scholarly journals Axial Force Coefficient of APFSDS Projectile

2020 ◽  
Vol 1 ◽  
pp. 1-15
Author(s):  
Ammar Trakic
Keyword(s):  
Kinetic Energy ◽  
Impact Velocity ◽  
Axial Force ◽  
High Impact ◽  
Cfd Model ◽  
Force Coefficient ◽  
Terminal Ballistics ◽  
High Impact Velocity ◽  
The World ◽  
The Impact

Armor-piercing ammunition is primarily used to combat against heavy armored targets (tanks), but targets can be light armored vehicles, aircraft, warehouse, structures, etc. It has been shown that the most effective type of anti-tank ammunition in the world is the APFSDS ammunition (Armor Piercing Fin Stabilized Discarding Sabot). The APFSDS projectile flies to the target and with his kinetic energy acts on the target, that is, penetrates through armor and disables the tank and his crew. Since the projectile destroys target with his kinetic energy, then it is necessary for the projectile to have the high impact velocity. The decrease in the velocity of a projectile, during flight, is mainly influenced by aerodynamic forces. The most dominant is the axial force due to the laid trajectory of the projectile. By knowing the axial force (axial force coefficient), it is possible to predict the impact velocity of the projectile, by external ballistic calculation, in function of the distance of the target, and to define the maximum effective range from the aspect of terminal ballistics. In this paper two models will be presented for predicting axial force (the axial force coefficient) of an APFSDS projectile after discarding sabot. The first model is defined in STANAG 4655 Ed.1. This model is used to predict the axial force coefficient for all types of conventional projectiles. The second model for predicting the axial force coefficient of an APFSDS projectile, which is presented in the paper, is the CFD-model (Computed Fluid Dynamics).

Effect of Timing and Velocity of Impact on Ventricular Myocardial Rupture

1983 ◽  
Vol 105 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Ian V. Lau
Keyword(s):  
Impact Velocity ◽  
High Speed ◽  
Left Ventricular ◽  
High Impact ◽  
Muscle Stiffness ◽  
Cardiac Rupture ◽  
Myocardial Wall ◽  
High Impact Velocity ◽  
Myocardial Rupture ◽  
The Impact

The effects of impact timing during the cardiac cycle on the sensitivity of the heart to impact-induced rupture was investigated in an open-chest animal model. Direct mechanical impacts were applied to two adjacent sites on the exposed left ventricular surface at the end of systole or diastole. Impacts at 5 m/s and a contact stroke of 5 cm at the end of systole resulted in no cardiac rupture in seven animals, whereas similar impacts at the end of diastole resulted in six cardiac ruptures. Direct impact at 15 m/s and a contact stroke of 2 cm at the end of either systole or diastole resulted in perforationlike cardiac rupture in all attempts. At low-impact velocity the heart was observed in high-speed movie to bounce away from the impact interface during a systolic impact, but deform around the impactor during a diastolic impact. The heart generally remained motionless during the downward impact stroke at high-impact velocity in either a systolic or diastolic impact. The lower ventricular pressure, reduced muscle stiffness, thinner myocardial wall and larger mass of the filled ventricle probably contributed to a greater sensitivity of the heart to rupture in diastole at low-impact velocity. However, the same factors had no role at high-impact velocity.

Selection of Densification Strain to Predict Dynamic Crushing Stress at High Impact Velocity of ALPORAS Aluminium Foam

2014 ◽  
Vol 626 ◽  
pp. 383-388 ◽  
Author(s):  
Mohd Azman Yahaya ◽  
Dong Ruan ◽  
Guo Xing Lu ◽  
Matthew S. Dargusch ◽  
Tong Xi Yu
Keyword(s):  
Impact Velocity ◽  
Strain Curve ◽  
High Impact ◽  
Aluminium Foam ◽  
Gas Gun ◽  
High Impact Velocity ◽  
Velocity Prediction ◽  
Blast Loadings ◽  
The Impact ◽  
Dynamic Crushing

Cellular material such as aluminium foam has been considered as a potential material for energy absorption upon impact and blast loadings. One of the most important properties that contribute to this feature is the densification strain. At high impact velocity, prediction of the densification strain from quasi-static engineering stress-strain curve has been found inadequate. Furthermore, theoretical prediction using the equation proposed by Reid et al. always over-predicts the dynamic crushing stress. Formation of the shock wave at high impact velocity is believed to further increase the densification level of the foam. However, this effect is disregarded when determining the densification strain quasi-statically. The present study aims to address this issue by determining the densification strain experimentally from impact tests. Forty cylindrical aluminium foams with three different lengths were used as projectiles and were fired towards a rigid load cell by using a gas gun. The peak forces generated from the impact were recorded and analysed. The experimental densification strains were determined physically by measuring the deformation of the foam projectiles after the tests. It is concluded that, at high impact velocity, the densification strain varies with the initial impact velocity. Therefore an appropriate value of densification strain needs to be used in the equation of dynamic crushing stress for a better approximation.

scholarly journals Drone Launched Short Range Rockets

Aerospace ◽  
2020 ◽  
Vol 7 (6) ◽  
pp. 76
Author(s):  
Mikhail V. Shubov
Keyword(s):  
High Altitude ◽  
Impact Velocity ◽  
Initial Velocity ◽  
Short Range ◽  
Thermal Protection ◽  
High Impact ◽  
High Impact Velocity

A concept of drone launched short range rockets (DLSRR) is presented. A drone or an aircraft rises DLSRR to a release altitude of up to 20 km. At the release altitude, the drone or an aircraft is moving at a velocity of up to 700 m/s and a steep angle of up to 68° to the horizontal. After DLSRRs are released, their motors start firing. DLSRRs use slow burning motors to gain altitude and velocity. At the apogee of their flight, DLSRRs release projectiles which fly to the target and strike it at high impact velocity. The projectiles reach a target at ranges of up to 442 km and impact velocities up to 1.88 km/s. We show that a rocket launched at high altitude and high initial velocity does not need expensive thermal protection to survive ascent. Delivery of munitions to target by DLSRRs should be much less expensive than delivery by a conventional rocket. Even though delivery of munitions by bomber aircraft is even less expensive, a bomber needs to fly close to the target, while a DLSRR carrier releases the rockets from a distance of at least 200 km from the target. All parameters of DLSRRs, and their trajectories are calculated based on theoretical (mechanical and thermodynamical) analysis and on several MatLab programs.

High impact velocity on multi-layered composite of polyether ether ketone and aluminium

2015 ◽  
Vol 22 (8) ◽  
pp. 705-715 ◽  
Author(s):  
D. García-González ◽  
M. Rodríguez-Millán ◽  
A. Vaz-Romero ◽  
A. Arias
Keyword(s):  
Impact Velocity ◽  
Layered Composite ◽  
High Impact ◽  
Polyether Ether Ketone ◽  
High Impact Velocity ◽  
Ether Ketone

ANALYSIS OF THE WATER IMPACT OF SYMMETRIC WEDGES WITH A MULTI- MATERIAL EULERIAN FORMULATION

2021 ◽  
Vol 154 (A4) ◽  
Author(s):  
S Wang ◽  
C Guedes Soares
Keyword(s):  
Pressure Distribution ◽  
Impact Velocity ◽  
Pressure Coefficient ◽  
Time History ◽  
Maximum Pressure ◽  
Vertical Force ◽  
Force Coefficient ◽  
Explicit Finite Element ◽  
Eulerian Formulation ◽  
The Impact

The two-dimensional hydrodynamic problem of a symmetric wedge vertically impacting in calm water is analysed by using an explicit finite element method based on a multi-material Eulerian formulation. The slam-induced loads on wedges with different deadrise angle at a constant velocity are calculated, including pressure distribution, maximum pressure coefficient, force coefficient and time history of vertical force, which are compared with available theoretical and analytical results. The time evolution of pressure distribution and free surface elevation are presented. Furthermore, the effects of impact velocity are investigated. It shows that this method is capable of predicting the local slamming loads, and as well assessing the effects of the deadrise angle and the impact velocity on the slamming pressure for the wedge-shape section.

Advanced Pipeline Impact Design

2016 ◽  
Author(s):  
Ragnar T. Igland ◽  
Hagbart S. Alsos ◽  
Stig Olav Kvarme
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Impact Velocity ◽  
Large Diameter ◽  
Small Diameter ◽  
Energy Estimates ◽  
Dissipated Energy ◽  
Accurate Information ◽  
Cross Sectional ◽  
The Impact

The safety of pipelines and subsea structures are key elements in subsea field developments. As part of the safety engineering, protection from dropped objects and third party impact actions is required. This article addresses this aspect. Dropped object from a platform or a vessel is one of the design scenarios. The fall-pattern of the object is essential for the impact velocity and corresponding energy, model of the path and the effects of hydrodynamic behavior is outlined. In lieu of accurate information, the design code use energy band for energy estimates and may give extremely conservative impact energy. The falling objects structural flexibility and properties are discussed and evaluated regarding the energy dissipation and possible damage of the pipeline. The pipeline combined response from global deflection and denting regarding impacts are investigated. Analysis and testing methods applied in pipeline design are presented. Focus is placed on the overall interaction between the impacting object, the deformed pipeline and energy dissipation by coating and soil. Typically, pipeline damage from design codes provides conservative cross sectional damage estimates. This is confirmed from both simplified and detailed FE analyses, as well as fullscale impact experiments performed by REINERTSEN AS. One of the main objectives promoted by the authors is the importance of both impact velocity and mass during impact, and not only the kinetic energy of the impact. The kinetic energy from a dropped object is unlikely to be fully dissipated as cross sectional deformation of the pipeline. Global deformations will be triggered, which implies that the dissipated energy going into local denting is reduced to a fractional value. The effect is more pronounced for small diameter pipelines than for pipelines with large diameter. This paper discusses the impact mechanics and seeks to estimate the fractional value by using simplified element analysis.

scholarly journals Universal rescaling of drop impact on smooth and rough surfaces

2015 ◽  
Vol 786 ◽  
Author(s):  
J. B. Lee ◽  
N. Laan ◽  
K. G. de Bruin ◽  
G. Skantzaris ◽  
N. Shahidzadeh ◽  
...  
Keyword(s):  
Contact Angle ◽  
Impact Velocity ◽  
Rough Surfaces ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
High Impact ◽  
Low Velocity ◽  
Zero Velocity ◽  
High Impact Velocity ◽  
Maximum Spreading

The maximum spreading of drops impacting on smooth and rough surfaces is measured from low to high impact velocity for liquids with different surface tensions and viscosities. We demonstrate that dynamic wetting plays an important role in the spreading at low velocity, characterized by the dynamic contact angle at maximum spreading. In the energy balance, we account for the dynamic wettability by introducing the capillary energy at zero impact velocity, which relates to the spreading ratio at zero impact velocity. Correcting the measured spreading ratio by the spreading ratio at zero velocity, we find a correct scaling behaviour for low and high impact velocity and, by interpolation between the two, we find a universal scaling curve. The influence of the liquid as well as the nature and roughness of the surface are taken into account properly by rescaling with the spreading ratio at zero velocity, which, as demonstrated, is equivalent to accounting for the dynamic contact angle.

Experimental study of spreading characteristics of droplet impacting on canopy fabric surface

2017 ◽  
Vol 31 (34) ◽  
pp. 1750325 ◽  
Author(s):  
Han Cheng ◽  
Chao Qiu ◽  
Changchun Zhou ◽  
Xuebin Sun ◽  
Rui Yang
Keyword(s):  
Experimental Study ◽  
Kinetic Energy ◽  
Impact Velocity ◽  
Working Conditions ◽  
Experimental Results ◽  
Initial Kinetic Energy ◽  
Droplet Spreading ◽  
Visualization Technology ◽  
Fabric Surface ◽  
The Impact

A new experiment based on visualization technology is designed to study the spreading characteristics of droplet impacting on canopy fabric. The processes of droplet impacting on 66 type polyamide grid silk are captured. The experimental results show that the spreading characteristics are also affected by fabric pretension and fabric permeability. The pretension is favorable for the droplet to reach the final equilibrium stage. The impact velocity determines the initial kinetic energy and plays a major role in the droplet spreading. The fabric permeability determines the wettability and has different effects on spreading characteristics under different working conditions. In addition, the above factors can enhance the two competitive processes of spreading and imbibing at the same time. The spreading characteristics depend on which process is the dominant one.

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