It is widely known that the hypervelocity impact of orbital debris can cause serious damage to spacecraft,and enhancing the impact resistance is the great concern of spacecraft shield design.This paper provides a comp...It is widely known that the hypervelocity impact of orbital debris can cause serious damage to spacecraft,and enhancing the impact resistance is the great concern of spacecraft shield design.This paper provides a comprehensive overview of advances in the development of bumper materials for spacecraft shield applications.In particular,the protective mechanism and process of the bumper using different materials against hypervelocity impact are reviewed and discussed.The advantages and disadvantages of each material used in shield were discussed,and the performance under hypervelocity impact was given according to the specific configuration.This review provides the useful reference and basis for researchers and engineers to create bumper materials for spacecraft shield applications,and the contemporary challenges and future directions for bumper materials for spacecraft shield were presented.展开更多
An experimental system has been built to produce and measure the magnetic field in the backward ejected matter during hypervelocity impact. The designs of measurement system and coil, the choice of associated equipmen...An experimental system has been built to produce and measure the magnetic field in the backward ejected matter during hypervelocity impact. The designs of measurement system and coil, the choice of associated equipment, and the system calibration are also described in detail. The measurement of magnetic induction intensity for different given coil positions and azimuth angles are performed with two-stage light-gas gun. On condition that impact velocities are approximately equal and incidence angles are 45°, 60° and 90° respectively, the relationship between average magnetic induction intensity and impact angle at different time spans is obtained. Experimental results show that the average magnetic induction intensity with incidence angle of 90° is larger than those with incidence angles of 45°and 60°.展开更多
A fast-sweep Langmuir probe （FSLP） diagnostic system was designed and applied to obtain the electron temperature fluctuations of a transient plasma. The diagnostic system consists of a single Langmuir probe driven b...A fast-sweep Langmuir probe （FSLP） diagnostic system was designed and applied to obtain the electron temperature fluctuations of a transient plasma. The diagnostic system consists of a single Langmuir probe driven by a high frequency sinusoidal voltage. The current-voltage I- V characteristics can be recorded by sweeping the voltage and measuring the current with an appropriate circuit. This new instrument is based on a dual channel circuit that compensates for stray capacitance. The current and voltage spectra were acquired from the probe synchronously by a digital oscilloscope. The aim of this work was to apply the FSLP diagnostic system to a time- dependent plasma generated by a hypervelocity impact between the LY12 Aluminum projectile and LY12 Aluminum target.展开更多
Whipple shield,a dual-wall system,as well as its improved structures,is widely applied to defend the hypervelocity impact of space debris(projectile).This paper reviews the studies about the mechanism and process of p...Whipple shield,a dual-wall system,as well as its improved structures,is widely applied to defend the hypervelocity impact of space debris(projectile).This paper reviews the studies about the mechanism and process of protection against hypervelocity impacts using Whipple shield.Ground-based experiment and numerical simulation for hypervelocity impact and protection are introduced briefly.Three steps of the Whipple shield protection are discussed in order,including the interaction between the projectile and bumper,the movement and diffusion of the debris cloud,and the interaction between the debris cloud and rear plate.Potential improvements of the protection performance focusing on these three steps are presented.Representative works in the last decade are mentioned specifically.Some prospects and suggestions for future studies are put forward.展开更多
The structure of ultrafine grain is formed at the crater bottom of pure iron target under hypervelocity impact. The microstructures of different layers at the crater bottom were characterized by optical microscopy （O...The structure of ultrafine grain is formed at the crater bottom of pure iron target under hypervelocity impact. The microstructures of different layers at the crater bottom were characterized by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The cross-section observation was performed to reveal the grain refinement process driven by plastic deformation. Firstly, low energy dislocation structures （LEDS） such as dense dislocation walls （DDWs） and dislocation tangles （DTs） refine the original grains and form intersecting lamellar structures. With increasing strain, DDWs and DTs transform into subboundaries with small misorientations to separate lamellar structure to cells. Subboundaries are converted to high misorientation grain boundaries, so ultrafine grains are formed. The formation of ultrafine grains was discussed in the dynamic recrystallization process due to the large strain and strain rate induced by spherical shock wave.展开更多
Shock wave is emitted into the plate and sphere when a sphere hypervelocity impacts onto a thin plate.The fragmentation and phase change of the material caused by the propagation and unloading of shock wave could resu...Shock wave is emitted into the plate and sphere when a sphere hypervelocity impacts onto a thin plate.The fragmentation and phase change of the material caused by the propagation and unloading of shock wave could result in the formation of debris cloud eventually.Propagation models are deduced based on one-dimensional shock wave theory and the geometry of sphere,which uses elliptic equations(corresponding to ellipsoid equations in physical space)to describe the propagation of shock wave and the rarefaction wave.The“Effective thickness”is defined as the critical plate thickness that ensures the rarefaction wave overtake the shock wave at the back of the sphere.The“Effective thickness”is directly related to the form of the debris cloud.The relation of the“Effective thickness”and the“Optimum thickness”is also discussed.The impacts of Al spheres onto Al plates are simulated within SPH to verify the propagation models and associated theories.The results show that the wave fronts predicted by the propagation models are closer to the simulation result at higher impact velocity.The curvatures of the wave fronts decrease with the increase of impact velocities.The predicted“Effective thickness”is consistent with the simulation results.The analysis about the shock wave propagation and unloading in this paper can provide a new sight and inspiration for the quantitative study of hypervelocity impact and space debris protection.展开更多
We have for the first time elucidated the microstructural evolution and deformation behaviors of a gradient textured AZ31 B Mg alloy plate under the ultrahigh strain rate of ~10~6 s^(-1) that is generated by a two-sta...We have for the first time elucidated the microstructural evolution and deformation behaviors of a gradient textured AZ31 B Mg alloy plate under the ultrahigh strain rate of ~10~6 s^(-1) that is generated by a two-stage light gas gun with the hypervelocities of 1.6-4.4 km s^(-1). The hypervelocity impact cratering behaviors indicate that the cratering deformation of AZ31 B Mg alloy is mainly affected by the inertia and strength of the target material. The crater prediction equation of AZ31 B Mg alloy target under impact velocity of 5 km s^(-1) is given. The 2017 Al projectile completely melts in the Mg alloy target plate at the impact velocities of 3.8 km s^(-1) and 4.4 km s^(-1), and the microstructural evolution around the crater is: dynamic recrystallization zone, high-density twinning zone, low-density twinning zone, and Mg alloy matrix. It is found that the dynamic recrystallization, twinning and cracking are the main deformation behaviors for the AZ31 B Mg alloy to absorb the shock wave energy and release the stress generated by the hypervelocity impact. The main plastic deformation mechanisms of the Mg alloy target during hypervelocity impact are twinning and dislocation slip. Microstructure analysis shows the interactions of twins-twins, dislocations-dislocations, and twins-dislocations determine the strain hardening during the hypervelocity impact process, which eventually contributes the dynamic mechanical properties. The evolution of microhardness around the crater further demonstrates the microstructural evolutions and their interactions under the hypervelocity impacts.展开更多
In this study,a series of hypervelocity impact tests were carried out based on a two-stage light gas gun,and the sequence spectrum and radiation evolution data of the impact products under different impact conditions ...In this study,a series of hypervelocity impact tests were carried out based on a two-stage light gas gun,and the sequence spectrum and radiation evolution data of the impact products under different impact conditions were obtained.The diameter of the projectile is 3-5 mm,the impact velocity is 3.13-6.58 km/s,and the chamber pressure is 0.56-990 Pa.The spectrum of ejected debris cloud in the 250-310 nm band were obtained using a transient spectral measurement system and a multi-channel radiometer measurement system.The test results reveal that the flash radiation intensity increases as a power function with the kinetic energy of the impact.Furthermore,the peak value of the line spectrum decreases as the chamber vacuum degree increases,while the radiation width gradually expands.The line spectrum in the spectral characterization curve corresponds to the ejected debris clouds splitting phase,which does not produce significant line spectrum during material fragmentation and is dominated by the continuum spectrum produced by blackbody radiation.There will appear one or three characteristic peaks in the flash radiation time curve,the first and second peaks correspond to the penetration phase and the third peak corresponds to the expansion phase of the ejected debris clouds on the time scale,the first and second peaks are more sensitive to the chamber vacuum degree,and when the pressure is higher than 99 Pa,the first and second characteristic peaks will disappear.The radiant heat attenuation of the flash under different impact conditions is significantly different,the attenuation exponent has a power function relationship with the impact velocity and the chamber vacuum degree,while the attenuation exponent has a linear relationship with the diameter of the projectile,the specific expression of the attenuation exponent is obtained by fitting.The findings from this research can serve as a valuable reference for remote diagnostic technologies based on flash radiation characteristics.展开更多
Two techniques are applied to diagnose characteristic parameters of plasma created by hypervelocity impact, such as electron temperature and electron density. The first technique is a sweep Langmuir probe （SLP）, whi...Two techniques are applied to diagnose characteristic parameters of plasma created by hypervelocity impact, such as electron temperature and electron density. The first technique is a sweep Langmuir probe （SLP）, which is a new apparatus based on a dual channel circuit that can compensate for stray capacitance and obtain a good synchronicity, so that electrostatic turbulence with a good temporal resolution can be acquired. The second technique is a triple Langmuir probe （TLP）, which is an electrostatic triple Langmuir probe diagnostic system, in which no voltage and frequency sweep is required. This technique allows to measure electron temperature, electron density as a function of time. Moreover, the triple Langmuir probe diagnostic system allows the direct display of electron temperature and semidirect display of electron density by an appropriate display system, the system permits us to eliminate almost all data processing procedures. SLP and TLP were applied to obtain fluctuations of the characteristic parameters of plasma generated by hypervelocity impact. As an example of their application to time-dependent plasma measure- ment, the electron temperature and electron density of plasmas were acquired in hypervelocity impact experiments. Characteristic parameters of plasma generated by hypervelocity impact were compared by the two kinds of diagnostic techniques mentioned above.展开更多
The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical simulation.By comparing the computation resul...The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical simulation.By comparing the computation results with the experimental results,the correctness of the calculation and the statistical method of momentum transfer coefficient is verified.Different shapes of aluminum,copper and heavy tungsten alloy projectiles striking aluminum,basalt,and pumice target for impacts up to 10 km/s are simulated.The influence mechanism of the shape of the projectile and projectile/target density on the momentum transfer was obtained.With an increase in projectile density and length-diameter ratio,the energy transfer time between the projectile and targets is prolonged.The projectile decelerates slowly,resulting in a larger cratering depth.The energy consumed by the projectile in the excavation stage increased,resulting in lower mass-velocity of ejecta and momentum transfer coefficient.The numerical simulation results demonstrated that for different projectile/target combinations,the higher the wave impedance of the projectile,the higher the initial phase transition velocity and the smaller the mass of phase transition.The results can provide theoretical guidance for kinetic impactor design and material selection.展开更多
Dual-plate structure is very effective in the protection of space vehicle from hypervelocity im- pact.The experiments of A1 projectile impacting A1 dual targets at the velocity ranging over 2.5—7.0 km/s were systemat...Dual-plate structure is very effective in the protection of space vehicle from hypervelocity im- pact.The experiments of A1 projectile impacting A1 dual targets at the velocity ranging over 2.5—7.0 km/s were systematically conducted.The damage effects were examined,including the perforation of the shield, the development of debris cloud and the general damage characteristics of the subplate.Many valuable experi- mental data and phenomena have been obtained展开更多
Speculation that elliptical to circular segments of surface exposed lithospheric mantle belts might mark rims of large terrestrial impact basins suggests that the ophiolite rimmed Sulu Sea, Loyalty and Yucatan basins ...Speculation that elliptical to circular segments of surface exposed lithospheric mantle belts might mark rims of large terrestrial impact basins suggests that the ophiolite rimmed Sulu Sea, Loyalty and Yucatan basins may have resulted from middle Miocene, late Eocene and K-Pg boundary mantle excavating hypervelocity impacts on Earth(Olds, 2019). The Semail ophiolite suggests such a circular rim segment with a ~250 km radius of curvature implying an originally ~500 km diameter impact basin before subsequent deformation/destruction at plate boundaries. Presently the Arabian plate is being actively consumed at the Makran subduction zone(Penney et al., 2017) which evidently will result in subduction of the Gulf of Oman and suturing of the adjacent Semail ophiolite in the near geological future. For large impact basins on the rocky planets, O’Keefe and Ahrens(1993) estimate maximum excavation depth to be roughly 5% of final crater diameter. In this case maximum ejecta source depths of ~25 km are implied, a number roughly comparable with observed thicknesses of crust plus mantle sections for the Semail ophiolite(Aldega et al., 2017) and depths of burial due to over-thrusting(obduction) implied by the exhumed metamorphic sole(Cowan et al., 2014). Hacker et al.(1996) and Roberts et al.(2016) place peak metamorphism timing of the Semail metamorphic sole within uncertainty of the C-T Boundary at 94 Ma. Study of possible correlation of peak obduction timing with end-Cenomanian global extinction plus anoxic events(Wan et al., 2003) and C-T boundary impact ejecta plus tsunami deposits(Monteiro et al., 2001) may be warranted.展开更多
This article addresses the response of GLAss fiber REinforced aluminum to hypervelocity impacts of micrometeoroid analogs at impact velocities of 7 km/s and beyond.In relation,the damage modes of different GLAss fiber...This article addresses the response of GLAss fiber REinforced aluminum to hypervelocity impacts of micrometeoroid analogs at impact velocities of 7 km/s and beyond.In relation,the damage modes of different GLAss fiber REinforced aluminum configurations have been exemplified.The GLAss fiber REinforced aluminum configurations comprised six to twelve variably thick aluminum layers and up to four plies of glass fiber reinforced epoxy per composite laminate.Hypervelocity impact experiments have been conducted with the help of a two-stage light-gas gun,wherein aluminum-and stainless steel projectiles were launched at velocities up to 7.15 km/s.Visual inspection of the damage area suggested the dissipation of impact energy in elastic-plastic deformation,petalling,delamination,debonding,tensile failure of fibers,and pyrolysis of epoxy.A prevailing damage mode was not apparent albeit.The quasi-isotropic ply orientation of S2-glass/FM94-epoxy laminates promoted the interference of shockand rarefaction waves and suppressed the damage area of GLAss fiber REinforced aluminum.To discriminate between the impact performance of different GLAss fiber REinforced aluminum configurations,the energy dissipated in different damage modes of GLAss fiber REinforced aluminum has been assessed quantitatively.In terms of normalized energy,the cross-ply GLAss fiber REinforced aluminum dissipated higher energy in petal formation than in other primary damage modes.The normalized petalling energy was found to decline with the increase of impact energy.The outcomes of this study will help to optimize the GLAss fiber REinforced aluminum laminate,which will be employed as a bumper shield to prevent the fatal damage and the unzipping of a spacecraft pressure bulkhead.展开更多
The primary causes of satellite breakups are hypervelocity impact and explosion,the research on satellite breakup can be used not only to evaluate the influence of breakup event on the space environment,but also to tr...The primary causes of satellite breakups are hypervelocity impact and explosion,the research on satellite breakup can be used not only to evaluate the influence of breakup event on the space environment,but also to trace whether the satellite has been deliberately attacked.It is of great significance in both civil and military aspects.The study of satellite breakup behaviors and model is reviewed to summarize the research progress and insufficiency in recent decades,including the satellite breakup experiment,measurement and characterization of fragments,distribution characteristics of breakup fragments,satellite breakup model,etc.The classical studies are introduced in detail,and the limitations of the current research are pointed out.According to the current research results,the contemporary challenges and future directions for satellite breakup study are presented.The research on satellite breakup is developing in two directions:the miniaturization of satellite size and the complexity of satellite component.The study on satellite breakup needs to be explored and deepened on improving the experimental launch speed,expanding the model application range and breakup revealing the results under combined effect of impact and explosion.展开更多
The smooth particle hydrodynamics (SPH) method is a very important tool to resolve hypervelocity problems. The basic principle of SPH method and how to generate a proper SPH mesh is described. The results of SPH simul...The smooth particle hydrodynamics (SPH) method is a very important tool to resolve hypervelocity problems. The basic principle of SPH method and how to generate a proper SPH mesh is described. The results of SPH simulations of hypervelocity impacts on thin or thick aluminum plates, performed by using the LS-DYNA 3D computer code, are also reported. The forming process and composition of the debris clouds simulated are identical with the experiment results. It can be concluded that the simulation is reasonable and SPH method is an ideal method for hypervelocity impact simulation..展开更多
Ground-based tests are important for studying hypervelocity impact(HVI)damage to spacecraft pressure vessels in the orbital debris environment.We analyzed the damage to composite overwrapped pressure vessels(COPVs)in ...Ground-based tests are important for studying hypervelocity impact(HVI)damage to spacecraft pressure vessels in the orbital debris environment.We analyzed the damage to composite overwrapped pressure vessels(COPVs)in the HVI tests and classified the damage into non-catastrophic damage and catastrophic damage.We proposed a numerical simulation method to further study non-catastrophic damage and revealed the characteristics and mechanisms of non-catastrophic damage affected by impact conditions and internal pressures.The fragments of the catastrophically damaged COPVs were collected after the tests.The crack distribution and propagation process of the catastrophic ruptures of the COPVs were analyzed.Our findings contribute to understanding the damage characteristics and mechanisms of COPVs by HVIs.展开更多
Polyimide is a typical complex high-molecular polymer of imide monomers,which is widely used in the manufacture of parts for aerospace engineering.The hypervelocity impacts between the spacecraft and orbital debris ca...Polyimide is a typical complex high-molecular polymer of imide monomers,which is widely used in the manufacture of parts for aerospace engineering.The hypervelocity impacts between the spacecraft and orbital debris can induce great damage to the spacecraft.In order to improve the safety of spacecraft,the characteristics of polyimide debris clouds produced by hypervelocity impact should be studied.Firstly,a Mie-Grüneisen equation of state based on the shock adiabat for polyimide,which describes the mechanical behavior in the numerical simulation,was obtained from hypervelocity impact experiments,then a 3-dimentional smoothed particle hydrodynamics program was compiled to numerically simulate the hypervelocity impact between aluminum projectiles(orbital debris)and polyimide targets with different impact velocities(3.km/s,5.km/s,8.km/s)and angles(0°,30°,45°,60°),finally typical shapes of debris clouds produced in different impact velocities and angles were collected from simulation results,the characteristics of which were systemically discussed.展开更多
The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate b...The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate because of dynamic shear failure and extrusion.A new empirical model was presented to predict the perforation diameter in thin plates impacted by high-velocity cylindrical projectiles.The fitting coefficients resulted in a root-mean-square of 0.0641 and a correlation coefficient of 0.991.The errors between the predicted and the experimental values were less than 7.251%,and less than 4.705%for 93.333%cases of the dataset.The accuracy of the proposed model is much higher than that of Hill's model.Compared with historical equations,the new model is more accurate and can well describe the variations of different parameters with the normalized penetrated hole.The model takes into account the strength of materials,which contributes to the excellent results.This paper could provide important theoretical support for the analysis of the perforation process and its mechanism.展开更多
To researching the damage characteristics of typical logical chip modules in spacecraft due to plasma generated by hypervelocity impacts,we have established a triple Langmuir probe diagnostic system and a logical chip...To researching the damage characteristics of typical logical chip modules in spacecraft due to plasma generated by hypervelocity impacts,we have established a triple Langmuir probe diagnostic system and a logical chips measurement system,which were used to diagnose plasma characteristic parameters and the logical chip module＇s logical state changes due to the plasma created by a 7075 aluminum projectile hypervelocity impact on the 2A12 aluminum target.Three sets of experiments were performed with the collision speeds of 2.85 km/s,3.1 km/s and2.20 km/s,at the same incident angles of 30 degrees and logical chip module＇s positions by using a two-stage light gas gun loading system,a plasma characteristic parameters diagnostic system and a logical chip module＇s logical state measurement system,respectively.Electron temperature and density were measured at given position and azimuth,and damage estimation was performed for the logical chip module by using the data acquisition system.Experimental results showed that temporary damage could be induced on logical chip modules in spacecraft by plasma generated by hypervelocity impacts under the given experimental conditions and the sensors＇ position and azimuth.展开更多
All long-duration spacecraft in low-earth-orbit are subject to high velocity impacts by meteoroids and space debris. Such impacts are expected to occur at non-normal incidence angles and can cause severe damage to the...All long-duration spacecraft in low-earth-orbit are subject to high velocity impacts by meteoroids and space debris. Such impacts are expected to occur at non-normal incidence angles and can cause severe damage to the spacecraft and its external flight-critical systems and possibly lead to catastrophic failure of the spacecraft. In order to ensure crew safety and proper function of internal and external spacecraft systems, the characteristics of a debris cloud generated by such impacts must be known. An analytical model is therefore developed for the characterization of the penetration and ricochet debris clouds created by the hypervelocity impact of an aluminum spherical projectile on an aluminum plate. This model employs normal and oblique shock wave theory to characterize the penetration and ricochet processes. The prediction results of center-of-mass trajectory and leading velocity of penetration and ricochet debris clouds are obtained and compared with numerical and experimental results in figures.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.12202068,12202087)China National Space Administration Preliminary Research Project(Grant Nos.KJSP2023020201,KJSP2020010402).
文摘It is widely known that the hypervelocity impact of orbital debris can cause serious damage to spacecraft,and enhancing the impact resistance is the great concern of spacecraft shield design.This paper provides a comprehensive overview of advances in the development of bumper materials for spacecraft shield applications.In particular,the protective mechanism and process of the bumper using different materials against hypervelocity impact are reviewed and discussed.The advantages and disadvantages of each material used in shield were discussed,and the performance under hypervelocity impact was given according to the specific configuration.This review provides the useful reference and basis for researchers and engineers to create bumper materials for spacecraft shield applications,and the contemporary challenges and future directions for bumper materials for spacecraft shield were presented.
基金National Natural Science Foundation of China (10772028)Talent Resources Development Special Funds of Shenyang (20081400103009)Doctoral Initiation Special Fund of Shenyang Ligong University
文摘An experimental system has been built to produce and measure the magnetic field in the backward ejected matter during hypervelocity impact. The designs of measurement system and coil, the choice of associated equipment, and the system calibration are also described in detail. The measurement of magnetic induction intensity for different given coil positions and azimuth angles are performed with two-stage light-gas gun. On condition that impact velocities are approximately equal and incidence angles are 45°, 60° and 90° respectively, the relationship between average magnetic induction intensity and impact angle at different time spans is obtained. Experimental results show that the average magnetic induction intensity with incidence angle of 90° is larger than those with incidence angles of 45°and 60°.
基金National Natural Science Foundation of China(No.10772028)
文摘A fast-sweep Langmuir probe （FSLP） diagnostic system was designed and applied to obtain the electron temperature fluctuations of a transient plasma. The diagnostic system consists of a single Langmuir probe driven by a high frequency sinusoidal voltage. The current-voltage I- V characteristics can be recorded by sweeping the voltage and measuring the current with an appropriate circuit. This new instrument is based on a dual channel circuit that compensates for stray capacitance. The current and voltage spectra were acquired from the probe synchronously by a digital oscilloscope. The aim of this work was to apply the FSLP diagnostic system to a time- dependent plasma generated by a hypervelocity impact between the LY12 Aluminum projectile and LY12 Aluminum target.
基金This work is supported by the National Natural Science Foundation of China(11627901,11872118).
文摘Whipple shield,a dual-wall system,as well as its improved structures,is widely applied to defend the hypervelocity impact of space debris(projectile).This paper reviews the studies about the mechanism and process of protection against hypervelocity impacts using Whipple shield.Ground-based experiment and numerical simulation for hypervelocity impact and protection are introduced briefly.Three steps of the Whipple shield protection are discussed in order,including the interaction between the projectile and bumper,the movement and diffusion of the debris cloud,and the interaction between the debris cloud and rear plate.Potential improvements of the protection performance focusing on these three steps are presented.Representative works in the last decade are mentioned specifically.Some prospects and suggestions for future studies are put forward.
文摘The structure of ultrafine grain is formed at the crater bottom of pure iron target under hypervelocity impact. The microstructures of different layers at the crater bottom were characterized by optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The cross-section observation was performed to reveal the grain refinement process driven by plastic deformation. Firstly, low energy dislocation structures （LEDS） such as dense dislocation walls （DDWs） and dislocation tangles （DTs） refine the original grains and form intersecting lamellar structures. With increasing strain, DDWs and DTs transform into subboundaries with small misorientations to separate lamellar structure to cells. Subboundaries are converted to high misorientation grain boundaries, so ultrafine grains are formed. The formation of ultrafine grains was discussed in the dynamic recrystallization process due to the large strain and strain rate induced by spherical shock wave.
基金supported by the National Natural Science Foundation of China(11627901,11872118).
文摘Shock wave is emitted into the plate and sphere when a sphere hypervelocity impacts onto a thin plate.The fragmentation and phase change of the material caused by the propagation and unloading of shock wave could result in the formation of debris cloud eventually.Propagation models are deduced based on one-dimensional shock wave theory and the geometry of sphere,which uses elliptic equations(corresponding to ellipsoid equations in physical space)to describe the propagation of shock wave and the rarefaction wave.The“Effective thickness”is defined as the critical plate thickness that ensures the rarefaction wave overtake the shock wave at the back of the sphere.The“Effective thickness”is directly related to the form of the debris cloud.The relation of the“Effective thickness”and the“Optimum thickness”is also discussed.The impacts of Al spheres onto Al plates are simulated within SPH to verify the propagation models and associated theories.The results show that the wave fronts predicted by the propagation models are closer to the simulation result at higher impact velocity.The curvatures of the wave fronts decrease with the increase of impact velocities.The predicted“Effective thickness”is consistent with the simulation results.The analysis about the shock wave propagation and unloading in this paper can provide a new sight and inspiration for the quantitative study of hypervelocity impact and space debris protection.
基金support from the Chongqing University Program (No.02090011044158)。
文摘We have for the first time elucidated the microstructural evolution and deformation behaviors of a gradient textured AZ31 B Mg alloy plate under the ultrahigh strain rate of ~10~6 s^(-1) that is generated by a two-stage light gas gun with the hypervelocities of 1.6-4.4 km s^(-1). The hypervelocity impact cratering behaviors indicate that the cratering deformation of AZ31 B Mg alloy is mainly affected by the inertia and strength of the target material. The crater prediction equation of AZ31 B Mg alloy target under impact velocity of 5 km s^(-1) is given. The 2017 Al projectile completely melts in the Mg alloy target plate at the impact velocities of 3.8 km s^(-1) and 4.4 km s^(-1), and the microstructural evolution around the crater is: dynamic recrystallization zone, high-density twinning zone, low-density twinning zone, and Mg alloy matrix. It is found that the dynamic recrystallization, twinning and cracking are the main deformation behaviors for the AZ31 B Mg alloy to absorb the shock wave energy and release the stress generated by the hypervelocity impact. The main plastic deformation mechanisms of the Mg alloy target during hypervelocity impact are twinning and dislocation slip. Microstructure analysis shows the interactions of twins-twins, dislocations-dislocations, and twins-dislocations determine the strain hardening during the hypervelocity impact process, which eventually contributes the dynamic mechanical properties. The evolution of microhardness around the crater further demonstrates the microstructural evolutions and their interactions under the hypervelocity impacts.
基金supported by the National Natural Science Foundation of China (Grant No.11672278)。
文摘In this study,a series of hypervelocity impact tests were carried out based on a two-stage light gas gun,and the sequence spectrum and radiation evolution data of the impact products under different impact conditions were obtained.The diameter of the projectile is 3-5 mm,the impact velocity is 3.13-6.58 km/s,and the chamber pressure is 0.56-990 Pa.The spectrum of ejected debris cloud in the 250-310 nm band were obtained using a transient spectral measurement system and a multi-channel radiometer measurement system.The test results reveal that the flash radiation intensity increases as a power function with the kinetic energy of the impact.Furthermore,the peak value of the line spectrum decreases as the chamber vacuum degree increases,while the radiation width gradually expands.The line spectrum in the spectral characterization curve corresponds to the ejected debris clouds splitting phase,which does not produce significant line spectrum during material fragmentation and is dominated by the continuum spectrum produced by blackbody radiation.There will appear one or three characteristic peaks in the flash radiation time curve,the first and second peaks correspond to the penetration phase and the third peak corresponds to the expansion phase of the ejected debris clouds on the time scale,the first and second peaks are more sensitive to the chamber vacuum degree,and when the pressure is higher than 99 Pa,the first and second characteristic peaks will disappear.The radiant heat attenuation of the flash under different impact conditions is significantly different,the attenuation exponent has a power function relationship with the impact velocity and the chamber vacuum degree,while the attenuation exponent has a linear relationship with the diameter of the projectile,the specific expression of the attenuation exponent is obtained by fitting.The findings from this research can serve as a valuable reference for remote diagnostic technologies based on flash radiation characteristics.
基金supported by National Natural Science Foundation of China(No.10972145)
文摘Two techniques are applied to diagnose characteristic parameters of plasma created by hypervelocity impact, such as electron temperature and electron density. The first technique is a sweep Langmuir probe （SLP）, which is a new apparatus based on a dual channel circuit that can compensate for stray capacitance and obtain a good synchronicity, so that electrostatic turbulence with a good temporal resolution can be acquired. The second technique is a triple Langmuir probe （TLP）, which is an electrostatic triple Langmuir probe diagnostic system, in which no voltage and frequency sweep is required. This technique allows to measure electron temperature, electron density as a function of time. Moreover, the triple Langmuir probe diagnostic system allows the direct display of electron temperature and semidirect display of electron density by an appropriate display system, the system permits us to eliminate almost all data processing procedures. SLP and TLP were applied to obtain fluctuations of the characteristic parameters of plasma generated by hypervelocity impact. As an example of their application to time-dependent plasma measure- ment, the electron temperature and electron density of plasmas were acquired in hypervelocity impact experiments. Characteristic parameters of plasma generated by hypervelocity impact were compared by the two kinds of diagnostic techniques mentioned above.
基金the National Natural Science Foundation of China(Grant Nos.62227901,12202068)the Civil Aerospace Pre-research Project(Grant No.D020304).
文摘The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical simulation.By comparing the computation results with the experimental results,the correctness of the calculation and the statistical method of momentum transfer coefficient is verified.Different shapes of aluminum,copper and heavy tungsten alloy projectiles striking aluminum,basalt,and pumice target for impacts up to 10 km/s are simulated.The influence mechanism of the shape of the projectile and projectile/target density on the momentum transfer was obtained.With an increase in projectile density and length-diameter ratio,the energy transfer time between the projectile and targets is prolonged.The projectile decelerates slowly,resulting in a larger cratering depth.The energy consumed by the projectile in the excavation stage increased,resulting in lower mass-velocity of ejecta and momentum transfer coefficient.The numerical simulation results demonstrated that for different projectile/target combinations,the higher the wave impedance of the projectile,the higher the initial phase transition velocity and the smaller the mass of phase transition.The results can provide theoretical guidance for kinetic impactor design and material selection.
文摘Dual-plate structure is very effective in the protection of space vehicle from hypervelocity im- pact.The experiments of A1 projectile impacting A1 dual targets at the velocity ranging over 2.5—7.0 km/s were systematically conducted.The damage effects were examined,including the perforation of the shield, the development of debris cloud and the general damage characteristics of the subplate.Many valuable experi- mental data and phenomena have been obtained
文摘Speculation that elliptical to circular segments of surface exposed lithospheric mantle belts might mark rims of large terrestrial impact basins suggests that the ophiolite rimmed Sulu Sea, Loyalty and Yucatan basins may have resulted from middle Miocene, late Eocene and K-Pg boundary mantle excavating hypervelocity impacts on Earth(Olds, 2019). The Semail ophiolite suggests such a circular rim segment with a ~250 km radius of curvature implying an originally ~500 km diameter impact basin before subsequent deformation/destruction at plate boundaries. Presently the Arabian plate is being actively consumed at the Makran subduction zone(Penney et al., 2017) which evidently will result in subduction of the Gulf of Oman and suturing of the adjacent Semail ophiolite in the near geological future. For large impact basins on the rocky planets, O’Keefe and Ahrens(1993) estimate maximum excavation depth to be roughly 5% of final crater diameter. In this case maximum ejecta source depths of ~25 km are implied, a number roughly comparable with observed thicknesses of crust plus mantle sections for the Semail ophiolite(Aldega et al., 2017) and depths of burial due to over-thrusting(obduction) implied by the exhumed metamorphic sole(Cowan et al., 2014). Hacker et al.(1996) and Roberts et al.(2016) place peak metamorphism timing of the Semail metamorphic sole within uncertainty of the C-T Boundary at 94 Ma. Study of possible correlation of peak obduction timing with end-Cenomanian global extinction plus anoxic events(Wan et al., 2003) and C-T boundary impact ejecta plus tsunami deposits(Monteiro et al., 2001) may be warranted.
基金funded by Bangladesh Air Force (BAF) Academy,Bangladesh
文摘This article addresses the response of GLAss fiber REinforced aluminum to hypervelocity impacts of micrometeoroid analogs at impact velocities of 7 km/s and beyond.In relation,the damage modes of different GLAss fiber REinforced aluminum configurations have been exemplified.The GLAss fiber REinforced aluminum configurations comprised six to twelve variably thick aluminum layers and up to four plies of glass fiber reinforced epoxy per composite laminate.Hypervelocity impact experiments have been conducted with the help of a two-stage light-gas gun,wherein aluminum-and stainless steel projectiles were launched at velocities up to 7.15 km/s.Visual inspection of the damage area suggested the dissipation of impact energy in elastic-plastic deformation,petalling,delamination,debonding,tensile failure of fibers,and pyrolysis of epoxy.A prevailing damage mode was not apparent albeit.The quasi-isotropic ply orientation of S2-glass/FM94-epoxy laminates promoted the interference of shockand rarefaction waves and suppressed the damage area of GLAss fiber REinforced aluminum.To discriminate between the impact performance of different GLAss fiber REinforced aluminum configurations,the energy dissipated in different damage modes of GLAss fiber REinforced aluminum has been assessed quantitatively.In terms of normalized energy,the cross-ply GLAss fiber REinforced aluminum dissipated higher energy in petal formation than in other primary damage modes.The normalized petalling energy was found to decline with the increase of impact energy.The outcomes of this study will help to optimize the GLAss fiber REinforced aluminum laminate,which will be employed as a bumper shield to prevent the fatal damage and the unzipping of a spacecraft pressure bulkhead.
基金supported by National Defense Science and Technology Program(A14007)China National Space Administration Preliminary Research Project(KJSP2020020101,KJSP2020010304)。
文摘The primary causes of satellite breakups are hypervelocity impact and explosion,the research on satellite breakup can be used not only to evaluate the influence of breakup event on the space environment,but also to trace whether the satellite has been deliberately attacked.It is of great significance in both civil and military aspects.The study of satellite breakup behaviors and model is reviewed to summarize the research progress and insufficiency in recent decades,including the satellite breakup experiment,measurement and characterization of fragments,distribution characteristics of breakup fragments,satellite breakup model,etc.The classical studies are introduced in detail,and the limitations of the current research are pointed out.According to the current research results,the contemporary challenges and future directions for satellite breakup study are presented.The research on satellite breakup is developing in two directions:the miniaturization of satellite size and the complexity of satellite component.The study on satellite breakup needs to be explored and deepened on improving the experimental launch speed,expanding the model application range and breakup revealing the results under combined effect of impact and explosion.
文摘The smooth particle hydrodynamics (SPH) method is a very important tool to resolve hypervelocity problems. The basic principle of SPH method and how to generate a proper SPH mesh is described. The results of SPH simulations of hypervelocity impacts on thin or thick aluminum plates, performed by using the LS-DYNA 3D computer code, are also reported. The forming process and composition of the debris clouds simulated are identical with the experiment results. It can be concluded that the simulation is reasonable and SPH method is an ideal method for hypervelocity impact simulation..
基金supported by the National Natural Science Foundation of China(Grant Nos.11672097,11772113)。
文摘Ground-based tests are important for studying hypervelocity impact(HVI)damage to spacecraft pressure vessels in the orbital debris environment.We analyzed the damage to composite overwrapped pressure vessels(COPVs)in the HVI tests and classified the damage into non-catastrophic damage and catastrophic damage.We proposed a numerical simulation method to further study non-catastrophic damage and revealed the characteristics and mechanisms of non-catastrophic damage affected by impact conditions and internal pressures.The fragments of the catastrophically damaged COPVs were collected after the tests.The crack distribution and propagation process of the catastrophic ruptures of the COPVs were analyzed.Our findings contribute to understanding the damage characteristics and mechanisms of COPVs by HVIs.
文摘Polyimide is a typical complex high-molecular polymer of imide monomers,which is widely used in the manufacture of parts for aerospace engineering.The hypervelocity impacts between the spacecraft and orbital debris can induce great damage to the spacecraft.In order to improve the safety of spacecraft,the characteristics of polyimide debris clouds produced by hypervelocity impact should be studied.Firstly,a Mie-Grüneisen equation of state based on the shock adiabat for polyimide,which describes the mechanical behavior in the numerical simulation,was obtained from hypervelocity impact experiments,then a 3-dimentional smoothed particle hydrodynamics program was compiled to numerically simulate the hypervelocity impact between aluminum projectiles(orbital debris)and polyimide targets with different impact velocities(3.km/s,5.km/s,8.km/s)and angles(0°,30°,45°,60°),finally typical shapes of debris clouds produced in different impact velocities and angles were collected from simulation results,the characteristics of which were systemically discussed.
基金supported by the National Natural Science Foundation of China(No.11772269).
文摘The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate because of dynamic shear failure and extrusion.A new empirical model was presented to predict the perforation diameter in thin plates impacted by high-velocity cylindrical projectiles.The fitting coefficients resulted in a root-mean-square of 0.0641 and a correlation coefficient of 0.991.The errors between the predicted and the experimental values were less than 7.251%,and less than 4.705%for 93.333%cases of the dataset.The accuracy of the proposed model is much higher than that of Hill's model.Compared with historical equations,the new model is more accurate and can well describe the variations of different parameters with the normalized penetrated hole.The model takes into account the strength of materials,which contributes to the excellent results.This paper could provide important theoretical support for the analysis of the perforation process and its mechanism.
基金supported by National Natural Science Foundation of China(Nos.10972145,11272218,11472178)Program for Liaoning Excellent Talents in University of China(No.LR2013008)Open Foundation of Key Laboratory of Liaoning Weapon Science and Technology,Liaoning Province Talents Engineering Projects of China(No.2012921044)
文摘To researching the damage characteristics of typical logical chip modules in spacecraft due to plasma generated by hypervelocity impacts,we have established a triple Langmuir probe diagnostic system and a logical chips measurement system,which were used to diagnose plasma characteristic parameters and the logical chip module＇s logical state changes due to the plasma created by a 7075 aluminum projectile hypervelocity impact on the 2A12 aluminum target.Three sets of experiments were performed with the collision speeds of 2.85 km/s,3.1 km/s and2.20 km/s,at the same incident angles of 30 degrees and logical chip module＇s positions by using a two-stage light gas gun loading system,a plasma characteristic parameters diagnostic system and a logical chip module＇s logical state measurement system,respectively.Electron temperature and density were measured at given position and azimuth,and damage estimation was performed for the logical chip module by using the data acquisition system.Experimental results showed that temporary damage could be induced on logical chip modules in spacecraft by plasma generated by hypervelocity impacts under the given experimental conditions and the sensors＇ position and azimuth.
文摘All long-duration spacecraft in low-earth-orbit are subject to high velocity impacts by meteoroids and space debris. Such impacts are expected to occur at non-normal incidence angles and can cause severe damage to the spacecraft and its external flight-critical systems and possibly lead to catastrophic failure of the spacecraft. In order to ensure crew safety and proper function of internal and external spacecraft systems, the characteristics of a debris cloud generated by such impacts must be known. An analytical model is therefore developed for the characterization of the penetration and ricochet debris clouds created by the hypervelocity impact of an aluminum spherical projectile on an aluminum plate. This model employs normal and oblique shock wave theory to characterize the penetration and ricochet processes. The prediction results of center-of-mass trajectory and leading velocity of penetration and ricochet debris clouds are obtained and compared with numerical and experimental results in figures.
