In this paper, with different cone angles of the liner, the effects of the additional body’s material, thickness, and diameter on the velocity are studied by AUTODYN-2D. The results show as follows: 1. The additional body can increase the top velocity of the jet but has little effect on the tail velocity. 2. When the cone angle is larger, the velocity increases more, about 36%, and the velocity gradient is greater at the head of the jet. 3. There is little influence of material yield strength, but there is a large correlation with density. With the increase of material density, the velocity and velocity gradient increase. 4. The larger the density of the additional body, the smaller the optimum thickness. When the thickness is not less than the optimum thickness, an increase in the diameter of the additional body can improve the velocity and stability of the jet. Consequently, this kind of hyper-cumulation structure with a flat plate additional body is more suitable to improve the classical liner with a large cone angle. By modifying the design of the shaped charge in this way, the velocity of the jet can be improved effectively, enhancing the penetration power compared with the classical one.
{"title":"Effects of Additional Body on Jet Velocity of Hyper-cumulation","authors":"Xu Mengwen, Jia Xin, Huang Zhengxiang","doi":"10.1115/hvis2019-094","DOIUrl":"https://doi.org/10.1115/hvis2019-094","url":null,"abstract":"\u0000 In this paper, with different cone angles of the liner, the effects of the additional body’s material, thickness, and diameter on the velocity are studied by AUTODYN-2D. The results show as follows: 1. The additional body can increase the top velocity of the jet but has little effect on the tail velocity. 2. When the cone angle is larger, the velocity increases more, about 36%, and the velocity gradient is greater at the head of the jet. 3. There is little influence of material yield strength, but there is a large correlation with density. With the increase of material density, the velocity and velocity gradient increase. 4. The larger the density of the additional body, the smaller the optimum thickness. When the thickness is not less than the optimum thickness, an increase in the diameter of the additional body can improve the velocity and stability of the jet. Consequently, this kind of hyper-cumulation structure with a flat plate additional body is more suitable to improve the classical liner with a large cone angle. By modifying the design of the shaped charge in this way, the velocity of the jet can be improved effectively, enhancing the penetration power compared with the classical one.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73344283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuki Mando, Koji Tanaka, T. Hirai, S. Kawakita, M. Higashide, H. Kurosaki, S. Hasegawa, K. Nitta
Space debris travels at a velocity of 7-8 km/s in low Earth orbit (LEO) and at 3 km/s in geostationary Earth orbit (GEO). An impact between space debris and spacecraft will result in tremendous damage. In particular, particles less than 1mm in diameter pose a risk of causing permanent sustained discharge (PSD). PSD may affect a satellite’s power system. The effect on solar arrays has been well-studied given their large area, but the effect on the bundle of a satellite’s wire harness (called the power harness) has yet to be clarified, even though the power harness is usually exposed to the space environment without protection. We conducted hypervelocity impact experiments using a two-stage light gas gun, and investigated the risk resulting in PSD from hypervelocity impacts of particles less than 1mm in size. In addition, we compared two kinds of circuit configurations: a more realistic circuit configuration with internal resistance and a circuit configuration without it, so as to investigate whether internal resistance affects the occurrence of PSD. Stainless steel and aluminum oxide projectiles measuring from 0.3 to 1 mm in diameter were gun-accelerated up to 7.16 km/s. Targets entailed a three-layered power harness under a simulated power condition of typical satellites operating in LEO or GEO. As a result, 11 of 28 shots resulted in PSD. With the more realistic circuit configuration we could not confirm any results regarding PSD. We thus found that PSD is less likely to occur in a more realistic circuit configuration.
{"title":"Investigation on Sustained Discharge of Satellite’s Power Harness Due to Plasma from Space Debris Impact","authors":"Yuki Mando, Koji Tanaka, T. Hirai, S. Kawakita, M. Higashide, H. Kurosaki, S. Hasegawa, K. Nitta","doi":"10.1115/HVIS2019-019","DOIUrl":"https://doi.org/10.1115/HVIS2019-019","url":null,"abstract":"\u0000 Space debris travels at a velocity of 7-8 km/s in low Earth orbit (LEO) and at 3 km/s in geostationary Earth orbit (GEO). An impact between space debris and spacecraft will result in tremendous damage. In particular, particles less than 1mm in diameter pose a risk of causing permanent sustained discharge (PSD). PSD may affect a satellite’s power system. The effect on solar arrays has been well-studied given their large area, but the effect on the bundle of a satellite’s wire harness (called the power harness) has yet to be clarified, even though the power harness is usually exposed to the space environment without protection. We conducted hypervelocity impact experiments using a two-stage light gas gun, and investigated the risk resulting in PSD from hypervelocity impacts of particles less than 1mm in size. In addition, we compared two kinds of circuit configurations: a more realistic circuit configuration with internal resistance and a circuit configuration without it, so as to investigate whether internal resistance affects the occurrence of PSD. Stainless steel and aluminum oxide projectiles measuring from 0.3 to 1 mm in diameter were gun-accelerated up to 7.16 km/s. Targets entailed a three-layered power harness under a simulated power condition of typical satellites operating in LEO or GEO. As a result, 11 of 28 shots resulted in PSD. With the more realistic circuit configuration we could not confirm any results regarding PSD. We thus found that PSD is less likely to occur in a more realistic circuit configuration.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74778546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Equation of state properties were studied for the high-lead glass Corning 0120, which is a potash-soda-lead glass also referred to as G12. This glass, which contains approximately 30% PbO by weight and has a density, ρo, of 3.034 g/cm3 possesses properties suitable for many applications in industry such as optical components for space exploration instrumentation. Further understanding of its mechanical properties is desired for more complex applications in various fields, including applications where the glass may experience high-pressure shock loading. In this work plate impact experiments were conducted to determine the dynamic response of Corning 0120 at high stress levels. Tests were conducted over the pressure range from approximately 5 to 24 GPa utilizing the 90 mm bore single-stage powder driven gas gun at the Sandia National Laboratories STAR Facility. For this study, we used one-inch diameter Corning 0120 glass samples of two different thicknesses (3 mm and 7 mm) to use the evolution of the shock wave propagation through the material for analysis. The time-resolved material response was measured by means of a Velocity Interferometer System for Any Reflector system (VISAR). Results will be presented detailing the high-pressure shock loading response characteristics of the high-lead glass Corning 0120. Comparisons are made with similar results for lead free glass to assess the most prominent changes compared to lower density glasses and other lead filled glasses.
{"title":"Corning0120 High-Lead Glass Subject to Shock Loading","authors":"B. Farfan, W. Reinhart, S. Alexander","doi":"10.1115/hvis2019-031","DOIUrl":"https://doi.org/10.1115/hvis2019-031","url":null,"abstract":"\u0000 Equation of state properties were studied for the high-lead glass Corning 0120, which is a potash-soda-lead glass also referred to as G12. This glass, which contains approximately 30% PbO by weight and has a density, ρo, of 3.034 g/cm3 possesses properties suitable for many applications in industry such as optical components for space exploration instrumentation. Further understanding of its mechanical properties is desired for more complex applications in various fields, including applications where the glass may experience high-pressure shock loading. In this work plate impact experiments were conducted to determine the dynamic response of Corning 0120 at high stress levels. Tests were conducted over the pressure range from approximately 5 to 24 GPa utilizing the 90 mm bore single-stage powder driven gas gun at the Sandia National Laboratories STAR Facility. For this study, we used one-inch diameter Corning 0120 glass samples of two different thicknesses (3 mm and 7 mm) to use the evolution of the shock wave propagation through the material for analysis. The time-resolved material response was measured by means of a Velocity Interferometer System for Any Reflector system (VISAR). Results will be presented detailing the high-pressure shock loading response characteristics of the high-lead glass Corning 0120. Comparisons are made with similar results for lead free glass to assess the most prominent changes compared to lower density glasses and other lead filled glasses.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"68 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80270289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Tasker, Y. Bae, Carl Johnson, K. Rainey, C. Campbell, D. Oschwald, C. Reed
Using a Voitenko accelerator [1-3], a series of experiments were performed with the goal of attaining shock velocities in gases approaching 90 km/s. Typically, the basic apparatus comprises a hemispherical bowl filled with a gas at atmospheric pressure; a metal piston across its diameter; and a small bore evacuated shock tube at its apex, Fig. 1. The evacuated shock tube is separated from the gas bowl by a thin diaphragm. A combination of a plane wave explosive lens and a high explosive pad accelerates the piston to a velocity of the order of 4 km/s and subsequently compresses the gas in the bowl. The thin diaphragm at the other end of the bowl then ruptures and the high pressure (shock compressed) gas escapes into the shock tube.
{"title":"Voitenko experiments with novel diagnostics detect velocities of 89 km/s","authors":"D. Tasker, Y. Bae, Carl Johnson, K. Rainey, C. Campbell, D. Oschwald, C. Reed","doi":"10.1115/hvis2019-081","DOIUrl":"https://doi.org/10.1115/hvis2019-081","url":null,"abstract":"\u0000 Using a Voitenko accelerator [1-3], a series of experiments were performed with the goal of attaining shock velocities in gases approaching 90 km/s. Typically, the basic apparatus comprises a hemispherical bowl filled with a gas at atmospheric pressure; a metal piston across its diameter; and a small bore evacuated shock tube at its apex, Fig. 1. The evacuated shock tube is separated from the gas bowl by a thin diaphragm. A combination of a plane wave explosive lens and a high explosive pad accelerates the piston to a velocity of the order of 4 km/s and subsequently compresses the gas in the bowl. The thin diaphragm at the other end of the bowl then ruptures and the high pressure (shock compressed) gas escapes into the shock tube.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85840176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Banton, T. Piehler, N. Zander, R. Benjamin, J. Duckworth, O. Petel
There is an urgent need to understand the mechanism leading to mild traumatic brain injury (mTBI) resulting from blast wave impact to the head. The recent conflicts in Iraq and Afghanistan have heightened the awareness of head impact injuries to military personnel resulting from exposure to blast waves [1, 2]. A blast wave generated in air is a by-product of the detonation of an explosive [3]. To date the mechanism resulting in mTBI from primary blast insult is still unclear.
{"title":"Investigating Pressure Wave Impact on a Surrogate Head Model Using Numerical Simulation Techniques","authors":"R. Banton, T. Piehler, N. Zander, R. Benjamin, J. Duckworth, O. Petel","doi":"10.1115/hvis2019-113","DOIUrl":"https://doi.org/10.1115/hvis2019-113","url":null,"abstract":"\u0000 There is an urgent need to understand the mechanism leading to mild traumatic brain injury (mTBI) resulting from blast wave impact to the head. The recent conflicts in Iraq and Afghanistan have heightened the awareness of head impact injuries to military personnel resulting from exposure to blast waves [1, 2]. A blast wave generated in air is a by-product of the detonation of an explosive [3]. To date the mechanism resulting in mTBI from primary blast insult is still unclear.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90571956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
JeMMA, a set of relatively simple shaped-charge devices, has been designed in order to generate suitable data on jet formation, break-up and penetration for code validation purposes. The JeMMA Phase 1 device incorporated a copper liner and six of these shaped charges were manufactured as a technology demonstrator and fired in a special shaped charge facility in December 2016. The radiographic results obtained from the JeMMA Phase 1 and 2 devices, along with data reproducibility between trials, was excellent. This report gives an overview of the Phase 1 and 2 trials, including device design, the results of the firings conducted in Switzerland and details of the subsequent 2D and 3D hydrocode modelling carried out at AWE. The agreement between the data and both 2D and 3D modelling of the experiments is very pleasing, but highlights where further work is required. These JeMMA experiments will enhance the body of relevant data required to provide the validation of the hydrocode materials and modelling methodologies and enable us to better model the jetting threats of our experiments and have higher confidence in the results of the modelling.
{"title":"Towards a Better Understanding of Shaped Charge Jet Formation and Penetration","authors":"D. Price, E. Harris, Frances G. Daykin","doi":"10.1115/hvis2019-014","DOIUrl":"https://doi.org/10.1115/hvis2019-014","url":null,"abstract":"\u0000 JeMMA, a set of relatively simple shaped-charge devices, has been designed in order to generate suitable data on jet formation, break-up and penetration for code validation purposes. The JeMMA Phase 1 device incorporated a copper liner and six of these shaped charges were manufactured as a technology demonstrator and fired in a special shaped charge facility in December 2016. The radiographic results obtained from the JeMMA Phase 1 and 2 devices, along with data reproducibility between trials, was excellent. This report gives an overview of the Phase 1 and 2 trials, including device design, the results of the firings conducted in Switzerland and details of the subsequent 2D and 3D hydrocode modelling carried out at AWE. The agreement between the data and both 2D and 3D modelling of the experiments is very pleasing, but highlights where further work is required. These JeMMA experiments will enhance the body of relevant data required to provide the validation of the hydrocode materials and modelling methodologies and enable us to better model the jetting threats of our experiments and have higher confidence in the results of the modelling.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75790322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerical modeling has been conducted with the commercial code AUTODYN 2D, using the Lagrange and Smooth Particle Hydrodynamics (SPH) processors. The numerical results are compared and discussed with the corresponding experimental results from the standpoint of assessing the protection of satellites against M/OD hypervelocity impacts. The material models used in the numerical simulation are also discussed, as well as a wide range of impact velocities, including shock-induced vaporization. The projectiles used to simulate M/OD consist of 100 μm to 1 mm diameter alumina with impact velocities of 2–15 km/s. In order to assess the structural integrity of unmanned spacecraft subjected to the threat of hypervelocity impact by space debris, the numerical method was proposed mainly from the standpoint of material modeling suitable for extremely severe physical conditions such as high pressure, high temperature, high strain, and high strain rate, sometimes accompanied by shock-induced vaporization. The numerical results adopting these material models were compared with the corresponding hypervelocity impact tests by using the two-stage light-gas gun at ISAS/JAXA. Although examples of the impacts on the aluminum honeycomb can be shown, it has been demonstrated that the numerical analysis can effectively simulate the overall corresponding experimental results. We show the response of an aluminum honeycomb as derived from analysis of hypervelocity impact at 2 km/s to 15 km/s using the Lagrange and SPH processors. We also verified that the ballistic limit curve of an aluminum honeycomb panel is shown as a downward line using both processors, which is unlike the up and down ballistic limit curve of a Whipple shield.
{"title":"Investigation on Response of an Aluminum Honeycomb Subjected to Hypervelocity Impacts using Lagrange and SPH for Numerical Modeling","authors":"K. Nitta, M. Higashide, M. Sueki, A. Takeba","doi":"10.1115/hvis2019-048","DOIUrl":"https://doi.org/10.1115/hvis2019-048","url":null,"abstract":"\u0000 Numerical modeling has been conducted with the commercial code AUTODYN 2D, using the Lagrange and Smooth Particle Hydrodynamics (SPH) processors. The numerical results are compared and discussed with the corresponding experimental results from the standpoint of assessing the protection of satellites against M/OD hypervelocity impacts. The material models used in the numerical simulation are also discussed, as well as a wide range of impact velocities, including shock-induced vaporization. The projectiles used to simulate M/OD consist of 100 μm to 1 mm diameter alumina with impact velocities of 2–15 km/s.\u0000 In order to assess the structural integrity of unmanned spacecraft subjected to the threat of hypervelocity impact by space debris, the numerical method was proposed mainly from the standpoint of material modeling suitable for extremely severe physical conditions such as high pressure, high temperature, high strain, and high strain rate, sometimes accompanied by shock-induced vaporization.\u0000 The numerical results adopting these material models were compared with the corresponding hypervelocity impact tests by using the two-stage light-gas gun at ISAS/JAXA. Although examples of the impacts on the aluminum honeycomb can be shown, it has been demonstrated that the numerical analysis can effectively simulate the overall corresponding experimental results.\u0000 We show the response of an aluminum honeycomb as derived from analysis of hypervelocity impact at 2 km/s to 15 km/s using the Lagrange and SPH processors. We also verified that the ballistic limit curve of an aluminum honeycomb panel is shown as a downward line using both processors, which is unlike the up and down ballistic limit curve of a Whipple shield.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80064367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tan Ya-ping, Jia Xin, Huang Zhengxiang, Cai Youer, Zu Xudong
In order to study the influence of liquid parameters on the protective performance of liquid composite targets (LCT), based on the theory of interaction between the jet and the LCT, three dimensionless numbers - C, G, and V - are obtained by dimensional analysis in this paper. These 3 dimensionless parameters represent the compressibility, inertia, and viscosity of the liquid, respectively. The empirical formula, P/H = 0.346C1.251G−0.7120V0.036, was obtained by fitting experimental data of the static depth of penetration (DOP) experiment which can predict the residual depth of penetration (RDOP) of the jet penetrating the LCT. It turns out that the 2 dimensionless parameters - C and G - which characterize the compressibility and inertia of the liquid, plays a decisive role in the protection performance of the LCT, while the influence of liquid viscosity is small. In addition, according to the research results of this paper, the protective performance of the LCT can be improved by selecting a liquid with high sound velocity, high viscosity, and low density.
{"title":"Effect of Liquid Parameters on Protective Performance of a Liquid Composite Target Subjected to Jet Impact","authors":"Tan Ya-ping, Jia Xin, Huang Zhengxiang, Cai Youer, Zu Xudong","doi":"10.1115/hvis2019-093","DOIUrl":"https://doi.org/10.1115/hvis2019-093","url":null,"abstract":"\u0000 In order to study the influence of liquid parameters on the protective performance of liquid composite targets (LCT), based on the theory of interaction between the jet and the LCT, three dimensionless numbers - C, G, and V - are obtained by dimensional analysis in this paper. These 3 dimensionless parameters represent the compressibility, inertia, and viscosity of the liquid, respectively. The empirical formula, P/H = 0.346C1.251G−0.7120V0.036, was obtained by fitting experimental data of the static depth of penetration (DOP) experiment which can predict the residual depth of penetration (RDOP) of the jet penetrating the LCT. It turns out that the 2 dimensionless parameters - C and G - which characterize the compressibility and inertia of the liquid, plays a decisive role in the protection performance of the LCT, while the influence of liquid viscosity is small. In addition, according to the research results of this paper, the protective performance of the LCT can be improved by selecting a liquid with high sound velocity, high viscosity, and low density.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"118 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77421179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Daly, O. Barnouin, A. Lennon, A. Stickle, E. Rainey, C. Ernst, A. Knuth
The Planetary Impact Lab (PIL) at the Johns Hopkins University Applied Physics Laboratory (JHUAPL) includes a single-stage, compressed inert gas gun that can be used for impact experiments. The impact angle can be varied from 15° to 90° with respect to horizontal, a capability which enables oblique impacts into unconsolidated or granular materials (e.g., regolith analogs). The gun currently achieves impact velocities up to 400 m/s, although future enhancements could increase the maximum projectile velocity. Experiments can be done with atmospheric pressures ranging from ambient pressure down to ~75 Pa. The gun uses sabots produced with state-of-the-art additive manufacturing techniques (AM). Several engineering challenges had to be overcome to create a reliable AM sabot; however, AM sabots are ~45% lighter than and provide substantial cost savings over machined sabots. The PIL gun is currently being used to investigate impact processes on sloped coarse-grained surfaces, with application to planetary science and, specifically, rubble-pile asteroids. In contrast to previous studies of impacts onto slopes, we kept the projectile trajectory perpendicular to the target surface, thereby disentangling the effects of oblique impacts from the effects caused by a sloped surface. Initial results show enhanced crater collapse in the sloped target, with most of the collapse occurring in the direction parallel to the surface gradient. Consequently, final craters on sloped targets have smaller volumes and reduced depth-to-diameter ratios.
{"title":"The JHUAPL Planetary Impact Lab (PIL): Capabilities and initial results","authors":"R. Daly, O. Barnouin, A. Lennon, A. Stickle, E. Rainey, C. Ernst, A. Knuth","doi":"10.1115/hvis2019-084","DOIUrl":"https://doi.org/10.1115/hvis2019-084","url":null,"abstract":"\u0000 The Planetary Impact Lab (PIL) at the Johns Hopkins University Applied Physics Laboratory (JHUAPL) includes a single-stage, compressed inert gas gun that can be used for impact experiments. The impact angle can be varied from 15° to 90° with respect to horizontal, a capability which enables oblique impacts into unconsolidated or granular materials (e.g., regolith analogs). The gun currently achieves impact velocities up to 400 m/s, although future enhancements could increase the maximum projectile velocity. Experiments can be done with atmospheric pressures ranging from ambient pressure down to ~75 Pa. The gun uses sabots produced with state-of-the-art additive manufacturing techniques (AM). Several engineering challenges had to be overcome to create a reliable AM sabot; however, AM sabots are ~45% lighter than and provide substantial cost savings over machined sabots. The PIL gun is currently being used to investigate impact processes on sloped coarse-grained surfaces, with application to planetary science and, specifically, rubble-pile asteroids. In contrast to previous studies of impacts onto slopes, we kept the projectile trajectory perpendicular to the target surface, thereby disentangling the effects of oblique impacts from the effects caused by a sloped surface. Initial results show enhanced crater collapse in the sloped target, with most of the collapse occurring in the direction parallel to the surface gradient. Consequently, final craters on sloped targets have smaller volumes and reduced depth-to-diameter ratios.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85069926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Poole, M. Gonzales, M. R. French, W. Yarberry, Abdel R. Moustafa, Z. Cordero
Shielding elements used to protect against micrometeoroids and orbital debris (MMOD) (e.g., Whipple shields, multi-shock shields, stuffed Whipple shields) typically incorporate thin bumper sheets that intercept and vaporize incident MMOD traveling at speeds in excess of several km/s. In some applications, however, space limitations prevent the use of large stand-offs, and components must instead be protected by a single monolithic shielding element. Electronics, for example, are often only protected by their housing. With such applications in mind, we describe a class of spatially efficient composite shielding elements fabricated using a hybrid additive manufacturing approach termed PrintCasting. The PrintCast process consists of two steps: First selective laser melting is used to fabricate a lattice preform in the shape of the final component. Next this preform is infiltrated with a liquid metal that has a melting point lower than that of the lattice. The resulting solidified part is a periodic interpenetrating composite in which each constituent forms a continuous network. Using a combination of hypervelocity impact experiments and shock transmission calculations, we demonstrate that these interpenetrating composite shielding elements mitigate spallation and other failure modes through multiple internal shock reflections at the buried heterophase interfaces.
{"title":"Hypervelocity impact of PrintCast A356/316L composites","authors":"L. Poole, M. Gonzales, M. R. French, W. Yarberry, Abdel R. Moustafa, Z. Cordero","doi":"10.1115/hvis2019-118","DOIUrl":"https://doi.org/10.1115/hvis2019-118","url":null,"abstract":"\u0000 Shielding elements used to protect against micrometeoroids and orbital debris (MMOD) (e.g., Whipple shields, multi-shock shields, stuffed Whipple shields) typically incorporate thin bumper sheets that intercept and vaporize incident MMOD traveling at speeds in excess of several km/s. In some applications, however, space limitations prevent the use of large stand-offs, and components must instead be protected by a single monolithic shielding element. Electronics, for example, are often only protected by their housing. With such applications in mind, we describe a class of spatially efficient composite shielding elements fabricated using a hybrid additive manufacturing approach termed PrintCasting. The PrintCast process consists of two steps: First selective laser melting is used to fabricate a lattice preform in the shape of the final component. Next this preform is infiltrated with a liquid metal that has a melting point lower than that of the lattice. The resulting solidified part is a periodic interpenetrating composite in which each constituent forms a continuous network. Using a combination of hypervelocity impact experiments and shock transmission calculations, we demonstrate that these interpenetrating composite shielding elements mitigate spallation and other failure modes through multiple internal shock reflections at the buried heterophase interfaces.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91313864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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