A Research On Ultrasonic Testing Technology Based On Recurrence Analysis For Defects Detection In Carbon Fiber Reinforced Plastics

With the widely use of carbon fiber reinforced plastics(CFRP)in many fields such as aerospace,automobile and so on,the significance of nondestructive testing(NDT)technology for CFRP has become increasingly prominent.In the process of manufactur and use,defects will inevitably grow in CFRP.The ultrasonic nondestructive testing technology is one of the main methods for CFRP defects.However,in the face of more and more complex shapes of CFRP and thick-section CFRP components,the application of tradional ultrasonic nondestructive tesing methods for CFRP which deeply depend on back-wall echo is limited.Aimed at this problem,a new method of ultrasonic testing technology for CFRP based on recursive analysis was proposed.The research work and achievements of this paper are as follows.(1)This paper studies the features and application scopes of the current ultrasonic nondestructive testing technology for CFRP.In order to deal with the problem mentioned above,the method of defect testing for CFRP based on backscattering signal analysis is proposed.Then theultrasonic backscattering signal is studied and analyzed.(2)An overview of the basic theory and algorithms of the recurrence plot(RP)and recurrence quantification analysis(RQA)is introduced.This paper investigates both large-scale and small-scale patterns of RP and the property of different RQA parameters.Based on the nonlinear characteristics of ultrasonic propagation in CFRP,the feasibility of dealing with CFRP ultrasonic backscatter signals by recurrence analysis to detect defects is studied.(3)With using the RP and RQA to process typical ultrasonic testing signals to detect defects,this paper verify the feasibility of recurrence analysis in the application of defect detection in ultrasonic testing.(4)The method of RP and RQA is used to estimate porosity of CFRP and detect the defects of concentrated pores,inclusions and resin rich.The change of RP and RQA parameters with different porosity is studied under different analysis parameters.The different characteristics of RP and RQA parameters for the signal of concentrated pore,inclusion and rich resin defects are studied.