scholarly journals Hypervelocity Impact Cratering on Semi-Infinite Concrete Targets of Projectiles with Different Length to Diameter Ratios

2020 ◽  
Vol 10 (11) ◽  
pp. 3910 ◽  
Author(s):  
Yangyu Lu ◽  
Qingming Zhang ◽  
Yijiang Xue ◽  
Cheng Shang ◽  
Wenjin Liu ◽  
...  
Keyword(s):  
Empirical Formula ◽  
Scaling Laws ◽  
Predictive Ability ◽  
Hypervelocity Impact ◽  
Target Chamber ◽  
Impact Cratering ◽  
Fragment Mass ◽  
Stage Combustion ◽  
Crater Volume ◽  
The Impact

Impact cratering experiments were performed on semi-infinite concrete targets with 7 mm-diameter 40CrNiMo steel long-rod projectiles at impact velocities ranging from 2117 m/s to 3086 m/s by using a two-stage combustion light-gas gun. After the impact experiments, the crater diameter and depth as well as the crater volume were carefully measured. The concrete fragments were collected from the target chamber and the fragment mass was measured. The size of the crater (including the volume, diameter, and depth) and the fragment mass increased with increasing impact velocities, while the fragment distributions at different impact velocities were almost the same. Scaling laws for the crater volume impacted by the rod-shaped projectile were discussed and an empirical formula of crater volume was determined by the experimental data from the literature. Through the verification of the present experimental results, the predictive ability of the empirical formula proved to be reliable. Scaling laws for the size distribution of concrete fragments were also discussed. The normalized fragment mass distribution was proportional to the impact velocity raised to the power 1.5.

Splash formation by spherical drops

2001 ◽  
Vol 427 ◽  
pp. 73-105 ◽  
Author(s):  
LIOW JONG LENG
Keyword(s):  
High Resolution ◽  
Quantitative Data ◽  
Water Surface ◽  
High Speed ◽  
Scaling Laws ◽  
Capillary Wave ◽  
Water Drop ◽  
Qualitative And Quantitative ◽  
High Resolution Images ◽  
The Impact

The impact of a spherical water drop onto a water surface has been studied experimentally with the aid of a 35 mm drum camera giving high-resolution images that provided qualitative and quantitative data on the phenomena. Scaling laws for the time to reach maximum cavity sizes have been derived and provide a good fit to the experimental results. Transitions between the regimes for coalescence-only, the formation of a high-speed jet and bubble entrapment have been delineated. The high-speed jet was found to occur without bubble entrapment. This was caused by the rapid retraction of the trough formed by a capillary wave converging to the centre of the cavity base. The converging capillary wave has a profile similar to a Crapper wave. A plot showing the different regimes of cavity and impact drop behaviour in the Weber–Froude number-plane has been constructed for Fr and We less than 1000.

scholarly journals Hydrodynamic Ram Effect Caused by Debris Hypervelocity Impact on Satellite Tank

2019 ◽  
Vol 9 (20) ◽  
pp. 4200 ◽  
Author(s):  
Beilei Zhao ◽  
Jiguang Zhao ◽  
Cunyan Cui ◽  
Yongsheng Duan
Keyword(s):  
Shock Wave ◽  
Angular Velocity ◽  
Hypervelocity Impact ◽  
Filling Ratio ◽  
Maximum Diameter ◽  
Residual Velocity ◽  
Hydrodynamic Ram ◽  
Ram Effect ◽  
The Impact ◽  
Bulge Height

To study the hydrodynamic ram effect caused by the debris hypervelocity impact on the satellite tank, a numerical simulation of the spherical debris impacting the satellite tank at the velocity of 7000 m/s was carried out based on ANSYS/LS-DYNA software. The attenuation law of debris velocity, the propagation process of the shock wave and the deformation of the tank walls were investigated. The influences of the liquid-filling ratio, the magnitude, and direction of angular velocity on the hydrodynamic ram effect were analyzed. Results show that the debris velocity decreased rapidly and the residual velocity was 263 m/s when the debris passed through the tank. The shock wave was hemispherical, and the pressure of shock wave was the smallest at the element with an angle of 90° to the impact line. The maximum diameter of the front perforation was larger than that of the back perforation and the bulge height on the front wall was smaller than that on the back wall. With the decrease of the liquid-filling ratio, the diameter of the perforations and bulge height decreased. When the debris impacted the satellite tank with the angular velocity in the x direction, the debris trajectory did not deflect. When the debris impacted the satellite tank with the angular velocities in the y and z direction, the debris trajectory deflected to the negative direction of the z axis and y axis, respectively. The magnitude of the angular velocity affects the residual velocity of debris and the diameter of perforations.

Modeling Hypervelocity Impacts Using Smoothed Particle Hydrodynamics

2018 ◽  
Author(s):  
M. Ganser ◽  
B. van der Linden ◽  
C. G. Giannopapa
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Large Deformations ◽  
Hypervelocity Impact ◽  
Density Fluctuations ◽  
Computational Domain ◽  
Simulation Tool ◽  
Hypervelocity Impacts ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
The Impact

Hypervelocity impacts occur in outer space where debris and micrometeorites with a velocity of 2 km/s endanger spacecraft and satellites. A proper shield design, e.g. a laminated structure, is necessary to increase the protection capabilities. High velocities result in massive damages. The resulting large deformations can hardly be tackled with mesh based discretization methods. Smoothed Particle Hydrodynamics (SPH), a Lagrangian meshless scheme, can resolve large topological changes whereas it still follows the continuous formulation. Derived by variational principles, SPH is able to capture large density fluctuations associated with hypervelocity impacts correctly. Although the impact region is locally limited, a much bigger domain has to be discretized because of strong outgoing pressure waves. A truncation of the computational domain is preferable to save computational power, but this leads to artificial reflections which influence the real physics. In this paper, hypervelocity impact (HVI) is modelled by means of basic conservation assumptions leading to the Euler equations of fluid dynamics accompanied by the Mie-Grueneisen equation of state. The newly developed simulation tool SPHlab presented in this work utilizes the discretization method smoothed particle hydrodynamics (SPH) to capture large deformations. The model is validated through a number of test cases. Different approaches are presented for non-reflecting boundaries in order to tackle artificial reflections on a computational truncated domain. To simulate an HVI, the leading continuous equations are derived and the simulation tool SPHlab is developed. The method of characteristics allows to define proper boundary fluxes by removing the inwards travelling information. One- and two-dimensional model problems are examined which show excellent absorption behaviour. An hypervelocity impact into a laminated shield is simulated and analysed and a simple damage model is introduced to model a spallation failure mode.

Transitional impact craters on the Moon: Insight into the effect of target lithology on the impact cratering process

2018 ◽  
Author(s):  
Gordon R. Osinski ◽  
Elizabeth A. Silber ◽  
Jacqueline Clayton ◽  
Richard A. F. Grieve ◽  
Kayle Hansen ◽  
...  
Keyword(s):  
Impact Craters ◽  
The Moon ◽  
Impact Cratering ◽  
The Impact ◽  
Insight Into

Investigation into Damage of Stainless Steel Mesh/ALPlate Multi-Shock Shield under Hypervelocity AL-Spheres Impact

2012 ◽  
Vol 525-526 ◽  
pp. 397-400
Author(s):  
Gong Shun Guan ◽  
Dong Dong Pu ◽  
Yue Ha
Keyword(s):  
Stainless Steel ◽  
Impact Angle ◽  
Separation Distance ◽  
Hypervelocity Impact ◽  
Aluminum Plate ◽  
Optimized Design ◽  
Stainless Steel Mesh ◽  
Steel Mesh ◽  
Gas Gun ◽  
The Impact

A series of hypervelocity impact tests on stainless steel mesh/aluminum plate multi-shock shield were practiced with a two-stage light gas gun facility. Impact velocity was approximately 4km/s. The diameter of projectiles was 6.4mm. The impact angle was 0°. The fragmentation and dispersal of hypervelocity particle against stainless steel mesh bumper varying with mesh opening size and the wire diameter were investigated. It was found that the mesh wall position, diameter of wire, separation distance arrangement and mesh opening had high influence on the hypervelocity impact characteristic of stainless steel mesh/aluminum plate multi-shock shields. When the stainless steel mesh wall was located in the first wall site of the bumper it did not help comminuting and decelerating projectile. When the stainless steel mesh wall was located in the last wall site of the bumper, it could help dispersing debris clouds, reducing the damage of the rear wall. Optimized design idea of stainless steel mesh/aluminum plate multi-shock shields was suggested.

Analysis of hypervelocity impacts: The tungsten case

2021 ◽  
Author(s):  
A Fraile ◽  
Prashant Dwivedi ◽  
Giovanni Bonny ◽  
Tomas Polcar
Keyword(s):  
Kinetic Energy ◽  
Interatomic Potential ◽  
Detailed Examination ◽  
Penetration Process ◽  
Damage Initiation ◽  
Crater Size ◽  
Crater Volume ◽  
Parallel Molecular Dynamics ◽  
Dynamics Simulations ◽  
The Impact

Abstract The atomistic mechanisms of damage initiation during high velocity (v up to 9 km/s, kinetic energies up to 200 keV) impacts of W projectiles on a W surface have been investigated using parallel molecular-dynamics simulations involving large samples (up to 40 million atoms). Various aspects of the impact at high velocities, where the projectile and part of the target materials undergo massive plastic deformation, breakup, melting, and vaporization, are analyzed. Different stages of the penetration process have been identified through a detailed examination of implantation, crater size and volume, sputtered atoms, and dislocations created by the impacts. The crater volume increases linearly with the kinetic energy for a given impactor; and the total dislocation length increases with the kinetic energy but depends itself on the size of the impactor. Furthermore, the total dislocation length is less dependent of the fine details of the interatomic potential. The results are rationalized based on the physical properties of bcc W.

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.

scholarly journals Cratering for Impact of Hypervelocity Projectiles into Granite Targets within a Velocity Range of 1.91–3.99 km/s: Experiments and Analysis

2020 ◽  
Vol 10 (4) ◽  
pp. 1393
Author(s):  
Xiaofeng Wang ◽  
Jingbo Liu ◽  
Biao Wu ◽  
Defeng Kong ◽  
Jiarong Huang ◽  
...  
Keyword(s):  
Impact Velocity ◽  
Scaling Law ◽  
Density Ratio ◽  
Hypervelocity Impact ◽  
Experimental Results ◽  
Tungsten Alloy ◽  
Regression Equations ◽  
Velocity Range ◽  
Predicted Values ◽  
The Impact

To understand and analyze crater damage of rocks under hypervelocity impact, the hypervelocity impact cratering of 15 shots of hemispherical-nosed cylindrical projectiles into granite targets was studied within the impact velocity range of 1.91–3.99 km/s. The mass of each projectile was 40 g, and the length–diameter ratio was 2. Three types of metal material were adopted for the projectiles, including titanium alloy with a density of 4.44 g/cm3, steel alloy with a density of 7.81 g/cm3, and tungsten alloy with a density of 17.78 g/cm3. The projectile–target density ratio (ρp/ρt) ranged from 1.71 to 6.86. The depth–diameter ratios (H/D) of the craters yielded from the experiments were between 0.14 and 0.24. The effects of ρp/ρt and the impact velocity on the morphologies of the crater were evaluated. According to the experimental results, H/D of craters is negatively correlated with the impact velocity, whereas the correlation between H/D and ρp/ρt is weak positive. The crater parameters were expressed as power law relations of impact parameters by using scaling law analysis. The multiple regression analysis was utilized to obtain the coefficients and the exponents of the relation equations. The predicted values of the regression equations were close to the experimental results.

scholarly journals Applying the Metafounders Approach for Genomic Evaluation in a Multibreed Beef Cattle Population

2020 ◽  
Vol 11 ◽  
Author(s):  
Vinícius Silva Junqueira ◽  
Paulo Sávio Lopes ◽  
Daniela Lourenco ◽  
Fabyano Fonseca e Silva ◽  
Fernando Flores Cardoso
Keyword(s):  
Beef Cattle ◽  
Variance Components ◽  
Genetic Relationships ◽  
A Priori ◽  
Predictive Ability ◽  
Single Step ◽  
Pedigree Information ◽  
Phenotypic Variance ◽  
Genomic Information ◽  
The Impact

Pedigree information is incomplete by nature and commonly not well-established because many of the genetic ties are not known a priori or can be wrong. The genomic era brought new opportunities to assess relationships between individuals. However, when pedigree and genomic information are used simultaneously, which is the case of single-step genomic BLUP (ssGBLUP), defining the genetic base is still a challenge. One alternative to overcome this challenge is to use metafounders, which are pseudo-individuals that describe the genetic relationship between the base population individuals. The purpose of this study was to evaluate the impact of metafounders on the estimation of breeding values for tick resistance under ssGBLUP for a multibreed population composed by Hereford, Braford, and Zebu animals. Three different scenarios were studied: pedigree-based model (BLUP), ssGBLUP, and ssGBLUP with metafounders (ssGBLUPm). In ssGBLUPm, a total of four different metafounders based on breed of origin (i.e., Hereford, Braford, Zebu, and unknown) were included for the animals with missing parents. The relationship coefficient between metafounders was in average 0.54 (ranging from 0.34 to 0.96) suggesting an overlap between ancestor populations. The estimates of metafounder relationships indicate that Hereford and Zebu breeds have a possible common ancestral relationship. Inbreeding coefficients calculated following the metafounder approach had less negative values, suggesting that ancestral populations were large enough and that gametes inherited from the historical population were not identical. Variance components were estimated based on ssGBLUPm, ssGBLUP, and BLUP, but the values from ssGBLUPm were scaled to provide a fair comparison with estimates from the other two models. In general, additive, residual, and phenotypic variance components in the Hereford population were smaller than in Braford across different models. The addition of genomic information increased heritability for Hereford, possibly because of improved genetic relationships. As expected, genomic models had greater predictive ability, with an additional gain for ssGBLUPm over ssGBLUP. The increase in predictive ability was greater for Herefords. Our results show the potential of using metafounders to increase accuracy of GEBV, and therefore, the rate of genetic gain in beef cattle populations with partial levels of missing pedigree information.

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