scholarly journals Damage Analysis of Aluminium Foam Panel Subjected to Underwater Shock Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Xuan He ◽  
Ji-li Rong ◽  
Da-lin Xiang
Keyword(s):  
High Speed ◽  
Shock Loading ◽  
Shear Fracture ◽  
Test System ◽  
Aluminium Foam ◽  
Impact Speed ◽  
Time Deformation ◽  
Underwater Shock ◽  
Experiment Device ◽  
The Impact

Underwater shock loading experiment device is the equipment which simulates underwater explosive shock wave through experiment. Underwater shock loading experiment device was used to conduct high-speed underwater impact on aluminium foam panel and its damage modes were studied in this paper. 3D dynamic DIC test system was used to collect and analyze real-time deformation of target board. After the experiment was completed, a numerical simulation of the series of experiment was conducted through ABAQUS finite element simulation and then a comparative analysis of the experiment was implemented. To comprehensively study damage modes of aluminium foam panel subjected to underwater shock loading, damage modes of aluminium foam panel at different shock speeds were studied. Results indicated that when a certain impact speed which could damage aluminium foam panel was reached, if the impact speed was low, aluminium foam panel would generate shear fracture at constrained boundary of flange; if the impact speed was high, aluminium foam panel would firstly generate fracture at the center and then generate shear fracture at constrained boundary of flange, and central fracture would generate three cracks.

High-speed impacts of slender bodies into non-smooth, complex fluids

2018 ◽  
Vol 861 ◽  
Author(s):  
Ishan Sharma
Keyword(s):  
Penetration Depth ◽  
High Speed ◽  
Complex Fluids ◽  
Laboratory Data ◽  
Impact Speed ◽  
High Speed Impact ◽  
Smooth Complex ◽  
Theoretical Predictions ◽  
Slender Bodies ◽  
The Impact

We present a simple hydrodynamical model for the high-speed impact of slender bodies into frictional geomaterials such as soils and clays. We model these materials as non-smooth, complex fluids. Our model predicts the evolution of the impactor’s speed and the final penetration depth given the initial impact speed, and the material and geometric parameters of the impactor and the impacted material. As an application, we investigate the impact of deep-penetrating anchors into seabeds. Our theoretical predictions are found to match field and laboratory data very well.

Impact Energy Measurement of a Hydraulic Breaker

2006 ◽  
Vol 326-328 ◽  
pp. 1669-1672
Author(s):  
Jong Won Park ◽  
Hyoung Eui Kim
Keyword(s):  
Construction Industry ◽  
Impact Energy ◽  
High Speed ◽  
Test System ◽  
Hydraulic Power ◽  
Construction Machinery ◽  
Road Pavement ◽  
Hydraulic Cylinders ◽  
The Impact ◽  
Test Process

A hydraulic breaker for construction machinery generally used for the destroying and disassembling of buildings, crashing road pavement, breaking rocks at quarry and so on. So the measurement of the impact energy of a hydraulic breaker is very important thing to prove its capability to manufacturers and customers. In this study, the test system for measuring the impact energy of a hydraulic breaker was designed and constructed. The test system was consisted with hydraulic cylinders for mounting a breaker, impact absorbing base and frames, pressure and flow sensors, high speed and accurate data acquisition system diesel engine driven hydraulic power unit. The test process of the developed system was carried by measuring guide for tool energy rating for hydraulic breakers which was developed by the CIMA (Construction Industry Manufacturers Association) USA. The developed test system can be applied to measure the impact energy for various kinds of hydraulic breakers.

Basic Study on the Crushing of Frozen Soil by Shock Loading

2007 ◽  
Author(s):  
Toshiaki Watanabe ◽  
Hironori Maehara ◽  
Masahiko Otsuka ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
Shock Loading ◽  
Underwater Explosion ◽  
Frozen Soil ◽  
High Speed Camera ◽  
Underwater Shock Wave ◽  
Basic Study ◽  
Underwater Shock ◽  
A New Technique

The aim of study is to confirm a new technique that can crush the frozen soil and/or ice block using underwater shock wave generated by the underwater explosion of explosive. This technique can lead to the earlier sowing, which can have the larger harvest because the duration of sunshine increases. Especially, in Hokkaido prefecture, Japan, if the sowing is carried out in April, we can expect to have 150% of harvest in the ordinary season. This technique is effective against the cold regions. For example, Korea, China, Mongolia, Russia, Norway, and Sweden, etc. At first, we carried out experiments usung a detonating fuse and ice block. The process of ice breaking was observed by means of a high-speed camera. In order to check about that influence we tried to give an actual frozen soil a shock wave.

Experimental Study of Mouth Guards Response under Impact Loading

2011 ◽  
Vol 83 ◽  
pp. 78-84 ◽  
Author(s):  
Jean Luc Barou ◽  
Philippe Viot ◽  
Philippe Poisson
Keyword(s):  
High Speed ◽  
Shock Loading ◽  
Energy Analysis ◽  
Real Life ◽  
Dissipated Energy ◽  
High Speed Video ◽  
Mouth Guards ◽  
Dental Injuries ◽  
The Impact ◽  
Specific Impact

Mouthguard seems to be the best protection mean against dental injuries for sport application. The purpose of this study is to compare three different mouth guards under different condition of impacts closed to those observed on real-life shock loading. Specific devices were designed, firstly to pre-load and to form the mouthguard as it specified by the manufacturer; secondly to perform the different impacts on a very specific impact apparatus. Force and displacement were recorded as function of time. Those measurements were supplemented by a high speed video device to visualize the effect of the impact during the loading. A dissipated energy analysis was also performed.

Bubble entrapment during sphere impact onto quiescent liquid surfaces

2011 ◽  
Vol 680 ◽  
pp. 660-670 ◽  
Author(s):  
J. O. MARSTON ◽  
I. U. VAKARELSKI ◽  
S. T. THORODDSEN
Keyword(s):  
High Speed ◽  
Liquid Surface ◽  
Thin Sheet ◽  
Initial Contact ◽  
Liquid Density ◽  
Sphere Diameter ◽  
Impact Speed ◽  
Air Pocket ◽  
Quiescent Liquid ◽  
The Impact

We report observations of air bubble entrapment when a solid sphere impacts a quiescent liquid surface. Using high-speed imaging, we show that a small amount of air is entrapped at the bottom tip of the impacting sphere. This phenomenon is examined across a broad range of impact Reynolds numbers, 0.2 ≤ Re = (DU0/νl) ≤ 1.2 × 105. Initially, a thin air pocket is formed due to the lubrication pressure in the air layer between the sphere and the liquid surface. As the liquid surface deforms, the liquid contacts the sphere at a finite radius, producing a thin sheet of air which usually contracts to a nearly hemispherical bubble at the bottom tip of the sphere depending on the impact parameters and liquid properties. When a bubble is formed, the final bubble size increases slightly with the sphere diameter, decreases with impact speed but appears independent of liquid viscosity. In contrast, for the largest viscosities tested herein, the entrapped air remains in the form of a sheet, which subsequently deforms upon close approach to the base of the tank. The initial contact diameter is found to conform to scalings based on the gas Reynolds number whilst the initial thickness of the air pocket or ‘dimple’ scales with a Stokes' number incorporating the influence of the air viscosity, sphere diameter and impact speed and liquid density.

Springboard Droplet Bouncing on Flexible Superhydrophobic Substrates

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Patricia B. Weisensee ◽  
Junjiao Tian ◽  
Nenad Miljkovic ◽  
William P. King
Keyword(s):  
Natural Frequency ◽  
Contact Time ◽  
High Speed ◽  
Flexible Substrate ◽  
Superhydrophobic Surfaces ◽  
High Speed Imaging ◽  
Impact Speed ◽  
Lift Off ◽  
The Impact ◽  
Maximum Spreading

Droplet impact on rigid, superhydrophobic surfaces follows the well-known spreading, recoil, and lift-off behavior at lower impact speeds (a), and splashing at higher impact speeds (b). The contact time tc of these bouncing droplets is independent of the impact speed, and difficult to control. Using high speed imaging (9500 fps) of water droplets impacting superhydrophobic substrates with stiffness 0.5 to 7630 N/m (rigid), we were able to show that substrate flexibility can reduce contact times. Upon impact on a flexible substrate, the droplet excites the substrate to oscillate at the membrane or cantilever natural frequency (d). The oscillation accelerates the droplet upwards, initiating early droplet lift-off at the edges of the droplet close to the point of maximum spreading (c). Droplets fully lift off before fully recoiling, i.e. in a pancake shape. We call this phenomenon the springboard effect. Contact times are reduced by up to 50% compared to rigid substrates.

Impact Wear Resistance of Nanocomposite Coatings for Aircraft Components

2019 ◽  
Vol 813 ◽  
pp. 387-392 ◽  
Author(s):  
Giovanna Gautier ◽  
Maria Giulia Faga ◽  
Vincenzo Tebaldo
Keyword(s):  
High Speed ◽  
Erosion Resistance ◽  
High Speed Steel ◽  
Ceramic Coatings ◽  
Landing Gear ◽  
Erosion Wear ◽  
Test Volume ◽  
Impact Speed ◽  
Structural Part ◽  
The Impact

Landing gear is an aircraft component often subjected to wear, fracture, mechanical failure and erosion, principally caused by impact with sand and other small particles. Erosion wear can cause deformation and material removal with consequent efficiency reduction. Coatings can protect stressed structural part and impede the erosion of the metallic components. This work focus on the investigation of the erosion resistance of two ceramic multilayer coatings, AlSiTiN and AlSiCrN, deposited by Physical Vapour Deposition (PVD) on a high speed steel (H11) usually used for landing gear application. Erosion test were carried out with an erosion machine using alumina particles. Powder was directed to the specimens (coatings and substrate) at nominal impingement angles of 90° and 20° with different impact speed (50, 75, 100 and 125 m/s at 90° and 100, 125, 150 and 175 m/s at 20°), at a nozzle-specimen distance of 10 mm. All the tests were performed for two minutes. Hardness and Young's modulus were obtained by nanoindentation, and adhesion between coating and substrate was evaluated by scratch test. Volume lost was measured with Taylor Hobson profiler while cracking behaviour and microstructure modifications were examined with a scanning electron microscope (SEM). AlSiCrN coating significantly enhanced the erosion resistance of H11 substrate, showing higher resistance also with respect to AlSiTiN coating. Indeed, the coating was not completely removed from the surface neither at 90° nor at 20°. The erosion wear rapidly increased by increasing the impact speed in the case of substrate and AlSiTiN, while such parameter was not significantly influent in the case of AlSiCrN. The results suggest that adhesion should play an important role to explain the highest erosion resistance of AlSiCrN coating. Erosion mechanism was principally driven by the intrinsic brittleness of both ceramic coatings.

scholarly journals Study on Behind Helmet Blunt Trauma Caused by High-Speed Bullet

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhihua Cai ◽  
Xingyuan Huang ◽  
Yun Xia ◽  
Guibing Li ◽  
Zhuangqing Fan
Keyword(s):  
Brain Tissue ◽  
Blunt Trauma ◽  
Dura Mater ◽  
High Speed ◽  
Optimization Design ◽  
Reference Value ◽  
Element Model ◽  
Impact Speed ◽  
The Impact ◽  
The Brain

The mechanism of Behind Helmet Blunt Trauma (BHBT) caused by a high-speed bullet is difficult to understand. At present, there is still a lack of corresponding parameters and test methods to evaluate this damage effectively. The purpose of the current study is therefore to investigate the response of the human skull and brain tissue under the loading of a bullet impacting a bullet-proof helmet, with the effects of impact direction, impact speed, and impactor structure being considered. A human brain finite element model which can accurately reconstruct the anatomical structures of the scalp, skull, brain tissue, etc., and can realistically reflect the biomechanical response of the brain under high impact speed was employed in this study. The responses of Back Face Deformation (BFD), brain displacement, skull stress, and dura mater pressure were extracted from simulations as the parameters reflecting BHBT risk, and the relationships between BHBT and bullet-proof equipment structure and performance were also investigated. The simulation results show that the frontal impact of the skull produces the largest amount of BFD, and when the impact directions are from the side, the skull stress is about twice higher than other directions. As the impact velocity increases, BFD, brain displacement, skull stress, and dura mater pressure increase. The brain damage caused by different structural bullet bodies is different under the condition of the same kinetic energy. The skull stress caused by the handgun bullet is the largest. The findings indicate that when a bullet impacts on the bullet-proof helmet, it has a higher probability of causing brain displacement and intracranial high pressure. The research results can provide a reference value for helmet optimization design and antielasticity evaluation and provide the theoretical basis for protection and rescue.

scholarly journals Determining the Velocity of Hypersonic Compact Elements in Ground Testing Plants

2019 ◽  
pp. 65-72
Author(s):  
S.I. Gerasimov ◽  
I.A. Odzeriho ◽  
R.V. Gerasimova ◽  
B.A. Yanenko
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
Shock Loading ◽  
Experimental Testing ◽  
Complex Structures ◽  
Ground Testing ◽  
High Speed Impact ◽  
Condensed Explosives ◽  
Hypersonic Speeds ◽  
The Impact

Protection of spacecraft from high-speed impact when encountering meteorite particles and man-made debris is currently a pressing issue. This article presents methods for determining the reaction of complex structures to the impact of particles with cosmic velocities. To determine the anti-meteorite resistance of materials and structures and to study the reaction of materials under high-intensity shock loading, schemes are developed for the production and registration of high-speed metal compact elements moving at hypersonic speeds using cumulative explosive throwing devices based on high-power condensed explosives. The use of the ‘hemisphere-cylinder’ shaped lining made it possible to test a shaped charge, consistently forming a steel compact element with a velocity of 6 km/s. The paper presents the results of numerical calculations and experimental testing of such a booster. Using this device, a method for determining the speed of the hypersonic striker pin is developed based on visualization of the head shock wave at the entrance of the striker into water.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

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