthy CFRP and a carbon fiber composite laminate containing the delamination damage in the finite element simulation software,on the one hand,from the perspective of statics,analyzing the influence of ply orientation on buckling effect,the results show that the layers of shell with different Angle different corresponding stress nephogram,the direction of the tolerance is consistent with the fiber direction will reduce the deformation rate of the laminate to a certain extent.On the other hand,Based on the finite element analysis software ABAQUS,studying the way of acquiring lamb signal and defects imaging algorithms.Also,using piezoelectric array acquire Lamb wave propagation signal in a board which is included single damage or multiple damage.Applying improved time reversal method and data fusion method for reconstructing signal,displaying composite delamination defects in two-dimensional image according to four points arch technique.Finally,in order to verify the reliability and validity of simulation imaging algorithm,producting a CFRP board with a single delamination defect for carrying on Lamb wave defects experiment.And making a comparison of ultrasonic water C scan detecting technology imaging results,the calibration of the results show that the imaging method for the determination of defect position is accurate and effective.The research results show that the improved time reversal method can strengthen the target signal.To a single damage detection imaging,time reversal localization algorithm can greatly improve the location accuracy;but if the defect is more than one,it will be invalid and data fusion method can accurately identify the quantity and the location of the defects.