scholarly journals Numerical and Experimental Studies of the ŁK Type Shaped Charge

2020 ◽  
Vol 10 (19) ◽  
pp. 6742 ◽  
Author(s):  
Dariusz Pyka ◽  
Adam Kurzawa ◽  
Miroslaw Bocian ◽  
Marcin Bajkowski ◽  
Mariusz Magier ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Design Parameters ◽  
Simulation Studies ◽  
Initiation System ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
The Impact ◽  
Positive Effect ◽  
Explosive Detonation

In this paper, the authors presented an analysis of the strengthening of the cumulative jet by the appropriate formation of the detonation wave front acting under the influence of high pressure on the liner. The analysis of the Polish ŁK cumulative charge was carried out using numerical methods in the ABAQUS program. Simulation studies were carried out on axial and peripheral initiations of the explosive cumulative liner. For this purpose, two types of cumulative charges were made with the same design parameters, differing only in the explosive detonation-initiation system. The impact of the elastomer insert on the focusing of the cumulative jet was verified. The influence of peripheral and axial initiation on a cumulative jet’s velocity was investigated. The authors proposed a new conical insert placed in the explosive between the pocket for the detonator and the liner, also changing the material of the cumulative liner. The smoothed-particle hydrodynamics method was used to describe the formation of a cumulative jet. The obtained results were verified experimentally, and they show that modification of the ŁK charge has a positive effect on jet amplification, with an inevitable collapse in the final stage of formation. The obtained results correlate with the literature’s data.

Numerical study on debris flow in step-pools channel using smoothed particle hydrodynamics method

2020 ◽  
Author(s):  
Shuai Li ◽  
Xiaoqing Chen ◽  
Chong Peng ◽  
Jiangang Chen
Keyword(s):  
Debris Flow ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Impact Force ◽  
Numerical Study ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
The Impact ◽  
Peak Impact Force

<p>Drainage channel with step-pool systems are widely used to control debris flow. However, the blocking of debris flow often gives rise to local damage at the steps and baffles. Hence, the estimation of impact force of debris flow is crucial for design step-pools channel. This paper presents a numerical study on the impact behavior of debris flows using SPH (Smoothed Particle Hydrodynamics) method. Some important parameters, such as the baffle shape (square, triangle, and trapezoid) and the densities of debris flows are considered to examine their influence on the impact force. The results show that the largest peak impact force is obtained at the second last baffle, rather than the first baffle. Moreover, the square baffle gives rise to the largest impact force whereas the triangle baffle bears the smallest one among the three baffles. Generally, the peak impact force increases with increasing the inflow density. However, a threshold density, beyond which the peak impact force will decrease, is suggested by the simulations. Based on the numerical results, an improved expression to predict the impact force considering the inclined angle of baffle is proposed.</p>

scholarly journals Экспериментально-расчетное исследование высокоскоростного соударения алюминиевого ударника со сплошной и сетчатой преградой

2019 ◽  
Vol 89 (8) ◽  
pp. 1213
Author(s):  
В.А. Кузьмин ◽  
С.И. Герасимов ◽  
А.В. Зубанков ◽  
А.Г. Сироткина ◽  
Е.П. Акашева ◽  
...  
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Recording Equipment ◽  
High Speed Video Camera ◽  
Start Up ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
Analysis Of Results ◽  
The Impact

The results of the computational and experimental study of the features of the impact of the impactor with the barrier simulating the screen shield of the spacecraft are presented, the pictures of fragmentation of the impactor and the barrier are presented. Numerical calculations were performed using the SPH (Smoothed Particle Hydrodynamics) method. In the experiment, the impactor was accelerated using a two-stage light-gas gun, the state of the barrier and the impactor at the time of their interaction was controlled using x-ray and high-speed video camera. Start-up of the recording equipment was carried out by means of induction sections. The comparative analysis of results of numerical calculation and experiment is given.

SPH SIMULATIONS OF HYPERVELOCITY IMPACT OF AL SPHERES ON MULTI-PLATE STRUCTURES

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1604-1611 ◽  
Author(s):  
QING-MING ZHANG ◽  
REN-RONG LONG ◽  
ZHI-FANG LIU ◽  
FENG-LEI HUANG
Keyword(s):  
Hypervelocity Impact ◽  
Plate Structures ◽  
Promising Alternative ◽  
Single Plate ◽  
Morphologic Characteristics ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
The Impact ◽  
Shield Design

A series of numerical simulations using SPH (Smoothed Particle Hydrodynamics) method were carried out to study the hypervelocity impact of aluminum spheres on multi-plate structures. Both the morphologic characteristics of debris clouds and the damage of intermediate plates were investigated. The possible damage effects of debris cloud threat on back wall were also described qualitatively. Results showed that, comparing with single plate or double-plate structures, the multi-plate structure has higher resistance capacity to the impact from hypervelocity particles. Hence the multi-plate shield structure has a better shielding performance with a reduction in weight of the structure. It provides a promising alternative to the traditional shield in the spacecraft shield design.

Numerical investigation of the water entry of cylinders without and with spin

2017 ◽  
Vol 814 ◽  
pp. 131-164 ◽  
Author(s):  
Areti Kiara ◽  
Ruben Paredes ◽  
Dick K. P. Yue
Keyword(s):  
Contact Point ◽  
Qualitative Difference ◽  
Water Entry ◽  
Total Drag ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
Dynamic Components ◽  
Horizontal Cylinders ◽  
The Impact

We consider the water entry of horizontal cylinders with vertical impact velocity, either kept constant or freely falling, without and with spin, into quiescent water under the effect of gravity. We focus on the flow and cavity forming stages with non-dimensional submergence time$t$, Froude numbers$Fr$, spin ratios$\unicode[STIX]{x1D6FC}$and mass ratios$m$, all of$O(1)$. We develop numerical simulations using a modified smoothed particle hydrodynamics method to obtain predictions for the impact kinematics and dynamics. These are in detailed agreement with available experiments. We elucidate the evolutions of the free surface, contact point positions, flow field, forces and trajectories and their dependence on$Fr$,$\unicode[STIX]{x1D6FC}$and$m$. We define and quantify the contact point location$\unicode[STIX]{x1D703}(t)$as a function of$Fr$, clarifying the qualitative difference between sub- and supercritical$Fr$and the observed absence of air-entrained trailing cavities at low$Fr$. By subtracting the buoyancy associated with$\unicode[STIX]{x1D703}(t)$, we show that, unlike the total drag, the remaining dynamic components are qualitatively similar for all$Fr$. For a freely falling cylinder, we show that the total drag can be predicted from the constant velocity case with the same instantaneous velocity, providing a simple way to predict its trajectory based on the latter. The presence of spin results in lift, even when the asymmetry in$\unicode[STIX]{x1D703}$is small. For fixed$\unicode[STIX]{x1D6FC}$, lift increases with subcritical$Fr$. For a freely falling cylinder, the lateral motion causes an appreciable asymmetry in$\unicode[STIX]{x1D703}$and a reduction in lift.

scholarly journals Numerical Simulation of Non-Homogeneous Viscous Debris-Flows Based on the Smoothed Particle Hydrodynamics (SPH) Method

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2314 ◽  
Author(s):  
Shu Wang ◽  
Anping Shu ◽  
Matteo Rubinato ◽  
Mengyao Wang ◽  
Jiping Qin
Keyword(s):  
Debris Flow ◽  
Water Content ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle ◽  
The Impact ◽  
Kinetic And Potential Energies

Non-homogeneous viscous debris flows are characterized by high density, impact force and destructiveness, and the complexity of the materials they are made of. This has always made these flows challenging to simulate numerically, and to reproduce experimentally debris flow processes. In this study, the formation-movement process of non-homogeneous debris flow under three different soil configurations was simulated numerically by modifying the formulation of collision, friction, and yield stresses for the existing Smoothed Particle Hydrodynamics (SPH) method. The results obtained by applying this modification to the SPH model clearly demonstrated that the configuration where fine and coarse particles are fully mixed, with no specific layering, produces more fluctuations and instability of the debris flow. The kinetic and potential energies of the fluctuating particles calculated for each scenario have been shown to be affected by the water content by focusing on small local areas. Therefore, this study provides a better understanding and new insights regarding intermittent debris flows, and explains the impact of the water content on their formation and movement processes.

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