Study On Several Typical Structures Of The Space Debris In Orbit Cognitive By Acoustic Emission Technology

Along with the space debris environment deteriorating,the manned spacecraft inorbit is become more and more dangerous.For real-time monitoring of space debrisimpacts on spacecraft events, people made a variety of on-orbit sensing technologysolutions.Among them, the use of acoustic emission technique for percussive impactevent source localization, some due to their inherent advantages gradually attention hasbeen paid and carried out relevant research. However, many manned spacecraftstructures, mainly flat, stiffened plate and weld plate containing such structure, andstructure size is relatively large, therefore, how the sensor by placing fewer, largerstructure to achieve different area within the acoustic emission source location, it hasbecome a hot and difficult problems.At present, the domestic flat by space debris impact for acoustic emission sourcelocation for a greater amount of research, and can more accurately within a certainrange to determine the impact source location, but due to size restrictions laboratoryequipment, yet the lack of long-range conditions Acoustic emission source localizationunder study. As the propagation distance increases, the acoustic emission signals platewave modes will change, which will determine the arrival time of the signal difficult;velocity may not be uniform, the selection will bring difficulties velocity; characterizedin amplitude appears greater attenuation threshold selection will locate difficult.Therefore, the need to study the plates in the more distant acoustic emission signalpropagation within and quantitative analysis of different parameters on thecharacteristics of effective positioning distance.For stiffened plate, there were only a few universities and research institutes byspace debris impact on its source localization techniques for a certain research, but thelack of quantitative conclusions. Since the existence of the body muscle, tendonacoustic emission signal through the body, the body and the tendons and tendon plateboundary interface occurs reflection, transmission and other phenomena, propagationof acoustic emission signal major changes will occur. Tendons body for acousticemission signals depends mainly on the impact of the structural parameters and bodymuscle tendons body number, therefore, need reinforcement body parameters onquantitative analysis of acoustic emission signal arrival time, velocity and amplitudeattenuation characteristics of the impact, and then analyzes their Acoustic emissionsource location of the effective positioning distance.For tablet containing a weld, the domestic impact of space debris on its subject positioning of acoustic emission sources less studied. As the weld material changes inacoustic emission signals have one medium into another medium occurs reflection,transmission phenomenon, the same arrival time will give the determination of velocitymeasurement and threshold selection difficult. Therefore, quantitative analysis of theweld material on the acoustic emission source location of the effective positioningdistance.In this context, this paper focuses manned spacecraft typical structure----plate,stiffened plates and plates with welds, the use of numerical simulation techniques wereused to obtain a flat, reinforced with weld plate and flat space debris hypervelocityimpact generated by the acoustic emission signals, respectively, analyzed thehigh-speed crash in which acoustic emission signal propagation and its perception ofspace debris in orbit effective positioning of acoustic emission source localizationdistance of.First, a more detailed analysis of the high-speed impact of acoustic emission signalpropagation in the plate. Using wavelet transform analysis of flat plate wave mode withthe variation of the propagation distance, using fast Fourier transform of the acousticemission frequency components obtained as the distance variation. Obtained undercertain conditions, apply to S0mode attenuation of the first peak of the mathematicalmodel that can be compared to the distance in a range suitable for S0modecharacteristic amplitude attenuation.Second, quantitative analysis of the impact of the tendon body acoustic emissionsignals for high-speed propagation effects. Tendons body stiffened plate S0mode onthe arrival time is not affected. The first peak on the S0mode will cause someattenuation, attenuation depends mainly on the number of rib width and rib body, butnot its proportional.Third, the analysis of the weld material on the acoustic emission signalpropagation effects. Weld material mainly S0mode generates a first peak is smallerimpact on the plate wave mode, the time domain waveform, S0mode has no effect onthe arrival time. Signal through the weld, the plate wave modal and modal characteristicparameters and the same working conditions, the situation did not pass weld is noessential difference, can be considered the weld on acoustic emission source location isnot greater impact.Finally, the stiffened panel acoustic emission source localization effectivelypositioning distance is analyzed. Specific structural parameters obtained efficientlystiffened plate positioning distance. This research further as space debris in orbit perception system of acousticemission sensors layout laid the technical foundation, has some theoretical significanceand engineering application value.