Phased Array Ultrasonic-based Debonding Detection Of Composite Material Engine Housing

With the rapid development of composite industry,composite shell engine is widely used.The engine shell and the insulation layer are connected by fiber and resin adhesive.During the manufacturing process,the fiber tension will cause defects such as debonding and air bubbles.These defects will affect the performance or safety of the rocket engine.Therefore,in the process of production,the bonding interface needs to be accurately and comprehensively tested.Phased array ultrasound can realize multi-angle and wide range adjustment to scan the internal defects of the object comprehensively.However,the focus rule,imaging mode,and detection signal in the detection process affect the final detection result.This paper is based on the ultrasonic phased array sound beam control and debonding detection theory to study composite material interface debonding detection.In this paper,the beam propagation model of phased array ultrasound in the composite bonding structure is established,the delay time of each copy element is calculated according to different focusing rules,and the difficulties of beam propagation in the composite material are analyzed.The relationship between the problematic signal-to-noise ratio(SNR)and the low detection accuracy of the linear scan echo,the characteristics of multi-array synthetic aperture imaging and sector imaging for interface debonding detection were analyzed,and the imaging results were processed by variational mode decomposition(VMD)to improve the recognition degree of defects;The full matrix full focus phased array scanning imaging technology of composite bonding structure is studied;Aiming at the interference problem of large amount of full matrix signal data,a linear low-pass filter based on least square method is designed.After data reconstruction,the effect of full matrix full focus imaging is improved;By quantifying the interfacial debonding defects,the effectiveness and accuracy of B-scan,fan scan and full focus imaging are analyzed.Experimental results show that ultrasonic phased array technology can detect the interface debonding of composite and cladding components efficiently and high quality,which provides a basis for industrial nondestructive testing of composite engine shell.