Aluminum Shield Under Hypervelocity Impact of Mylar Flyer

2008 ◽  
Author(s):  
J. Zhao ◽  
F. Tan ◽  
C. Liu ◽  
C. Sun
Keyword(s):  
High Speed ◽  
Hypervelocity Impact ◽  
Space Environment ◽  
Lateral Expansion ◽  
Near Earth Space ◽  
The Third ◽  
Naturally Occurring ◽  
Debris Cloud ◽  
The Impact ◽  
Different Thickness

The near-earth space environment is cluttered with man-made debris and naturally occurring meteoroids, which is a big menace to the safety of satellites and spacecrafts. This paper is addressed on the failure response of aluminum shields under hypervelocity impact of milligrame level flyer. A compacted electric gun is employed to accelerate a mylar flyer up to 10 km/s. Failure response of Ly12 aluminum shields with different thickness and layers impacted by mylar flyer with different velocities is under investigation. The spallation is observed in the rear free surface of 4 mm thick monolithic aluminum shield, and its fracture mechanism changes from plastic to brittle when loading pressure is above 13 GPa. A perforation with a diameter 8 mm in the impacted area of the 4mm thick Ly12 shield is observed after which is impacted by 0.1 mm thick mylar flyer 8mm in diameter with velocity 8.2 km/s. When three layers of shields are impacted, the debris clouds (DC) are observed in the first and the second spaces respectively during the impact process by high speed camera, and its leftover can be observed on the surface of the third plate. The shape of the first debris cloud head is a little flat, and its speed of lateral expansion is very slow, which is different from those impacted by spherical projectile, and its formation mechanics mainly attributes to multi-spallations based on the analysis of simulation.

Debris/Micrometeoroid Impacts and Synergistic Effects on Spacecraft Materials

MRS Bulletin ◽  
2010 ◽  
Vol 35 (1) ◽  
pp. 41-47 ◽  
Author(s):  
E. Grossman ◽  
I. Gouzman ◽  
R. Verker
Keyword(s):  
Space Debris ◽  
Synergistic Effects ◽  
Degradation Mechanism ◽  
Space Environment ◽  
Materials Properties ◽  
Gas Gun ◽  
Naturally Occurring ◽  
Space Activity ◽  
The Impact ◽  
Debris Impact

AbstractIn the last 40 years, the increased space activity created a new form of space environment of hypervelocity objects—space debris—that have no functional use. The space debris, together with naturally occurring ultrahigh velocity meteoroids, presents a significant hazard to spacecraft. Collision with space debris or meteoroids might result in disfunction of external units such as solar cells, affecting materials properties, contaminating optical devices, or destroying satellites. The collision normally results in the formation of additional debris, increasing the hazard for future missions. The hypervelocity debris effect is studied by retrieving materials from space or by using ground simulation facilities. Simulation facilities, which include the light gas gun and Laser Driven Flyer methods, are used for studying the materials degradation due to debris impact. The impact effect could be accelerated when occurring simultaneously with other space environment components, such as atomic oxygen, ultraviolet, or x-ray radiation. Understanding the degradation mechanism might help in developing materials that will withstand the increasing hazard from the space debris, allowing for longer space missions. The large increase in space debris population and the associated risk to space activity requires significant measures to mitigate this hazard. Most current efforts are being devoted to prevention of collisions by keeping track of the larger debris and avoiding formation of new debris.

Interplay of bubble injections in the plasma sheet dynamics as inferred from RCM-I simulations

2020 ◽  
Author(s):  
Sina Sadeghzadeh ◽  
Jian Yang
Keyword(s):  
Plasma Sheet ◽  
High Speed ◽  
Space Environment ◽  
Inner Magnetosphere ◽  
Near Earth Space ◽  
Hot Plasma ◽  
Plasma Distribution ◽  
Rice Convection Model ◽  
Convection Model ◽  
Interchange Instability

<p><span>Understanding the transport of hot plasma from tail towards the inner magnetosphere is of great importance to improve our perception of the near-Earth space environment. In accordance with the recent observations, the contribution of bursty bulk flows (BBFs)/bubbles in the inner plasma sheet especially in the storm-time ring current formation is nonnegligible. These high-speed plasma flows with depleted flux tube/entropy are likely formed in the mid tail due to magnetic reconnection and injected earthward as a result of interchange instability. In this presentation, we investigate the interplay of these meso-scale structures on the average magnetic field and plasma distribution in various regions of the plasma sheet, using the Inertialized Rice Convection Model (RCM-I). We will discuss the comparison of our simulation results with the observational statistics and data-based empirical models.</span></p>

scholarly journals Common lesions of the distal end of the third metacarpal/metatarsal bone in racehorse catastrophic breakdown injuries

2017 ◽  
Vol 29 (4) ◽  
pp. 431-436 ◽  
Author(s):  
Jennifer G. Janes ◽  
Laura A. Kennedy ◽  
Katherine S. Garrett ◽  
Julie B. Engiles
Keyword(s):  
Articular Cartilage ◽  
High Speed ◽  
Postmortem Examination ◽  
Metatarsal Bone ◽  
Osteochondral Lesions ◽  
Contralateral Limb ◽  
The Third ◽  
Catastrophic Injury ◽  
Training History ◽  
The Impact

Equine catastrophic skeletal breakdown injury is a serious issue within the racing industry, given the impact on equine and human health. The metacarpo- and metatarso-phalangeal (fetlock) joints are common sites of catastrophic injury. However, lesions involving articular cartilage, subchondral bone, and synovium are commonly identified within the fetlock of the contralateral limb; hence, it is imperative that lesions in both limbs are evaluated and characterized during postmortem examination. Bone and articular cartilage changes typically occur in specific locations, related to cyclic fetlock load and overextension during high-speed exercise. Associations between preexisting degenerative fetlock lesions and catastrophic injury are a focus of continued research. These lesions often occur because of adaptive failure related to cumulative damage. Further investigation of these lesions is imperative to determine their impact on equine performance or injury. Ultimately, consistent documentation of catastrophic versus non-catastrophic osteochondral lesions provided by pathologists, in the context of training history, diagnostic imaging, and the presence or absence of catastrophic injury, will contribute to further understanding of skeletal responses associated with catastrophic failure.

scholarly journals Atomistic Simulations on Metal Rod Penetrating Thin Target at Nanoscale Caused by High-Speed Collision

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3160
Author(s):  
Yong-Chao Wu ◽  
Jin-Ming Liu ◽  
Wei Xie ◽  
Qing Yin ◽  
Jian-Li Shao
Keyword(s):  
High Speed ◽  
Damage Mechanism ◽  
Linear Increase ◽  
Hypervelocity Impact ◽  
Atomistic Simulations ◽  
Micro Deformation ◽  
Localized Plastic Deformation ◽  
Scientific Value ◽  
Solid Liquid ◽  
The Impact

The penetration process has attracted increasing attention due to its engineering and scientific value. In this work, we investigate the deformation and damage mechanism about the nanoscale penetration of single-crystal aluminum nanorod with atomistic simulations, where distinct draw ratio (∅) and different incident velocities (up) are considered. The micro deformation processes of no penetration state (within 2 km/s) and complete penetration (above 3 km/s) are both revealed. The high-speed bullet can cause high pressure and temperature at the impacted region, promoting the localized plastic deformation and even solid-liquid phase transformation. It is found that the normalized velocity of nanorod reduces approximately exponentially during penetration (up < 3 km/s), but its residual velocity linearly increased with initial incident velocity. Moreover, the impact crater is also calculated and the corresponding radius is manifested in the linear increase trend with up while inversely proportional to the ∅. Interestingly, the uniform fragmentation is observed instead of the intact spallation, attributed to the relatively thin thickness of the target. It is additionally demonstrated that the number of fragments increases with increasing up and its size distribution shows power law damping nearly. Our findings are expected to provide the atomic insight into the micro penetration phenomena and be helpful to further understand hypervelocity impact related domains.

Protection properties of stuffed corrugated sandwich structures under hypervelocity impact: Numerical simulation

2017 ◽  
Vol 21 (2) ◽  
pp. 532-551 ◽  
Author(s):  
Hao Zhou ◽  
Rui Guo ◽  
Rongzhong Liu
Keyword(s):  
Numerical Simulation ◽  
Sandwich Structure ◽  
Hypervelocity Impact ◽  
Orbital Debris ◽  
Protection Mechanism ◽  
Broad Application ◽  
Waves Propagation ◽  
Debris Cloud ◽  
Impact Characteristics ◽  
The Impact

The stuffed corrugated sandwich structure was proposed for the application in the protection of the spacecraft against orbital debris. In order to investigate the protection properties of the stuffed corrugated sandwich structure under hypervelocity impact, numerical simulations were carried out to analyze the impact characteristics. The hypervelocity impact process was presented and the properties such as shock waves propagation, energy absorption, and expansion of the debris cloud were discussed; corresponding properties of mass equal Whipple structure under impact were analyzed for comparison. The results illustrate the protection mechanism of the stuffed corrugated sandwich subject to hypervelocity impact and show that it has superior protection performance to monolithic plate, which prove that the stuffed corrugated sandwich structure has potentially broad application prospect in the field of spacecraft protection against the orbital debris. The research can provide reference for the design of protection shield of the spacecraft.

scholarly journals Debris Cloud Material Characterization for Hypervelocity Impacts of Single- and Multimaterial Projectiles on Thin Target Plates

1995 ◽  
Vol 2 (4) ◽  
pp. 273-287 ◽  
Author(s):  
William P. Schonberg
Keyword(s):  
Damage Assessment ◽  
High Speed ◽  
Center Of Mass ◽  
Leading Edge ◽  
Hypervelocity Impact ◽  
Cloud Formation ◽  
Assessment Methodology ◽  
High Speed Impact ◽  
Debris Cloud ◽  
Cloud Material

The key to conducting an accurate damage assessment of a target impacted by a high speed projectile is the use of a robust assessment methodology. To accurately determine total target damage, a damage assessment methodology must include the effects of discrete impacts by solid debris cloud fragments as well as impulsive loadings due to molten and vaporous debris cloud material. As a result, the amount of debris cloud material in each of the three states of matter must be known to accurately assess total target damage and break-up due to a high speed impact. This article presents a first-principles based method to calculate: the amount of material in a debris cloud created by a perforating hypervelocity impact that is solid, molten, and vaporous; the debris cloud leading edge, trailing edge, center-of-mass, and expansion velocities; and the angular spread of the debris cloud material. The predictions of this methodology are compared against those of empirically based lethality assessment schemes as well as numerical and empirical results obtained in previous studies of debris cloud formation.

Long-term effects of an insecticide on a stored-wheat ecosystem

1986 ◽  
Vol 64 (11) ◽  
pp. 2558-2569 ◽  
Author(s):  
N. D. G. White ◽  
R. N. Sinha ◽  
J. T. Mills
Keyword(s):  
Principal Component ◽  
Seed Infection ◽  
Long Term Effects ◽  
Stored Wheat ◽  
The Third ◽  
Naturally Occurring ◽  
Residue Levels ◽  
Grain Bulk ◽  
The Impact

Two granaries near Winnipeg, each containing 141 of dry wheat, were filled in September 1982 and the impact of a contact insecticide on the ecosystem was determined monthly for 27 months. The wheat in one granary was treated with malathion prior to storage and the wheat in the other was left untreated. Variables monitored throughout each bulk included: introduced insect and naturally occurring mite numbers, seed germination, seed-borne mycoflora, insecticide residue levels, and seed temperature and moisture. There were significant differences (P < 0.01) in most variables within granaries between samples from the top of the grain bulk and 1-m depth. Multivariate analysis of variance indicated significantly more (P < 0.01) arthropods and more seed infection by the fungus Penicillium in the control granary. Principal component analysis of data from each granary on each sampling date indicated the first components, which accounted for most of the variation in the systems, mainly involved temperature, moisture, fungi, and insecticide (when present); the second components involved fungi; and the third components involved fungi and arthropods, even in the treated ecosystem. The presence of a contact insecticide in a stored-wheat ecosystem had significant effects on the faunal community and definite but less conspicuous effects on the mycofloral community.

Numerical Simulation of Hypervelocity Impact on Mesh Bumper Causing Fragmentation and Ejection

2012 ◽  
Vol 525-526 ◽  
pp. 401-404
Author(s):  
Gong Shun Guan ◽  
Rui Tao Niu
Keyword(s):  
Numerical Simulation ◽  
Kinetic Energy ◽  
Impact Angle ◽  
Hypervelocity Impact ◽  
Impact Position ◽  
Debris Cloud ◽  
Combination Mode ◽  
The Impact ◽  
The Relationship ◽  
Aluminum Mesh

In order to study the fragmentation of projectile and ejection of debris clouds caused by hypervelocity impacting mesh bumper, simulation of aluminum sphere projectile hypervelocity normal impacting aluminum mesh bumper was practiced with SPH arithmetic of LS-DYNA soft. The diameter of projectile was 4mm. Impact velocities of aluminum spheres were varied between 2.2km/s and 6.2km/s. The impact angle was 0°. The relationship between the debris clouds characteristic of projectile and the impact position on aluminum mesh bumper was studied. The effect on fragmentation of projectile from different combination mode of aluminum mesh bumper was analyzed. The results showed that the morphologies of the debris cloud varied with the impact position when a projectile impacted the mesh bumper. The debris clouds as palpus was found, and some local kinetic energy concentrated appeared in the debris clouds. Debris clouds distribution was more uniform when projectile impacted wire across point on the mesh bumper. Debris clouds had more diffuse area and less residual kinetic energy when mesh bumper was combined with interleaving mode. Mesh bumper combined with interleaving mode was helpful in enhancing the protection performance of shields.

scholarly journals Technology of Manufacturing of Disk Blanks to High-Speed Elements for Tests on Anti-Meteoroid Protection

2020 ◽  
Vol 35 ◽  
pp. 04013
Author(s):  
Pavel V. Kruglov ◽  
Irina A. Bolotina
Keyword(s):  
Cross Section ◽  
High Speed ◽  
Peripheral Region ◽  
Circumferential Direction ◽  
Third Harmonic ◽  
The Third ◽  
The Cross ◽  
Different Thickness ◽  
Metal Blank ◽  
Periodic Profile

In this paper, a variant of the manufacturing technology of the disk blank for the segment liner of the shape charge is proposed. The charges are used to test the anti-meteorite stability of spacecraft. The proposed method makes it possible to form a blank in which, as its thickness decreases from the center to the periphery, a periodic profile variable in thickness is formed simultaneously in the circumferential direction. The disk metal blank is fixed in a three-cam chuck and the end face of the disk is cut with a decrease in thickness along the generatrix from the center to the periphery. Under the action of fastening forces, the disk blank is deformed and after processing the thickness in the cross section has a triangular periodic profile. Experiments on processing of disk preparations at various efforts of machine device are carried out. The dependences of the disc thickness on the fastening force in the device are obtained. After harmonic analysis of the thickness of the cross section, the values of the amplitudes of harmonics of different thickness in the circumferential direction at different distances from the center of the disk blank were determined. An increase in the fastening force leads to an increase in the amplitude of the third harmonic of the part thickness. It is shown that the change in the amplitudes of the first and second harmonics of different thickness is insignificant, and the amplitude of the third harmonic increases from the center to the periphery, which is caused by a decrease in the stiffness of the workpiece in the peripheral region.

Social and political dimension of stigmatization: The development of Natasha and Maria images for immigrants in Istanbul

2016 ◽  
Vol 13 (1) ◽  
pp. 159-168
Author(s):  
Bayram Unal
Keyword(s):  
Public Perception ◽  
Daily Life ◽  
Legal Framework ◽  
State Law ◽  
Migrant Women ◽  
Political Dimension ◽  
Security Forces ◽  
Official Discourse ◽  
The Third ◽  
The Impact

This study aims at understanding how the perceptions about migrants have been created and transferred into daily life as a stigmatization by means of public perception, media and state law implementations.  The focus would be briefly what kind of consequences these perceptions and stigmatization might lead. First section will examine the background of migration to Turkey briefly and make a summary of migration towards Turkey by 90s. Second section will briefly evaluate the preferential legal framework, which constitutes the base for official discourse differentiating the migrants and implementations of security forces that can be described as discriminatory. The third section deals with the impact of perceptions influential in both formation and reproduction of inclusive and exclusive practices towards migrant women. Additionally, impact of public perception in classifying the migrants and migratory processes would be dealt in this section.

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