| The solid rocket motor(SRM)is widely used in modern missile weapon system because of its good maneuverability,simple structure,high reliability and easy to maintain.SRM shell for multi-layer bonded structure,the adhesive interface is easy to appear crack,debonding,defects such as inclusions,porosity and strength weakening,the poses a great threat to missile running safety,therefore carried out on the cohesive force of SRM shell structure of nondestructive testing theory and technology research is always the hot topic in both at home and abroad.Electromagnetic ultrasonic technology in testing when don't need a coupling agent,don't need to be on the surface of the metal material processing in advance,with high detection accuracy,high efficiency and low cost advantage,received wide attention of scholars both at home and abroad.This topic in the system,therefore,to study the electromagnetic ultrasonic testing technique,on the basis of basic theory and key technology,that is likely to affect the detection effect factors are analyzed in focus,and in view of the typical defects such as cracks,debonding launched a test,finally combined with infrared thermal imaging technology SRM shell bonding defects detection strategies are put forward.The content and innovative achievements of this paper mainly include the following aspects:(1)In-depth analysis of the electromagnetic ultrasonic technology detection mechanism.Based on the two mechanisms of lorentz force and magnetostrictive force,this paper analyzes the excitation,function and acceptance process of ultrasonic wave.But also make full use of the principle of acoustic impedance,reveals the defects in the ultrasonic reflection,transmission and reflection in structure when the propagation law,such as for the SRM electromagnetic ultrasonic flaw detection of laid the theoretical basis of the corresponding simulation and experiment.(2)The influence factor analysis of the detection of SRM shell bond structure by electromagnetic ultrasonic technology was carried out.On the modeling and simulation of the process in which the electromagnetic ultrasonic testing,mainly analyzes the wire properties(electrical conductivity,magnetic permeability,cross-sectional area,etc.)and specimen properties(resistivity,permeability,etc.)on the influence of electromagnetic ultrasonic acoustic conversion efficiency,and the introduction of SRM crack defects studied the distribution of magnetic field,the influence law of lorentz force,eddy current, and so on,to test the electromagnetic ultrasonic testing provides guidance mechanism,optimization of experimental design.(3)The systematic study on the electromagnetic ultrasonic testing of SRM typical defects was carried out.Design made two experimental specimens,one kind is the internal crack in SRM steel casing specimen,another kind is debonding flaws in SRM steel shell/thermal barrier structure specimen,by means of optimization of the electromagnetic ultrasonic testing technology to test the two kinds of specimens,using the test results of electromagnetic ultrasonic under the condition of different depth of defect detection ability were analyzed,and the numerical analysis results to verify the electromagnetic ultrasonic.This paper USES electromagnetic ultrasonic bonding structure of typical defects were tested on SRM shell,the integrated use of theoretical analysis,numerical simulation and the method of test,studied the key technology in the process of detection,and verifies the electromagnetic ultrasonic bonding technology in SRM shell structure in the process of testing the feasibility of the application,this to promote electromagnetic ultrasonic technology in the practical application in the field of aerospace has the very vital significance. |
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