Ultrasonic Phased Array Inspection Technology For Integrated Composite Structures

Due to the occasional fluctuations of curing parameters and external loads,the defects of aircraft integrated composite structures may be caused.Defects reduce the mechanical properties of integrated composite structures and bring serious security risks to their installation.However,the existing conventional nondestructive inspection technologies are difficult to inspect the defects of integrated composite structures,especially the in-situ testing in service.In this study,a set of ultrasonic inspection technology was developed for non-uniform integrated composite structures.The main research contents and results are as follows:First,to study the acoustic propagation characteristics of composite materials by inclined ultrasonic wave.According to the microstructure characteristics of composite materials,an acoustic model for composite layer-resin basic structure was established to study the reflection and refraction effects of the layer-resin interface by ultrasonic inspection.The research results show that the ultrasonic wave is inclined to the layer-resin interface,the layer can be regarded as a homogeneous medium.Second,the experimental evaluation of the ultrasonic phased array scanning imaging system was carried out.In view of the complexity of acoustic propagation of ultrasonic phased array synthetic acoustic waves in the integrated composite structure,a standard test block for the calibration of composite materials was designed and manufactured in a pioneering way,which was used for wave pattern conversion experiment of incident acoustic waves,scanning deflection angle and time baseline ratio calibration of ultrasonic phased array scanning imaging experimental system.Therefore,the inspection effect of ultrasonic phased array inclined sector scanning imaging experimental system for integrated composite structure was evaluated.Third,based on the simulation method and the experimental method,the critical inspection parameters of the ultrasonic phased array scanning imaging system for the integrated composite structures were optimized.Tilt for ultrasonic phased array inclined sector scanning acoustic field finite element simulation and experiment for integrated composite structures,the variation law of echo signal amplitude and scanning image characteristics with frequency,wafer shape,scanning deflection angle,aperture and focusing depth were explored,and the inspection parameters of the ultrasonic phased array scanning imaging system were determined and optimized by comprehensive analysis of simulation and experiment results.Fourth,the application research of ultrasonic phased array testing for integrated composite structure workpieces were carried out.The optimized ultrasonic phased array inspection system was applied to inspect natural defects in actual workpieces,the inspection results showed that the proposed ultrasonic phased array inclined sector scanning inspection technology could realize the in situ inspection of the aircraft exterior surface in the R-zone of the closed integrated composite structure,which breaked through the technical bottleneck that the R-zone could not be inspected after service,and established an effective nondestructive inspection technology for its health monitoring.