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Cross-sectional area is an important parameter for spacecraft breakup debris as it is the directly measured data in space observation. It is significant for observing and analysing the spacecraft breakup event to accurately modelling the area distribution of the breakup debris. In this paper, experimental study has been performed on debris area distribution characteristics of spacecraft under hypervelocity impact. The tests are carried out at the ballistic ranges of CARDC. Aluminium projectiles are launched to normally impact the simulated spacecrafts at about 3.0 km/s. The simulated spacecrafts are made up of aluminium plates, filled with some simulated electronics boxes, each of which was installed with a circuit board. “Soft-catch” devices are used to recover the breakup fragments. The test results show that: 1) the relationship between the cross-sectional area and the characteristic length of debris, which can be obtained in the logarithmic coordinates by linear fitting, represents the debris shape characteristic in a certain extent; 2) the area-to-mass ratios of fragments show normal distributions in the logarithmic coordinates; 3) debris made of different materials can be distinguished by different peaks on the distribution curves; 4) the area-to-mass ratio distributions can be expressed by a linear superimposition of several normal functions which represent the main materials of the spacecraft. [ABSTRACT FROM AUTHOR]

Abstract Four kinds of aramid fibre and three compound modes of aramid with ceramic fibre were studied by hypervelocity impact tests respectively to probe the fabric layer with higher performance in space debris shield configuration. The aramid fibres include the Aramid-II manufactured in America, the Aramid-II, the Aramid-III and the PBO manufactured in China. Based on the above test results, the Aramid-III was chosen to compound with the basalt. The compound modes include hybrid weaving, affixing the Aramid-III and basalt fabric layers with the glue, and sewing them with the aramid thread. The configurations are impacted by the 5 mm-diameter Al projectile with the velocities of 4.5 km/s to 5.0 km/s. The test results show that the fabric layer containing Aramid-III fabric has equivalent shielding performance with the PBO fabric, and they are better than the other two stuffed layers containing Aramid-II fabric respectively under the equivalent areal density. The performance of stuffed layer is influenced by the adhesion degree of basalt and Aramid-III fibre. The three compound modes all improve the fabric adhesion degree, however, the over adhesion makes against dissipating the kinetic energy of debris cloud, which causes the performance to degrade. Highlights The influences of aramid fibre and its compound with ceramic on shielding performance are studied. The hybrid fabric is designed and woven to use as the stuffed layer. The stuffed fabric layers are tightened by the affixing glue and the sewing aramid thread. [ABSTRACT FROM AUTHOR]

In order to study the cracking and intercepting mechanism of stuffed layer configuration on the debris cloud and to develop stuffed layer configuration with better performance, the hypervelocity impact tests on shielding configurations with stuffed layer were carried out. Firstly, the hypervelocity impact tests on the shielding configuration with stuffed layer of 3 layer ceramic fibre and 3 layer aramid fibre were finished, the study results showed that the debris cloud generated by the aluminum sphere impacting bumper at the velocity of about 6.2 km/s would be racked and intercepted by the stuffed layer configuration efficiently when the ceramic fibre layers and aramid fibre layers were jointed together, however, the shielding performance would be declined when the ceramic fibre layers and aramid fibre layers were divided by some distance. The mechanism of stuffed layer racking and intercepting the debris cloud was analyzed according to the above test results. Secondly, based on the mechanism of the stuffed layer cracking and intercepint debirs cloud the hypervelocity impact tests on the following three stuffed layer structures with the equivalent areal density to the 1 mm-thick aluminum plate were also carried out to compare their performance of cracking and intercepting debris cloud. The mechanisms of stuffed layer racking and intercepting the debris cloud were validated by the test result. Thirdly, the influence of the stuffed layer position on the shielding performance was studied by the test, too. The test results would provide reference for the design of better performance shielding configuration with stuffed layer. [ABSTRACT FROM AUTHOR]

Based on the typical Whipple-type shield, a novel shield configuration with a front bumper of TiB 2 -based composite is designed in this paper, and the hypervelocity impact tests are conducted to compare the protection performance of this new composite bumper with that of the conventional aluminum bumper at the predicted impact velocities of about 3 km/s, 5 km/s and 7 km/s. The protection efficiency of different bumper materials is evaluated by the bumper perforation as well as the damage pattern of the rear wall and the witness plate. The postmortem observations of macroscopic and microscopic damage morphology reveal that the TiB 2 -based composite bumper can diminish the damage to the rear wall and exhibits better protective performance than the aluminum bumper, especially when the impact velocity reaches 5 km/s or more. Analyses of the shadowgraph of debris indicate that the kinetic energy of debris cloud is distributed among a large number of ultrafine particles, therefore, the well-fractured projectile fragment and widespread impact area can be taken as the main reasons for the better performance of TiB 2 -based composite bumpers. Besides, preliminary researches demonstrate some positive application of this new bumper material in protective systems for micrometeoroid and orbital debris shielding. [ABSTRACT FROM AUTHOR]

In an effort to find a lighter shield for shielding space debris impact, the wood stuffed shield was proposed in this paper based on the wood properties such as low density, low cost, high yield strength when the strain rate is high. Hypervelocity impact tests ( Ф  = 5.0 mm~ 8.0 mm, V  = 4.79 km/s ~ 7.24 km/s) were carried out to compare the shielding capabilities of the pinewood stuffed shield, aluminum triple-wall shield and Nextel/Kevlar fabric stuffed shield with the same areal density. Results show that, with the same areal density, the shielding capability of the wood stuffed shield is greater than that of the aluminum triple-wall shield and similar to that of Nextel/Kevlar fabric stuffed shield which is widely used on the spacecraft. To explore the reason why the shielding capability of the wood stuffed shield is effective relative to an aluminum triple-wall shield, SPH (smoothed particle hydrodynamic) simulations were carried out. [ABSTRACT FROM AUTHOR]

Eight hypervelocity impact tests of aluminum projectiles impacting aluminum plates were conducted using two-stage light gas gun. The diameters of projectile ranged from 2.0 mm to 5.0 mm, the impact velocities varied from 3.0 km/s to 6.0 km/s, and all tests were normal impacts. The time-integrated UV spectra of ejecta cloud were measured by use of a commercially spectrograph and an intensified charge-coupled device camera. Six aluminum peaks and two concomitant peaks were identified in the emission spectrum. Then the effects of the concomitant peaks were analyzed and decoupled. On the basis of spectral data, the ejecta cloud temperatures were analyzed using the Boltzmann diagram method. The effects of the uneven temperature distribution of ejecta cloud and radiation self-absorption on the measured results were discussed. It is found that self-absorption within the ejecta cloud is the predominant reason for the data points lying far from the fitting-line and should therefore be considered. Conversely, the uneven temperature distribution of the ejecta cloud is not found to significantly contribute to the fitting procedure. The temperature measured by Boltzmann diagram method is the excitation temperature. Moreover, it is found that the measurement result is the “average” temperature over both time and space, and the result tends to be shifted to the highest temperature of the ejecta cloud. [ABSTRACT FROM AUTHOR]

Spacecraft shields play an important role in shielding against the impact of space debris. Increasing the dispersion degree of the debris produced by the impact of the space debris on the bumper of configuration is able to lower the concentration of debris impacting on the rear plate and thus to reduce the risk of debris perforating the rear plate. In order to improve the dispersion degree, the N-shape configuration is proposed and studied by hypervelocity impact test with the velocity of 4.80 km/s and numerical simulation with the velocities ranging from 3.0 km/s to 7.0 km/s. As a comparison, the distribution of debris impacting on the rear plate is also investigated for the parallel triple-wall configuration with the same areal density. It is found that this degree is increased in the N-shape configuration due to the oblique plate, and therefore the risk of debris perforating the rear plate is reduced compared to the case of parallel triple-wall configuration. [ABSTRACT FROM AUTHOR]

Abstract: A series of numeric simulations for hypervelocity impact have been done at first. The work conditions are as follows: the material of the projectile and the target is 2A12, the impact velocity is 3–7 km/s, and the impact angle is 0°∼60°. Then the debris data identified by DebrisID program from numerical simulation results are analyzed. The model of debris cloud based on the statistical results is proposed, which includes five parts: the velocity of the debris cloud, the distribution functions of debris mass, velocity, space angles, and the relation of different distributions. A fast simulation method for debris cloud is developed at last, which is able to get detailed characteristic data of debris in short time. The debris cloud's image and characteristics agree well with results from numerical simulation and hypervelocity impact test. [Copyright &y& Elsevier]

Abstract: In this paper, the breadth first search algorithm and the convex hull solution of large-scale 3D/2D point set were used to directly obtain the fragment characteristics and distributions of the debris cloud produced in a hypervelocity impact, which was simulated by the smooth particle hydrodynamics (SPH) method. The computational method of debris identification and characteristic parameters recognizing from numerical simulation data produced by SPH method was developed. The numerical simulation was compared with test which was carried out at the ballistic range of CARDC (China Aerodynamics Research & Development Center). The fragment number and mass distribution obtained by the numerical calculation agree with those obtained from the test. The method developed in this paper can acquire the fragment characteristics and distributions from hypervelocity impact numerical simulation results, and can be used for data processing and damage analysis in numerical simulation of hypervelocity impact. [Copyright &y& Elsevier]

In order to improve the survivability of in-orbit spacecraft against the hypervelocity impact (HVI) of space debris, the lightweight B 4 C/Al composite is fabricated by the pressureless presintering and Al infiltration in vacuum and applied as the bumper of Whipple shield configuration. The HVI tests ranging from 3 km/s to 6.5 km/s are carried out to assess the shield performance of B 4 C/Al bumper. The fitting line of the ballistic limit for the B 4 C/Al bumper is obtained, and its critical projectile size can be improved by about 20% in comparison to the conventional Al alloy Whipple shield configuration. Based on the damage features of bumper and rear wall, the B 4 C ceramic phase of B 4 C/Al composite is the key reason to break the projectile into smaller fragments or liquid droplets of debris cloud. The Al plastic phase with three-dimensional network enhances the toughness of B 4 C/Al composite bumper, which plays an important role in avoiding structural failure caused by shock waves. Hence, the impact kinetic energy of debris cloud is obviously dispersed, and the subsequent impact damages on real wall are alleviated accordingly. The primary investigation provided theoretical and technical instructions for the design and application of B 4 C/Al composite in MMOD shield configuration. The impact crater microtopography on rear wall of B 4 C/Al bumper. Unlabelled Image • The light-weight B 4 C/Al composite material was prepared by the pressureless presintering and Al infiltration in vacuum. • The fitting ballistic limit line of Whipple configuration with B 4 C/Al bumper for 3 km/s–6.5 km/s HVI is obtained. • The B 4 C/Al bumper exhibits better shielding performance than Al bumper with same areal density in the HVI tests. • The HVI damage behavior of the bumper plate and the rear wall under different impact velocity is discussed. • The structural features and evolution of debris cloud of different bumper under different impact velocity is discussed. [ABSTRACT FROM AUTHOR]