Study On Automatic Detection System For Insulating Layer Debonded-flaws Of SRM

In most cases, the structure of solid rocket motor(SRM) is composed of three interfaces which contains motor shell, insulating layer and propellant. The rockets'safely-launch and performances are directly affected by the situation of bonding between the shell and the insulating interface. Therefore, the study on the bonding quality detection for SRM has some practical value.This paper takes the SRM as research object and develops an automatic bonding quality detection system with certain universalities. Firstly, according to the processing features during the SRM producing, the ultrasonic based pulse-echo detection method by using immersion focusing probe is taken and a 2-DOF structure for different diameter motors'supporting is designed. The body's uniform velocity rotation cooperated by the probe's uniform velocity in-line feeding provides the frequency for the characteristic signals'collecting. The C-scan image based on the spiral scanning of the whole motor is presented.Secondly, in accordance with the features of the stripe noise in the C-scan image, a band-hinder filter on frequency is chosen. A short median filtering with a first order differential as a pretreatment method is propounded combined with the background noise's characteristics. The processing results demonstrate that the noise-abatements are effective and the features of the delamination flaws are well protected.Finally, On the basis of self-adaptive threshold segmentation and binarization for the scan image, an improved judgment method via taking the energy-summation in the area restricted by the threshold is proposed. The auto-testing results indicate that the system calculates the locations and the dimensions of artificial flaws relatively accurately. The processing methods are certificated and the system detection resolution reachesФ3mm.