S. Chocron, James D. Walker, D. Grosch, S. Beissel, D. Durda, K. Housen
Concrete, sandstone, and, in a previous round of experiments, pumice, were tested under hypervelocity impact at SwRI. Aluminum spheres with diameters of 1 and 1.75 in were shot at a velocity of approximately 2 km/s using a 50-mm conventional powder gun. The targets were mounted on a swing so that the momentum enhancement could be measured. The size effect, i.e. comparing momentum enhancement generated by the small and large projectiles, was of particular interest in this project. The targets were also scaled, although for sandstone we were limited by the natural geometry of the rocks. The results from the experiments show a clear size effect for the concrete while sandstone did not show any size effect, possibly because of experimental artifacts. The sandstone behavior was investigated with computations using the EPIC hydrocode. The porosity and compressive strength of the sandstone used in the impact tests were measured and reported. The rock is very similar to one reported and extensively tested by Lawrence Livermore Laboratory in 1974. Two material models (Holmquist-Johnson Concrete and Johnson-Holmquist-Beissel) were fit to the data from LLL. The momentum enhancement predicted by the code is reported for different parameter studies.
{"title":"Hypervelocity Impact on Concrete and Sandstone: Momentum Enhancement from Tests and Hydrocode Simulations","authors":"S. Chocron, James D. Walker, D. Grosch, S. Beissel, D. Durda, K. Housen","doi":"10.1115/hvis2019-059","DOIUrl":"https://doi.org/10.1115/hvis2019-059","url":null,"abstract":"\u0000 Concrete, sandstone, and, in a previous round of experiments, pumice, were tested under hypervelocity impact at SwRI. Aluminum spheres with diameters of 1 and 1.75 in were shot at a velocity of approximately 2 km/s using a 50-mm conventional powder gun. The targets were mounted on a swing so that the momentum enhancement could be measured. The size effect, i.e. comparing momentum enhancement generated by the small and large projectiles, was of particular interest in this project. The targets were also scaled, although for sandstone we were limited by the natural geometry of the rocks. The results from the experiments show a clear size effect for the concrete while sandstone did not show any size effect, possibly because of experimental artifacts. The sandstone behavior was investigated with computations using the EPIC hydrocode. The porosity and compressive strength of the sandstone used in the impact tests were measured and reported. The rock is very similar to one reported and extensively tested by Lawrence Livermore Laboratory in 1974. Two material models (Holmquist-Johnson Concrete and Johnson-Holmquist-Beissel) were fit to the data from LLL. The momentum enhancement predicted by the code is reported for different parameter studies.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90253586","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}
Understanding the kinetics of phase transitions, including decomposition from reactants to products under extreme condition events is challenging. Capturing these processes require: 1) diagnostics that probe on the timescales and at energies capable of interacting with the dynamically evolving products, penetrating the opaqueness of the changing system; and 2) detectors sensitive enough to observe these events. Synchrotrons and free electron lasers provide ke-V-energy x-ray beams capable of penetrating the optical-opaqueness of the temporally evolving products. At the Dynamic Compression Sector at the Advanced Photon Source, the x-ray beam is coupled to single and two-stage gas guns capable of producing planar shocks at a range of projectile velocities while capturing in situ x-ray diffraction/scattering of the evolving material under dynamic compression. In this work, we demonstrate the utility of this approach in measuring the evolution of crystalline domains in shocked high-density polyethylene to P = 7.45 GPa, and have observed the compression and orientation of the polymer chains in real time.
{"title":"X-ray diffraction diagnostic paired with gas gun driven compression of polyethylene","authors":"R. Huber, E. Watkins, D. Dattelbaum, R. Gustavsen","doi":"10.1115/hvis2019-112","DOIUrl":"https://doi.org/10.1115/hvis2019-112","url":null,"abstract":"\u0000 Understanding the kinetics of phase transitions, including decomposition from reactants to products under extreme condition events is challenging. Capturing these processes require: 1) diagnostics that probe on the timescales and at energies capable of interacting with the dynamically evolving products, penetrating the opaqueness of the changing system; and 2) detectors sensitive enough to observe these events. Synchrotrons and free electron lasers provide ke-V-energy x-ray beams capable of penetrating the optical-opaqueness of the temporally evolving products. At the Dynamic Compression Sector at the Advanced Photon Source, the x-ray beam is coupled to single and two-stage gas guns capable of producing planar shocks at a range of projectile velocities while capturing in situ x-ray diffraction/scattering of the evolving material under dynamic compression. In this work, we demonstrate the utility of this approach in measuring the evolution of crystalline domains in shocked high-density polyethylene to P = 7.45 GPa, and have observed the compression and orientation of the polymer chains in real time.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"112 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79523701","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}
Understanding how a potentially hazardous object (PHO) responds to a kinetic impactor is of great interest to the planetary defense community. Target response depends upon the detailed material properties of the PHO, which may not be well constrained ahead of time. Hence, it is useful to explore a variety of target compositions for kinetic impact deflection. Previous validation efforts have focused primarily on understanding the behavior of common rocky materials, though PHOs are not exclusively composed of such material. Water ice is one material for which there has been only limited code validation against cratering experiments. It is known that comets consist of primarily icy material and some asteroids likely contain some amount of ice. Therefore, it is useful to understand the model sensitivities for ice in deflection simulations. Here we present Adaptive Smoothed Particle Hydrodynamics simulations of impacts into water ice by an aluminum projectile. We explore the sensitivities to the damage model within our code and find that the best-fit simulations of ice occur with a Weibull modulus of 12, though results can be obtained with values of the Weibull modulus near the published value of 9.59. This work demonstrates the efficacy of using an adaptive smoothed particle hydrodynamics code to simulate impacts into ice.
{"title":"Validating Ice Impacts Using Adaptive Smoothed Particle Hydrodynamics for Planetary Defense","authors":"D. Graninger, M. Syal, J. Owen, P. Miller","doi":"10.1115/hvis2019-102","DOIUrl":"https://doi.org/10.1115/hvis2019-102","url":null,"abstract":"\u0000 Understanding how a potentially hazardous object (PHO) responds to a kinetic impactor is of great interest to the planetary defense community. Target response depends upon the detailed material properties of the PHO, which may not be well constrained ahead of time. Hence, it is useful to explore a variety of target compositions for kinetic impact deflection. Previous validation efforts have focused primarily on understanding the behavior of common rocky materials, though PHOs are not exclusively composed of such material. Water ice is one material for which there has been only limited code validation against cratering experiments. It is known that comets consist of primarily icy material and some asteroids likely contain some amount of ice. Therefore, it is useful to understand the model sensitivities for ice in deflection simulations. Here we present Adaptive Smoothed Particle Hydrodynamics simulations of impacts into water ice by an aluminum projectile. We explore the sensitivities to the damage model within our code and find that the best-fit simulations of ice occur with a Weibull modulus of 12, though results can be obtained with values of the Weibull modulus near the published value of 9.59. This work demonstrates the efficacy of using an adaptive smoothed particle hydrodynamics code to simulate impacts into ice.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"105 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80700624","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}
H. Nahra, L. Ghosn, E. Christiansen, Joshua E. Miller, B. Davis
System level assessment of hypervelocity impacts by micrometeoroids and orbital debris (MMOD) relies on the definition of the spacecraft geometry and trajectory, the natural environment of the micrometeoroids and induced environment of the orbital space debris, ballistic limit equations and the failure criteria. The definition of the MMOD environments provides the particles flux and when is combined with the ballistic limit equations will determine the number of the critical penetrating particles that could result in the failure of the underlying component is calculated and is used to calculate the risk based on some failure criterion. Spacecraft geometry provides the shielding configuration over the spacecraft critical body which defines the selection of the ballistic limit equations to be used in the risk assessment. The definition of the failure criterion for metallic pressure systems involves the definition of the allowable depth of penetration that could result in leakage or burst of the component. This paper addresses the definition of the allowable depth of penetration of generic metallic tanks from MMOD impacts. The allowable penetration depth of metal tanks is based on a fracture mechanics approach calibrated using biaxially stressed coupons tests subjected to Hypervelocity Impacts (HVI). The planar crack-crack spacing was based on the craters spacing distribution of the HVI coupon tests. The Stress Intensity Factor (SIF) as a function of crater depths and crater spacing and applied remote stress is calculated using NASGRO®, a linear fracture mechanics software. The calculated SIF is compared with the material fracture toughness to determine if the craters result in a failure of the coupons under biaxial stress. This work resulted in a recommended allowable depth of penetration of 20% on the surfaces of metallic pressure vessels on spacecraft.
{"title":"Depth of penetration criteria on metallic surfaces for use in MMOD risk assessment","authors":"H. Nahra, L. Ghosn, E. Christiansen, Joshua E. Miller, B. Davis","doi":"10.1115/hvis2019-037","DOIUrl":"https://doi.org/10.1115/hvis2019-037","url":null,"abstract":"\u0000 System level assessment of hypervelocity impacts by micrometeoroids and orbital debris (MMOD) relies on the definition of the spacecraft geometry and trajectory, the natural environment of the micrometeoroids and induced environment of the orbital space debris, ballistic limit equations and the failure criteria. The definition of the MMOD environments provides the particles flux and when is combined with the ballistic limit equations will determine the number of the critical penetrating particles that could result in the failure of the underlying component is calculated and is used to calculate the risk based on some failure criterion. Spacecraft geometry provides the shielding configuration over the spacecraft critical body which defines the selection of the ballistic limit equations to be used in the risk assessment. The definition of the failure criterion for metallic pressure systems involves the definition of the allowable depth of penetration that could result in leakage or burst of the component. This paper addresses the definition of the allowable depth of penetration of generic metallic tanks from MMOD impacts. The allowable penetration depth of metal tanks is based on a fracture mechanics approach calibrated using biaxially stressed coupons tests subjected to Hypervelocity Impacts (HVI). The planar crack-crack spacing was based on the craters spacing distribution of the HVI coupon tests. The Stress Intensity Factor (SIF) as a function of crater depths and crater spacing and applied remote stress is calculated using NASGRO®, a linear fracture mechanics software. The calculated SIF is compared with the material fracture toughness to determine if the craters result in a failure of the coupons under biaxial stress. This work resulted in a recommended allowable depth of penetration of 20% on the surfaces of metallic pressure vessels on spacecraft.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82667158","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}
Reinforced carbon-carbon (RCC) composite is used in applications where structural stiffness and strength must be maintained at very high temperatures that may reach 2000°C or more. For example, it was used on both the Space Shuttle’s nose cone and the leading edges of its wings. As exemplified by the Space Shuttle Columbia accident, the ability of these materials to survive impacts up to hypervelocity speeds can be critical for some applications. As computational modeling becomes an increasingly important component of the design process, the ability to accurately model RCC materials under impact conditions likewise becomes more and more important. This paper describes a computational model of the thermal protection used on the Space Shuttle orbiter. The model incorporates both the RCC comprising much of the protection system and its silicon carbide coating. The model was subjected to hypervelocity impacts with both steel and aluminum projectiles, and the results were compared to test data from the literature.
{"title":"Modeling Hypervelocity Impact of Reinforced Carbon-Carbon Composite Thermal Protection System","authors":"A. Carpenter, S. Chocron, James D. Walker","doi":"10.1115/hvis2019-063","DOIUrl":"https://doi.org/10.1115/hvis2019-063","url":null,"abstract":"\u0000 Reinforced carbon-carbon (RCC) composite is used in applications where structural stiffness and strength must be maintained at very high temperatures that may reach 2000°C or more. For example, it was used on both the Space Shuttle’s nose cone and the leading edges of its wings. As exemplified by the Space Shuttle Columbia accident, the ability of these materials to survive impacts up to hypervelocity speeds can be critical for some applications. As computational modeling becomes an increasingly important component of the design process, the ability to accurately model RCC materials under impact conditions likewise becomes more and more important. This paper describes a computational model of the thermal protection used on the Space Shuttle orbiter. The model incorporates both the RCC comprising much of the protection system and its silicon carbide coating. The model was subjected to hypervelocity impacts with both steel and aluminum projectiles, and the results were compared to test data from the literature.","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":"78876505","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}
C. Cagle, K. Hill, C. Woodruff, M. Pantoya, J. Abraham, C. Meakin
Experiments were performed to study penetration through multiple aluminum plates followed by impact into an inert steel anvil using a High-velocity Impact-ignition Testing System (HITS). The projectiles are intermetallic pellets launched from a propellant driven gun into a catch chamber equipped with view ports and imaging diagnostics. Penetration, impact and reaction are monitored using high-speed cameras that provide local and macroscopic perspectives of projectile and target interaction as well as overall reactivity. Results demonstrate the range of visual data that can be captured by a non-gas generating intermetallic projectile that fragments and reacts upon penetration and impact. Results show that higher velocity projectiles (~ 1300 and 800 m/s) produce smaller fragments upon target penetration that result in flame spreading through the chamber upon impact while lower velocity projectiles (~ 500 m/s) negligibly fragment upon target penetration and produce no flames even upon anvil impact.
{"title":"High Velocity Impact Testing for Evaluation of Intermetallic Projectiles","authors":"C. Cagle, K. Hill, C. Woodruff, M. Pantoya, J. Abraham, C. Meakin","doi":"10.1115/hvis2019-104","DOIUrl":"https://doi.org/10.1115/hvis2019-104","url":null,"abstract":"\u0000 Experiments were performed to study penetration through multiple aluminum plates followed by impact into an inert steel anvil using a High-velocity Impact-ignition Testing System (HITS). The projectiles are intermetallic pellets launched from a propellant driven gun into a catch chamber equipped with view ports and imaging diagnostics. Penetration, impact and reaction are monitored using high-speed cameras that provide local and macroscopic perspectives of projectile and target interaction as well as overall reactivity. Results demonstrate the range of visual data that can be captured by a non-gas generating intermetallic projectile that fragments and reacts upon penetration and impact. Results show that higher velocity projectiles (~ 1300 and 800 m/s) produce smaller fragments upon target penetration that result in flame spreading through the chamber upon impact while lower velocity projectiles (~ 500 m/s) negligibly fragment upon target penetration and produce no flames even upon anvil impact.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79022053","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}
The DebriSat hypervelocity impact experiment, performed at the Arnold Engineering Development Center, is intended to update the catastrophic break-up models for modern satellites. To this end, the DebrisSat was built with many modern materials including structural panels of carbon-fiber, reinforced-polymer (CFRP). Subsequent to the experiment, fragments of the DebrisSat have been extracted from porous, catcher panels used to gather the debris from the impact event. Thus far, one of the key observations from the collected fragments is that CFRP represents a large fraction of the fragments and that these fragments tend to be thin, flake-like structures or long, needle-like structures; whereas, debris with nearly equal dimensions is less prevalent. As current ballistic limit models are all developed based upon spherical impacting particles, the experiment has pointed to a missing component in the current approach that must be considered. To begin to understand the implications of this observation, simulations have been performed using cylindrical structures at a representative orbital speed into an externally-insulated, double-wall shield that is representative of shielding on the current International Space Station crew transport vehicle, the Soyuz. These simulations have been performed for normal impacts to the surface with three different impact angles-of-attack to capture the effect on the shield performance. This paper documents the simulated shield and the models developed to study the effect of fragments and derives the critical characteristics of CFRP impacting particles for the selected shield. This work gives a deployable form of a critical, non-spherical projectile ballistic limit equation for evaluating non-spherical space debris for orbital debris environment modeling.
{"title":"Simulation study of non-spherical, graphite-epoxy projectiles","authors":"Joshua E. Miller","doi":"10.1115/hvis2019-044","DOIUrl":"https://doi.org/10.1115/hvis2019-044","url":null,"abstract":"\u0000 The DebriSat hypervelocity impact experiment, performed at the Arnold Engineering Development Center, is intended to update the catastrophic break-up models for modern satellites. To this end, the DebrisSat was built with many modern materials including structural panels of carbon-fiber, reinforced-polymer (CFRP). Subsequent to the experiment, fragments of the DebrisSat have been extracted from porous, catcher panels used to gather the debris from the impact event. Thus far, one of the key observations from the collected fragments is that CFRP represents a large fraction of the fragments and that these fragments tend to be thin, flake-like structures or long, needle-like structures; whereas, debris with nearly equal dimensions is less prevalent. As current ballistic limit models are all developed based upon spherical impacting particles, the experiment has pointed to a missing component in the current approach that must be considered. To begin to understand the implications of this observation, simulations have been performed using cylindrical structures at a representative orbital speed into an externally-insulated, double-wall shield that is representative of shielding on the current International Space Station crew transport vehicle, the Soyuz. These simulations have been performed for normal impacts to the surface with three different impact angles-of-attack to capture the effect on the shield performance. This paper documents the simulated shield and the models developed to study the effect of fragments and derives the critical characteristics of CFRP impacting particles for the selected shield. This work gives a deployable form of a critical, non-spherical projectile ballistic limit equation for evaluating non-spherical space debris for orbital debris environment modeling.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83219743","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}
We use PAGOSA’s FLIP+MPM capability to simulate hypervelocity impact and fragmentation from hypersonic explosions. The scenario to be simulated involves a complex chain explosion from fragmentation impact which was caused by another explosion. The simulations also use the SURF model for shock to detonation transition (SDT) and the MATCH model for mechanical ignition and deflagration of high explosives. These models in PAGOSA working together are crucial for modeling complex system for real world applications. This shows the powerful modeling and predicting capability of PAGOSA that others cannot do. Since experimental data are not available for any complex scenario like this, we did verification and validation (V&V) in each separate steps, These include the fragmentation simulated by FLIP+MPM, the Shock to Detonation Transition (SDT) modeled by SURF and mechanical ignition and deflagration modeled by MATCH. PAGOSA is a shock hydrodynamics program developed at Los Alamos National Laboratory (LANL) for the study of high-speed compressible flow and high-rate material deformation. PAGOSA is a three-dimensional Eulerian finite difference code, solving problems with a wide variety of equations of state (EOSs), material strength, and explosive modeling options. It has high efficiency for simulations running on massively parallel supercomputers. It is a multi-material code using volume of fluid (VOF) interface reconstruction and second order fully explicit time integration. Standard von Neumann artificial viscosity is used. Newly added material point method (MPM) plus Fluid-Implicit Particle (FLIP) capability can simulate high-speed metal fragmentation.
我们使用PAGOSA的FLIP+MPM功能来模拟高超音速爆炸的超高速撞击和碎片。要模拟的情景涉及由另一次爆炸引起的碎片冲击引起的复杂连锁爆炸。模拟还使用SURF模型模拟激波到爆轰过渡(SDT)， MATCH模型模拟高爆药的机械点火和爆燃。PAGOSA中的这些模型协同工作对于为现实世界的应用程序建模复杂系统至关重要。这显示了PAGOSA强大的建模和预测能力，这是其他人无法做到的。由于没有任何复杂场景的实验数据，我们在每个单独的步骤中进行了验证和验证(V&V)，其中包括FLIP+MPM模拟的破片，SURF模拟的冲击到爆轰过渡(SDT)和MATCH模拟的机械点火和爆燃。PAGOSA是美国洛斯阿拉莫斯国家实验室(Los Alamos National Laboratory, LANL)为研究高速可压缩流动和高速率材料变形而开发的激波流体动力学项目。PAGOSA是一个三维欧拉有限差分代码，可解决各种状态方程(eos)，材料强度和爆炸建模选项的问题。它在大规模并行超级计算机上具有很高的模拟效率。它是一种采用流体体积(VOF)界面重构和二阶全显式时间积分的多材料代码。采用标准冯诺依曼人工粘度。新增加的物质点法(MPM)和流体隐含粒子(FLIP)功能可以模拟高速金属破碎。
{"title":"Pagosa Simulation of Hypervelocity Impact and Fragmentation From Hypersonic Explosions","authors":"Xia Ma, D. Culp, Brandon M. Smith","doi":"10.1115/hvis2019-089","DOIUrl":"https://doi.org/10.1115/hvis2019-089","url":null,"abstract":"\u0000 We use PAGOSA’s FLIP+MPM capability to simulate hypervelocity impact and fragmentation from hypersonic explosions. The scenario to be simulated involves a complex chain explosion from fragmentation impact which was caused by another explosion. The simulations also use the SURF model for shock to detonation transition (SDT) and the MATCH model for mechanical ignition and deflagration of high explosives. These models in PAGOSA working together are crucial for modeling complex system for real world applications. This shows the powerful modeling and predicting capability of PAGOSA that others cannot do. Since experimental data are not available for any complex scenario like this, we did verification and validation (V&V) in each separate steps, These include the fragmentation simulated by FLIP+MPM, the Shock to Detonation Transition (SDT) modeled by SURF and mechanical ignition and deflagration modeled by MATCH. PAGOSA is a shock hydrodynamics program developed at Los Alamos National Laboratory (LANL) for the study of high-speed compressible flow and high-rate material deformation. PAGOSA is a three-dimensional Eulerian finite difference code, solving problems with a wide variety of equations of state (EOSs), material strength, and explosive modeling options. It has high efficiency for simulations running on massively parallel supercomputers. It is a multi-material code using volume of fluid (VOF) interface reconstruction and second order fully explicit time integration. Standard von Neumann artificial viscosity is used. Newly added material point method (MPM) plus Fluid-Implicit Particle (FLIP) capability can simulate high-speed metal fragmentation.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85967998","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}
The Debris Risk Evolution And Dispersal (DREAD) tool facilitates the 3D modeling and risk analysis of the fragmentation cloud after a collision or explosion. This tool uses the NASA Standard Breakup Model and other breakup models “under the hood” that are capable of estimating the Probability Density Function (PDF) of induced relative velocity, mass and area of fragments as a function of object size. DREAD can be further enhanced by incorporation of alternate, more detailed hypervelocity simulations that enforce conservation laws (conservation of mass, angular and linear momentum and kinetic energy). We also discuss our recent incorporation of an improved technique to normalize risk by the expansion volume occupied by debris fragments. DREAD is then used to examine the likely debris fragmentation cloud created by the Fengyun 1C (FY1C) antisatellite (ASAT) intercept test conducted by the Chinese in 2007 and the risk it subsequently posed to other spacecraft and the cloud’s evolution and dispersal.
{"title":"Debris Risk Evolution And Dispersal (DREAD) for post-fragmentation modeling","authors":"D. Oltrogge, D. Vallado","doi":"10.1115/hvis2019-054","DOIUrl":"https://doi.org/10.1115/hvis2019-054","url":null,"abstract":"\u0000 The Debris Risk Evolution And Dispersal (DREAD) tool facilitates the 3D modeling and risk analysis of the fragmentation cloud after a collision or explosion. This tool uses the NASA Standard Breakup Model and other breakup models “under the hood” that are capable of estimating the Probability Density Function (PDF) of induced relative velocity, mass and area of fragments as a function of object size. DREAD can be further enhanced by incorporation of alternate, more detailed hypervelocity simulations that enforce conservation laws (conservation of mass, angular and linear momentum and kinetic energy). We also discuss our recent incorporation of an improved technique to normalize risk by the expansion volume occupied by debris fragments. DREAD is then used to examine the likely debris fragmentation cloud created by the Fengyun 1C (FY1C) antisatellite (ASAT) intercept test conducted by the Chinese in 2007 and the risk it subsequently posed to other spacecraft and the cloud’s evolution and dispersal.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87982302","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}
Kevin Hoffman, J. Hyde, E. Christiansen, D. M. Lear
A well-known hazard associated with exposure to the space environment is the risk of vehicle failure due to an impact from a micrometeoroid and orbital debris (MMOD) particle. Among the vehicles of importance to NASA is the extravehicular mobility unit (EMU) “spacesuit” used while performing a US extravehicular activity (EVA). An EMU impact is of great concern as a large leak could prevent an astronaut from safely reaching the airlock in time resulting in a loss of life. For this reason, a risk assessment is provided to the EVA office at the Johnson Space Center (JSC) prior to certification of readiness for each US EVA. This paper will detail the methodology for an ISS EVA risk assessment. The soft goods regions (multilayer fabric over a pressurized bladder) are the highest contributors of risk for an ISS EVA. The gloves, due to reduced fabric layers to allow for improved dexterity, carry the highest risk per area. ISS EVA risk can be reduced by minimizing the exposure of the front of the suit and gloves to the orbital debris flux.
{"title":"Extravehicular Activity Micrometeoroid and Orbital Debris Risk Assessment Methodology","authors":"Kevin Hoffman, J. Hyde, E. Christiansen, D. M. Lear","doi":"10.1115/hvis2019-058","DOIUrl":"https://doi.org/10.1115/hvis2019-058","url":null,"abstract":"\u0000 A well-known hazard associated with exposure to the space environment is the risk of vehicle failure due to an impact from a micrometeoroid and orbital debris (MMOD) particle. Among the vehicles of importance to NASA is the extravehicular mobility unit (EMU) “spacesuit” used while performing a US extravehicular activity (EVA). An EMU impact is of great concern as a large leak could prevent an astronaut from safely reaching the airlock in time resulting in a loss of life. For this reason, a risk assessment is provided to the EVA office at the Johnson Space Center (JSC) prior to certification of readiness for each US EVA. This paper will detail the methodology for an ISS EVA risk assessment. The soft goods regions (multilayer fabric over a pressurized bladder) are the highest contributors of risk for an ISS EVA. The gloves, due to reduced fabric layers to allow for improved dexterity, carry the highest risk per area. ISS EVA risk can be reduced by minimizing the exposure of the front of the suit and gloves to the orbital debris flux.","PeriodicalId":6596,"journal":{"name":"2019 15th Hypervelocity Impact Symposium","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74977095","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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