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1

Effect of an eccentric decoupled charge on rock mass blasting

Kim Jung-Gyu, Ali Mahrous A.M., Kim Jong-Gwan

Journal of Sustainable Mining

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2020

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Vol. 19, iss. 1

1--10

EN

Experimental and numerical analyses were conducted to investigate the effect of an eccentric loaded contour hole on a rock mass. In the concrete blocks used for the analyses, detonating cords were placed at the centre of the blast hole and eccentrically against the wall of the blast hole. PFC2D and AUTODYN were used for the numerical analyses, and the results of these software showed that an eccentric decoupled charge can result in the directional development of fractures, thereby enabling the control of cracks in the opposite direction. Even though both types of blasting have identical decoupling indexes, the crack and fracture patterns were affected by the location of the explosive, tamping, and other conditions. The results showed that an eccentric charge holder can be applicable to control the fracture direction and the damaged zone. For an eccentric charge, the initial crack was generated at 0.01 ms and expanded in the intended direction. For the eccentric charge, the maximum pressure at the area in contact with the blast hole wall exceeded that for the central decoupled charge by a factor of 5.5. Furthermore, the pressure in the intended direction was twice of that in the opposite direction.

2

Experimental research and numerical analysis of 9 mm Parabellum projectile penetration of ultra-high molecular weight polyethylene layers

Wiśniewski A., Pacek D.

Problemy Techniki Uzbrojenia

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2013

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R. 42, z. 127

55--64

EN

The paper presents results of experimental research and numerical analysis of the 9 mm Parabellum projectile (brass jacket, lead core) impact (impact velocity Vi = 365 m/s) into layers of the nonwoven polyethylene Dyneema®SB71 (100x100 mm) placed on the backing material. 3D numerical simulations with the use of the Ansys Autodyn v14 program were made. On the basis of the literature and own results of the weight drop test into ballistic plasticine (backface signature BFS = 18-24 mm) conforming to experimental tests numerical model of backing material was made. As a boundary condition in the numerical simulations of projectile impact into Dyneema®SB71 layers it was assumed loading of the tightening belt with 25 N force. In difference to experimental results in numerical simulations the front part of the jacket torn off and the core material flow outside the jacket and there were no perforated layers.

PL

W artykule przedstawiono wyniki badań ostrzałem oraz analiz numerycznych uderzenia pocisku 9 mm Parabellum (płaszcz mosiężny, rdzeń. ołowiany, prędkość uderzenia Vi = 365 m/s) w warstwy nietkanego wyrobu polietylenowego Dyneema®SB71 (100x100 mm) umieszczonego na podłożu balistycznym. Symulacje numeryczne 3D zrealizowano w programie do analiz dynamicznych Ansys Autodyn v14. W oparciu o dane literaturowe oraz własne wyniki zrzutu swobodnego ciężarka na plastelinę balistyczną (głębokość deformacji podłoża BFS = 18-24 mm) opracowano zgodny z wynikami badań eksperymentalnych model numeryczny podłoża balistycznego. Jako warunek brzegowy w symulacji uderzenia pocisku w warstwy Dyneema'y®SB71 przyjęto obciążenie paska dociskającego siłą 25 N. W odróżnieniu od badań ostrzałem w symulacji numerycznej oderwała się przednia część płaszcza pocisku oraz nie nastąpiło przebicie żadnej z warstw wyrobu polietylenowego Dyneema®SB71.

3

Add-on passive armour for light armoured vehicles protection

Wiśniewski A., Żochowski P.

Problemy Techniki Uzbrojenia

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2013

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R. 42, z. 125

17--24

EN

The possibility of increasing of passive armour protection effectiveness by inclination of its surface in relation to the initial axis of the projectile trajectory was analyzed in this article. Phenomena which occur during penetration of the armour-piercing projectiles API into steel plates placed at different angles in relation to the initial axis of the projectile were described. Characteristic mechanisms of the API projectile behaviour observed during experiments, i.e. fragmentation of the projectile core during oblique perforation and deflecting of its trajectory from the initial axis of the penetration, were reproduced in the Ansys Autodyn v.14 computer program. On the basis of numerical analyses and results of experimental tests available in literature the layer of the armour was designer which contains perforated steel plates placed at the angle α=45º in relation to predicted projectile trajectory. Computer simulations of the 14.5 mm AP type B-32 projectile impact onto the model of the armour layer were made in the Ansys Autodyn v.14 program. The results obtained during the numerical analyses confirm that perforated steel plates placed at proper angle have high protection effectiveness against the API projectiles of the 4th level of STANAG 4569.

PL

W artykule przeanalizowano możliwość zwiększenia skuteczności ochronnej pancerza pasywnego w wyniku pochylenia jego powierzchni względem początkowej osi trajektorii lotu pocisku. Dokonano analizy zjawisk zachodzących podczas penetracji pocisków przeciwpancernych API (armour-piercing) w płyty stalowe umieszczone pod różnymi kątami. Zaobserwowane podczas badań eksperymentalnych charakterystyczne mechanizmy powstrzymywania pocisków API (kruszenie rdzenia pocisku przy perforacji kątowej, odchylanie jego toru lotu od początkowej osi penetracji) odwzorowano numerycznie w programie Ansys Autodyn v. 14. Następnie, na podstawie analiz numerycznych oraz dostępnych w literaturze wyników eksperymentalnych, zaprojektowano warstwę pancerza, wykorzystującą perforowane blachy stalowe umieszczone pod kątem 45º w stosunku do przewidywanego toru lotu pocisku. W programie Ansys Autodyn v. 14 wykonano symulacje komputerowe uderzenia 14,5 mm pocisku API typu B-32 w zaprojektowaną warstwę pancerza. Uzyskane podczas analiz numerycznych wyniki mogą świadczyć o tym, że stalowe płyty perforowane umieszczone pod odpowiednim kątem względem uderzającego pocisku, mają wysoką skuteczność ochronną przeciw pociskom AP na poziomie 4 wg STANAG 4569.

4

Experimental research and numerical analysis of penetration of the twaron T750 aramid fabric with the 9 mm Parabellum projectile

Wiśniewski A., Pacek D.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2013

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Vol. 4, Nr 3 (13)

7-22

EN

The paper presents results of experimental research and numerical analysis of the penetration process of the Twaron T750 aramid fabric with the 9 mm Parabellum projectile (brass jacket, lead core). Numerical simulations of the 9 mm Parabellum projectile impact into 10 and 16 layers of the Twaron T750 fabric with the use of the Ansys Autodyn v13 program for dynamic analyses were conducted on the basis of 3-dimensional solid numerical models. As a boundary condition in the experiment and in the numerical simulations it was assumed that all the four edges of the fabric were fixed. In the numerical simulations the sample of 50 ×50 mm dimensions and the impact velocities Vi = 448 m/s for 16 layers of the Twaron T750 fabric and Vi = 454 m/s for 10 layers of Twaron T750 fabric were adopted. In the paper the results of the numerical simulations for three material configurations with the same friction coefficients and for different values of yarn-yarn friction in case of one material configuration are presented. Residual velocity of the penetrator for the highest friction coefficient μs = 1 decreased of 13.1% in comparison to simulation with no friction (μs = 0).

5

Numerical investigation of a movable wall response on a flame propagation

Górniak A., Kaźmierczak A.

Journal of KONES

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2013

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Vol. 20, No. 2

135--141

EN

This paper contains a description of a shock wave (called a flame when the deflagration is considered) propagation pattern impact on a motion of a barrier. Here, the numerical research was conducted on a model of a pyrotechnic actuator, hence, the piston is understood as a movable barrier. The processes occurring within the pyrotechnic actuators after ignition of a pyrotechnic propellants have been explained. The investigations are focused on the dependence of a shape of the actuator’s combustion chamber and the piston stroke time. It appears that the appropriate design of the combustion chamber can decrease the time required for a piston total stroke using this same type of a propellant. The visualization of the flame occurring due to ignition of the propellant is crucial for understanding the dependence between the construction of the actuators interior and the piston stroke time. Therefore, the approach of simulating numerically the flames aroused. The simulation was conducted on a full scale 3D model of a pyrotechnic actuator which is a detail representation of a real object on which the verification test will be conducted. However, only the flame propagation was considered here. The material of an actuators members was not investigated, hence the AUTODYN solver considered them as a single rigid bodies with its own mass and inertia.

6

The numerical simulation of the pyrotechnic actuator for the active bumper

Górniak A., Kaźmierczak A., Krakowian K., Włostowski R, Błasiński T.

Journal of KONES

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2012

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Vol. 19, No. 3

141-147

EN

The paper contains the description and classification of pyrotechnic actuators focusing on the automotive industry applications. This paper also explains the compatibility issues during frontal impact of a passenger car with a large truck. The construction of the pyrotechnic actuators for the "active bumper" is presented here. The processes occurring within the pyrotechnic actuators after ignition of a pyrotechnic propellants have been explained. The investigations are focused on the dependence of a shape of the actuator's combustion chamber and the piston stroke time. It appears that the appropriate design of the combustion chamber can decrease the time required for a piston stroke using this same type of a propellant. This also allows to reduce the amount of propellant when the more rapid stroke is not required. This is because of the characteristics of the detonation waves which are responsible for the piston movement. The visualization of the detonation waves occurring due to ignition of the propellant is crucial for understanding the dependence between the construction of the actuators interior and the piston stroke time. Therefore, the approach of simulating numerically the detonation waves aroused. This simulation was conducted with aid of ANSYS Workbench 13 environment using the AUTODYN module. The numerical tests consists on modelling the actuator without changing the overall dimensions as well as the parameters of the propellant. The only elements modified were piston and the bottom of the cylinder shape.

7

Simulation of Steel Armour Penetration Using the Johnson-Cook Model

Wiśniewski A., Tomaszewski Ł.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2011

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Vol. 2, Nr 4 (6)

27-36

EN

The numerical simulations were carried out of penetration of 12.7 mm armour piercing projectile into the ARMOX 500 steel armour with the use of the AUTODYN 2D software program applying axis symmetry. The calculations were performed by means of the SPH (Smooth Particle Hydrodynamic) method. A constitutive Johnson-Cook model was used for both the armour and the projectile. The influence of discretization density of the numerical model on the residual velocity vr of the projectile, its wear and time of calculations was studied. An eight times decrease in the distance between the SPH particles in the numerical model causes an over 130 fold increase of the projectile residual velocity and a 960 fold increase in the calculation time. The examined aspects included the influence of armour thickness g and yield stress Re of the projectile material on its residual velocity and manner of the projectile and armour damage. The residual velocity of the projectile decreases together with an increase of the armour thickness and for g = 20 mm is vr = 300 m/s. Together with a decrease of the yield stress of the projectile material its residual velocity also decreases, the wear of the projectile increases, the shape and the dimensions of cross section hole in the armour also change.

8

Numerical Simulations of Penetration of 9 mm Parabellum Bullet into Kevlar Layers : Erosion Selection in Autodyn Program

Wiśniewski A., Pacek D.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2011

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Vol. 2, Nr 3 (5)

11-20

EN

A numerical model was performed of penetration of 9 mm Parabellum bullet into Kevlar layers, with the use of the AUTODYN software program. Simulations were conducted with a bullet modelled by means of the Smooth Particle Hydrodynamicsmethod (SPH) and with an armour coded by a Lagrange grid. The simulations were performed for 20 layers of Kevlar (one layer: thickness - 0.3 mm, surface density - 220 g/cm²) and for impact velocity of 350 m/s. The comparison included the mean velocity of the bullet (which takes into account the velocities of particles that separated from the part of the bullet penetrating the armour) and the velocities at gauge points established near the axis of symmetry of the bullet. The gauge point representative for velocity of the bullet was indicated. With regard to excessively large deformations of the grid, that caused interruption of the initial simulation, the criteria of erosion (cells removal) were introduced. From effective strains available in the AUTODYN software, the effective instantaneous geometric strain was selected. Influence of the erosion strain (value of strain for which cells are removed) onto the mass of removed cells and the residual velocity of the bullet were investigated. Simulations with neglect and respect to mass of removed cells in further calculations were performed. The erosion criteria for which further simulations should be conducted were indicated.