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Numerical simulation and experimental study of explosive projectile devices
Acta Astronautica 135 (2017) 56–62
Contents lists available at ScienceDirect
Acta Astronautica journal homepage: www.elsevier.com/locate/actaastro
Numerical simulation and experimental study of explosive projectile devices a
b,⁎
a
b
MARK
b
V.V. Selivanov , E.F. Gryaznov , N.A. Goldenko , A.D. Sudomoev , V.A. Feldstein a b
Bauman Moscow State Technical University (BMSTU), 105005 Moscow, Russian Federation Central Research Institute for Machine Building, 141070 Korolev, Russian Federation
A R T I C L E I N F O
A BS T RAC T
Keywords: Spacecraft Throwing explosive device High-speed impact Local blast Cumulative jet
A study of explosive-throwing device (ETD) was undertaken to simulate the hypervelocity impact of space debris fragments (SDF) and meteoroids with spacecrafts. The principle of operation of an ETD is based on the cumulative effect in combination with the cut-off head of the cumulative jet, which enables one to simulate a compact particle, such as a meteoroid or a fragment of space debris. Different design schemes of ETD with different composition explosive charge initiation schemes with notably low speeds of the jet cut-off are explored, and a method to control the particle velocity is proposed. Numerical simulation of device modes and basic technical characteristics of experimental testing are investigated.
1. Introduction During the experimental development of resistance spacecraft constructions to impact space debris fragments (SDFs), the main problem is to provide a compact particle acceleration in a given range of mass and velocity. Space debris consists predominantly of aluminum particles with velocities of 1–16 km/s. According to the models of OKM distribution, the main danger for the long-term orbital stations and spacecraft are SDFs with sizes up to 10 mm [1–4]. Those impactors can cause serious damage to the spacecraft elements and containments [5– 7]. When the ground-shock performance of the spacecraft and protective measures are applied, a two-stage light gas ballistic installation is commonly used, which provides a projectile speed range of 6–8 km/s, which is near the physical limit [8]. Increasing the speed is possible using blasting techniques in systems such as the cumulative system [9,10]. The main problem in this embodiment is the allocation of the cumulative jet compact warhead by a low-speed cut-off portion. This study examines the possibility of applying a cumulative scheme with the recess of "a hemisphere-cylinder" to throw the aluminum jets and a subsequent cut-off of the low-speed jet. Currently, the charge with a cumulative hollow cylinder hemisphere is investigated to throw high-speed compact steel elements in RFNC VNIIEF. In the BMSTU studies, compact cumulative facings were applied in the form of a truncated sphere or ellipsoid. 2. Statement of the problem ETD (Fig. 1) is a high-explosive (HE) charge, which is enclosed in
⁎
Corresponding author. E-mail address: [email protected] (N.A. Goldenko).
http://dx.doi.org/10.1016/j.actaastro.2017.01.042 Received 16 September 2016; Accepted 29 January 2017 Available online 31 January 2017 0094-5765/ © 2017 Published by Elsevier Ltd on behalf of IAA.
steel and a bimetal shaper to charge a hollow "hemisphere-cylinder". Initiation occurs in two manners: placing the detonation point at the center of the ring and knocking on the outer surface of the charge. Because the process of forming a cumulative jet compact particle search is complex, the ETD scheme was performed in conjunction with an experimental study of a numerical simulation of the process. The particle formation was modeled based on the equations of dynamics of a continuous medium in terms of Euler variables [11,12]. The material properties (equation of state and conditions of strength and fracture) were selected based on known experimental data [13]. The Euler field set includes the explosive and a body shaper with bimetallic recess "hemisphere-cylinder". The area consists of 720,000 cells with a size of 0,05 h 0,05 mm mesh. (See Fig. 1). On the outer surfaces of the Euler field conditions are free streaming, on the medium surface section are formulated conditions of kinematic and power contacts. The metal elements of the device is physically modeled based on the equation of state of Mi-Grüneisen. To describe the plastic flow model, Steinberg-Guiana is used, considering the change in shear modulus and yield stress during the deformation: For explosives, the equation of state is represented in JWL form. The software package ANSYS/AUTODYN was used for the calculation. 3. Effect of the ETD design parameters on the speed and nature of the projectile element We investigated the following ETD design parameters:
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
D. Thickness of the shaper. The thickness of the shaper must be sufficiently large to prevent the breakthrough products of the detonation from flying after the compact metatemym element. An increase in thickness reduces the throwing speed (Fig. 7). E. Radius cumulative recess in the shaper. According to the calculation results (Fig. 8), the radius of the best cumulative recesses is 0.136 of the explosive charge radius. F. Length of the cylindrical part of the recess in the cumulative shaper. The most stable formation of a compact propellant element in proximity radius cumulative recess and the length of its cylindrical part (Fig. 9).
Fig. 1. Calculation scheme: 1 – point detonation, 2 – ring detonation, 3 – shell, 4 – explosive, 5 – shaper.
Fig. 2. Effect of the driver material on the final throwing velocity and education gradientless site – particles.
Fig. 3. Operation of the shaper of different materials at t=13 ms: 1) 1100 AL-O; 2) 1100 AL-O; 3) AL 6061-T6; 4) AL 7039.
Case thickness. According to the calculation results (Fig. 10), the body thickness does not significantly affect the characteristics of the compact projectile element.
A. Shaper material (1100 AL-O, AL 6061-T6, AL 2024, AL 7039). The best alloy is AL 6061-T6 because the shaped-charge jet propelling element is more compact and has a more regular shape (see Figs. 2 and 3).
G. Thickness of the lining under the charge. To change the throwing speed of the charge generator, a gasket with material density less than the density of the explosives can be used, e.g., plexiglass. By increasing the thickness of the gasket by 1 mm, the particlethrowing speed is reduced to approximately 500 m/s (Fig. 11).
B. HE type. (El-506C, TNT, PBX-9404-03, HMX, C4). When the experimental developments El-506C and PBX-9404-03 are used: the El-506C speed to throw the element was 5–7 km/s. In the case of PBX-9404-03, the speed increased to 11 km/s (Fig. 4).
H. Overall dimensions of the ETD. Calculations with dimensions of charges: 25×30 mm, 50×60 mm, 75×90 mm, 100×120 mm, 200×240 mm and 400 h480 mm. When resizing, the throwing speed is practically constant. The size of the compact particle changes according to the change in charge size (Table 1).
C. Method to initiate the explosive charge (point detonation and ring detonation). Due to the convergence of a detonation wave to the charge symmetry axis when the ring detonation occurs pressurized Mach wave formation and its irregular reflection, it leads to increased throwing speed (Fig. 5). The pressure in front of the detonation wave for the point and ring initiations varies significantly (Fig. 6). 57
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 4. Effect of the explosive type on the final throwing velocity and education gradientless site – particles with a point charge initiation.
Fig. 5. Effect of the ring diameter to undermine the final throwing speed and formation of the jet gradientless site.
Fig. 6. Profile of a shock wave on the charge axis.
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Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 7. Effect of the thickness of the final shaper on the throwing velocity and education gradientless jet area – particles.
Fig. 8. Effect of the recess diameter shaper on the final throwing speed and formation of the jet gradientless site – particles.
Fig. 9. Effect of the cylindrical part of the recess length shaper on the final speed and the formation of the jet gradientless site – particles.
59
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 10. Effect of the body thickness on the final throwing velocity and education gradientless jet area – particles.
Fig. 11. Effect of thickness of a lining made of plexiglass on the final throwing speed and formation of jets gradientless site – particles.
When steel discs with a notch "hemisphere-cylinder" are used, a stable compact element is formed, and the low-speed part of the jet is slowed so that it does not reach the final obstacle. For aluminum alloys, a compact unit is formed, but aluminum is a plastic material, and the low speed of the jet is stretched during the flight. It is difficult to completely separate the jet from the compact element using only the plate with a calibration opening (Fig. 12). Changing the cylindrical part of the excavation material from aluminum to steel (Fig. 13) does not affect the formation of a compact element. The same aluminum compact unit is thrown, but the remainder of the disk is held by a steel plate. In the numerical simulation of the process (Fig. 14), a major compact element and a disk of small particulate material were formed. This material can be removed by placing a thin metal plate in front of the obstacle. The compact unit penetrates the plate, whereas the dust remains on the plate.
Table 1 Change in properties of a compact propellant element when the size of the explosive projectile device is changed. Overall charge dimensions Diameter Х Length (mm)
25×30
50×60
75×90
100×120
200×240
400×480
Velocity, km/s Diameter, mm Length, mm
5,42 0,7 1,55
5,38 1,5 2,12
5,43 2,1 5,33
5,40 2,8 6,6
5,43 5,6 12,4
5,43 11,2 25,6
4. Jet cut-off mechanism
5. Experimental testing results
The formation of a cumulative jet from the recess of "a hemispherecylinder" is as follows. From the "hemisphere", the original compact jet is formed, and the recess cylindrical part accelerates the jet. If the "cylinder" is too small, the gradientless portion of the jet is not formed; if the cylinder is too long, at the end of the jet, the velocity gradient image is compressed, which can destroy the compact element.
Fig. 15 shows a prototype of the explosive-throwing device. We obtained the following results: – The speed of the compact particles obtained by the developed ETD
60
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 12. Compact element formation for various materials. Material: 1 – steel, 2 – aluminum.
Fig. 15. Prototype of an explosive-throwing device.
velocity was 11,33 ± 0,89 km/s, which was measured with a contactless magnetic sensor. Fig. 16 shows the characteristic shape of craters when the ETD was exposed without the cut-off of the low-speed jet (Fig. 16a) and with the use of a bimetallic clipper (Fig. 16b). Fig. 16a shows that crater has asymmetrical edges and weakly pronounced deepening in center. The crater surface has a rough shape. This indirectly confirms the absence of a cut-off of the low speed jet. Fig. 16b shows that crater is a hemispherical, has smooth symmetrical output edges and smooth, almost mirror-like surface. At the same time the total damage radius is much larger than the crater radius. The total damage to the semi-infinite barrier surface characterized by smaller craters, indicating that the cut-off low speed jet with a bimetallic shaper is triggered.
6. Comparison of the calculation results and experimental data
Fig. 13. Scheme of the bimetallic shaper.
The performance of the cumulative particle accelerator with explosives was calculated for two modes of charge initiation: a dot and a ring in the software package ANSYS/AUTODYN. The average speed of the head of the jet when ETD was used to undermine the point and ring was 6.98 km/s and 10.85 km/s, respectively (see Fig. 16). Table 2 shows a comparison of the data obtained with these calculations and experimental testing (Fig. 17).
7. Conclusions
Fig. 14. Throwing a compact element in the presence of a steel lining.
The designed ETD enables the particles to form a compact size of 2.0–2.5 mm and accelerates them up to a speed of 7–11 km/s. The use of a bimetallic shaper produces an efficient low-speed cutoff piece of the aluminum jet. The created ETD enables one to test the spacecraft protection from the impacts of man-made debris and meteoroids at speeds of up to 11 km/s.
was 7,0–11,3 km/s; the particle diameter was 2.0–2.5 mm; the particle mass was 0.1 g; – For the ETD with a point to initiate the charge, the limiting particle velocity was 6,2 ± 0,18 km/s, which was measured with a contact sensor frame; – For the ETD with a ring to initiate the charge, the limiting particle
61
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 16. Typical form of barrier after exposure to the ETD. a – Without the cut-off portion of the low speed, a – With the use of a bimetallic shaper.
Table 2 Comparison of the calculated and experimental data. Calculation
Experiment
Point undermine
The average speed of the head of the jet – particles 6, 98 km/s
The particle velocity was 6,2 ± 0,18 km/s when measured with the sensor base framework 50 mm. The deviation of the experimental results from the calculation of 14%.
Ring undermine
The average speed of the head of the jet – particles of 10.85 km/s
The particle velocity was 11,33 ± 0,89 km/s in the measurement of electromagnetic induction sensor with a base of 100 mm. The biggest speed in the experiment amounted to 16.2 km/s. The deviation of the experimental results from the calculation amounted to no more than 5%.
Fig. 17. Velocity distribution in the jet at the ring and point detonation charge. [7] M.N. Smirnova, K.A. Kondrat’ev, Space debris fragments impact on multi-phase fluid filled containments, Acta Astronaut. 79 (2012) 12–19. [8] S.A. Poniaev, S.V. Bobashev, B.G. Zhukov, R.O. Kurakin, A.I. Sedov, S.N. Izotov, S.L. Kulakov, M.N. Smirnova, Small-size railgun of mm-size solid bodies for hypervelocity material testing, Acta Astronaut. 109 (2015) 162–165. [9] V.F. Minin, I.V. Minin, O.V. Minin, Hypervelocity fragment formation technology for ground-based laboratory tests, Acta Astronaut. 104 (2014) 77–83. [10] B.V. Rumyantsev, A.I. Mikhaylin, Jet-charge as an effective tool in the development of spacecraft shields testing against micrometeoroids and man-made debris, Acta Astronaut. 109 (2015) 166–171. [11] S.V. Fedorov, Y.M. Bajanova, S.V. Ladov, Numerical analysis of the formation of explosive high-speed compact elements: the use of the 2 compact cumulative linings in the form of a truncated sphere or ellipsoid, in: Proceedings of the Russian Academy of Missile and Artillery Sciences, vol. 2 (82), 2014, pp. 87–96. [12] L.P. Orlenko, The physics of the explosion and shock, Textbook for High Schools – M.: FIZMATLIT, 2006. [13] D.A. Chemezov, Description of library materials software package ANSYS AUTODYN, ISJ Theor. Appl. Sci. 8 (16) (2014) 4–23.
References [1] Consolidated Document NASA/Sleeve According to the Specifications and Standards for the Russian Segment of the ISS, SSP 50094, 1997. [2] V. Adushkin, S. Veniaminov, S. Kozlov, M. Silnikov, Orbital missions safety – a survey of kinetic hazards, Acta Astronaut. 126 (2016). http://dx.doi.org/10.1016/ j.actaastro.2015.12.053. [3] D.V. Panov, M.V. Silnikov, A.I. Mikhaylin, I.S. Rubzov, V.B. Nosikov, E.Yu Minenko, D.A. Murtazin, Large-scale shielding structures in low earth orbits, Acta Astronaut. 109 (2015) 153–161. [4] N.N. Smirnov, A.B. Kiselev, M.N. Smirnova, V.F. Nikitin, Space traffic hazards from orbital debris mitigation strategies, Acta Astronaut. 109 (2015) 144–152. http:// dx.doi.org/10.1016/j.actaastro.2014.09.014i. [5] N.N. Smirnov, K.A. Kondratyev, Evaluation of craters formation in hypervelocity impact of debris particles on solid structures, Acta Astronaut. 65 (11–12) (2009) 1796–1803. [6] N.N. Smirnov, A.B. Kiselev, K.A. Kondratyev, S.N. Zolkin, Impact of debris particles on space structures modeling, Acta Astronaut. 67 (2010) 333–343.
62
Contents lists available at ScienceDirect
Acta Astronautica journal homepage: www.elsevier.com/locate/actaastro
Numerical simulation and experimental study of explosive projectile devices a
b,⁎
a
b
MARK
b
V.V. Selivanov , E.F. Gryaznov , N.A. Goldenko , A.D. Sudomoev , V.A. Feldstein a b
Bauman Moscow State Technical University (BMSTU), 105005 Moscow, Russian Federation Central Research Institute for Machine Building, 141070 Korolev, Russian Federation
A R T I C L E I N F O
A BS T RAC T
Keywords: Spacecraft Throwing explosive device High-speed impact Local blast Cumulative jet
A study of explosive-throwing device (ETD) was undertaken to simulate the hypervelocity impact of space debris fragments (SDF) and meteoroids with spacecrafts. The principle of operation of an ETD is based on the cumulative effect in combination with the cut-off head of the cumulative jet, which enables one to simulate a compact particle, such as a meteoroid or a fragment of space debris. Different design schemes of ETD with different composition explosive charge initiation schemes with notably low speeds of the jet cut-off are explored, and a method to control the particle velocity is proposed. Numerical simulation of device modes and basic technical characteristics of experimental testing are investigated.
1. Introduction During the experimental development of resistance spacecraft constructions to impact space debris fragments (SDFs), the main problem is to provide a compact particle acceleration in a given range of mass and velocity. Space debris consists predominantly of aluminum particles with velocities of 1–16 km/s. According to the models of OKM distribution, the main danger for the long-term orbital stations and spacecraft are SDFs with sizes up to 10 mm [1–4]. Those impactors can cause serious damage to the spacecraft elements and containments [5– 7]. When the ground-shock performance of the spacecraft and protective measures are applied, a two-stage light gas ballistic installation is commonly used, which provides a projectile speed range of 6–8 km/s, which is near the physical limit [8]. Increasing the speed is possible using blasting techniques in systems such as the cumulative system [9,10]. The main problem in this embodiment is the allocation of the cumulative jet compact warhead by a low-speed cut-off portion. This study examines the possibility of applying a cumulative scheme with the recess of "a hemisphere-cylinder" to throw the aluminum jets and a subsequent cut-off of the low-speed jet. Currently, the charge with a cumulative hollow cylinder hemisphere is investigated to throw high-speed compact steel elements in RFNC VNIIEF. In the BMSTU studies, compact cumulative facings were applied in the form of a truncated sphere or ellipsoid. 2. Statement of the problem ETD (Fig. 1) is a high-explosive (HE) charge, which is enclosed in
⁎
Corresponding author. E-mail address: [email protected] (N.A. Goldenko).
http://dx.doi.org/10.1016/j.actaastro.2017.01.042 Received 16 September 2016; Accepted 29 January 2017 Available online 31 January 2017 0094-5765/ © 2017 Published by Elsevier Ltd on behalf of IAA.
steel and a bimetal shaper to charge a hollow "hemisphere-cylinder". Initiation occurs in two manners: placing the detonation point at the center of the ring and knocking on the outer surface of the charge. Because the process of forming a cumulative jet compact particle search is complex, the ETD scheme was performed in conjunction with an experimental study of a numerical simulation of the process. The particle formation was modeled based on the equations of dynamics of a continuous medium in terms of Euler variables [11,12]. The material properties (equation of state and conditions of strength and fracture) were selected based on known experimental data [13]. The Euler field set includes the explosive and a body shaper with bimetallic recess "hemisphere-cylinder". The area consists of 720,000 cells with a size of 0,05 h 0,05 mm mesh. (See Fig. 1). On the outer surfaces of the Euler field conditions are free streaming, on the medium surface section are formulated conditions of kinematic and power contacts. The metal elements of the device is physically modeled based on the equation of state of Mi-Grüneisen. To describe the plastic flow model, Steinberg-Guiana is used, considering the change in shear modulus and yield stress during the deformation: For explosives, the equation of state is represented in JWL form. The software package ANSYS/AUTODYN was used for the calculation. 3. Effect of the ETD design parameters on the speed and nature of the projectile element We investigated the following ETD design parameters:
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
D. Thickness of the shaper. The thickness of the shaper must be sufficiently large to prevent the breakthrough products of the detonation from flying after the compact metatemym element. An increase in thickness reduces the throwing speed (Fig. 7). E. Radius cumulative recess in the shaper. According to the calculation results (Fig. 8), the radius of the best cumulative recesses is 0.136 of the explosive charge radius. F. Length of the cylindrical part of the recess in the cumulative shaper. The most stable formation of a compact propellant element in proximity radius cumulative recess and the length of its cylindrical part (Fig. 9).
Fig. 1. Calculation scheme: 1 – point detonation, 2 – ring detonation, 3 – shell, 4 – explosive, 5 – shaper.
Fig. 2. Effect of the driver material on the final throwing velocity and education gradientless site – particles.
Fig. 3. Operation of the shaper of different materials at t=13 ms: 1) 1100 AL-O; 2) 1100 AL-O; 3) AL 6061-T6; 4) AL 7039.
Case thickness. According to the calculation results (Fig. 10), the body thickness does not significantly affect the characteristics of the compact projectile element.
A. Shaper material (1100 AL-O, AL 6061-T6, AL 2024, AL 7039). The best alloy is AL 6061-T6 because the shaped-charge jet propelling element is more compact and has a more regular shape (see Figs. 2 and 3).
G. Thickness of the lining under the charge. To change the throwing speed of the charge generator, a gasket with material density less than the density of the explosives can be used, e.g., plexiglass. By increasing the thickness of the gasket by 1 mm, the particlethrowing speed is reduced to approximately 500 m/s (Fig. 11).
B. HE type. (El-506C, TNT, PBX-9404-03, HMX, C4). When the experimental developments El-506C and PBX-9404-03 are used: the El-506C speed to throw the element was 5–7 km/s. In the case of PBX-9404-03, the speed increased to 11 km/s (Fig. 4).
H. Overall dimensions of the ETD. Calculations with dimensions of charges: 25×30 mm, 50×60 mm, 75×90 mm, 100×120 mm, 200×240 mm and 400 h480 mm. When resizing, the throwing speed is practically constant. The size of the compact particle changes according to the change in charge size (Table 1).
C. Method to initiate the explosive charge (point detonation and ring detonation). Due to the convergence of a detonation wave to the charge symmetry axis when the ring detonation occurs pressurized Mach wave formation and its irregular reflection, it leads to increased throwing speed (Fig. 5). The pressure in front of the detonation wave for the point and ring initiations varies significantly (Fig. 6). 57
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 4. Effect of the explosive type on the final throwing velocity and education gradientless site – particles with a point charge initiation.
Fig. 5. Effect of the ring diameter to undermine the final throwing speed and formation of the jet gradientless site.
Fig. 6. Profile of a shock wave on the charge axis.
58
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 7. Effect of the thickness of the final shaper on the throwing velocity and education gradientless jet area – particles.
Fig. 8. Effect of the recess diameter shaper on the final throwing speed and formation of the jet gradientless site – particles.
Fig. 9. Effect of the cylindrical part of the recess length shaper on the final speed and the formation of the jet gradientless site – particles.
59
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 10. Effect of the body thickness on the final throwing velocity and education gradientless jet area – particles.
Fig. 11. Effect of thickness of a lining made of plexiglass on the final throwing speed and formation of jets gradientless site – particles.
When steel discs with a notch "hemisphere-cylinder" are used, a stable compact element is formed, and the low-speed part of the jet is slowed so that it does not reach the final obstacle. For aluminum alloys, a compact unit is formed, but aluminum is a plastic material, and the low speed of the jet is stretched during the flight. It is difficult to completely separate the jet from the compact element using only the plate with a calibration opening (Fig. 12). Changing the cylindrical part of the excavation material from aluminum to steel (Fig. 13) does not affect the formation of a compact element. The same aluminum compact unit is thrown, but the remainder of the disk is held by a steel plate. In the numerical simulation of the process (Fig. 14), a major compact element and a disk of small particulate material were formed. This material can be removed by placing a thin metal plate in front of the obstacle. The compact unit penetrates the plate, whereas the dust remains on the plate.
Table 1 Change in properties of a compact propellant element when the size of the explosive projectile device is changed. Overall charge dimensions Diameter Х Length (mm)
25×30
50×60
75×90
100×120
200×240
400×480
Velocity, km/s Diameter, mm Length, mm
5,42 0,7 1,55
5,38 1,5 2,12
5,43 2,1 5,33
5,40 2,8 6,6
5,43 5,6 12,4
5,43 11,2 25,6
4. Jet cut-off mechanism
5. Experimental testing results
The formation of a cumulative jet from the recess of "a hemispherecylinder" is as follows. From the "hemisphere", the original compact jet is formed, and the recess cylindrical part accelerates the jet. If the "cylinder" is too small, the gradientless portion of the jet is not formed; if the cylinder is too long, at the end of the jet, the velocity gradient image is compressed, which can destroy the compact element.
Fig. 15 shows a prototype of the explosive-throwing device. We obtained the following results: – The speed of the compact particles obtained by the developed ETD
60
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 12. Compact element formation for various materials. Material: 1 – steel, 2 – aluminum.
Fig. 15. Prototype of an explosive-throwing device.
velocity was 11,33 ± 0,89 km/s, which was measured with a contactless magnetic sensor. Fig. 16 shows the characteristic shape of craters when the ETD was exposed without the cut-off of the low-speed jet (Fig. 16a) and with the use of a bimetallic clipper (Fig. 16b). Fig. 16a shows that crater has asymmetrical edges and weakly pronounced deepening in center. The crater surface has a rough shape. This indirectly confirms the absence of a cut-off of the low speed jet. Fig. 16b shows that crater is a hemispherical, has smooth symmetrical output edges and smooth, almost mirror-like surface. At the same time the total damage radius is much larger than the crater radius. The total damage to the semi-infinite barrier surface characterized by smaller craters, indicating that the cut-off low speed jet with a bimetallic shaper is triggered.
6. Comparison of the calculation results and experimental data
Fig. 13. Scheme of the bimetallic shaper.
The performance of the cumulative particle accelerator with explosives was calculated for two modes of charge initiation: a dot and a ring in the software package ANSYS/AUTODYN. The average speed of the head of the jet when ETD was used to undermine the point and ring was 6.98 km/s and 10.85 km/s, respectively (see Fig. 16). Table 2 shows a comparison of the data obtained with these calculations and experimental testing (Fig. 17).
7. Conclusions
Fig. 14. Throwing a compact element in the presence of a steel lining.
The designed ETD enables the particles to form a compact size of 2.0–2.5 mm and accelerates them up to a speed of 7–11 km/s. The use of a bimetallic shaper produces an efficient low-speed cutoff piece of the aluminum jet. The created ETD enables one to test the spacecraft protection from the impacts of man-made debris and meteoroids at speeds of up to 11 km/s.
was 7,0–11,3 km/s; the particle diameter was 2.0–2.5 mm; the particle mass was 0.1 g; – For the ETD with a point to initiate the charge, the limiting particle velocity was 6,2 ± 0,18 km/s, which was measured with a contact sensor frame; – For the ETD with a ring to initiate the charge, the limiting particle
61
Acta Astronautica 135 (2017) 56–62
V.V. Selivanov et al.
Fig. 16. Typical form of barrier after exposure to the ETD. a – Without the cut-off portion of the low speed, a – With the use of a bimetallic shaper.
Table 2 Comparison of the calculated and experimental data. Calculation
Experiment
Point undermine
The average speed of the head of the jet – particles 6, 98 km/s
The particle velocity was 6,2 ± 0,18 km/s when measured with the sensor base framework 50 mm. The deviation of the experimental results from the calculation of 14%.
Ring undermine
The average speed of the head of the jet – particles of 10.85 km/s
The particle velocity was 11,33 ± 0,89 km/s in the measurement of electromagnetic induction sensor with a base of 100 mm. The biggest speed in the experiment amounted to 16.2 km/s. The deviation of the experimental results from the calculation amounted to no more than 5%.
Fig. 17. Velocity distribution in the jet at the ring and point detonation charge. [7] M.N. Smirnova, K.A. Kondrat’ev, Space debris fragments impact on multi-phase fluid filled containments, Acta Astronaut. 79 (2012) 12–19. [8] S.A. Poniaev, S.V. Bobashev, B.G. Zhukov, R.O. Kurakin, A.I. Sedov, S.N. Izotov, S.L. Kulakov, M.N. Smirnova, Small-size railgun of mm-size solid bodies for hypervelocity material testing, Acta Astronaut. 109 (2015) 162–165. [9] V.F. Minin, I.V. Minin, O.V. Minin, Hypervelocity fragment formation technology for ground-based laboratory tests, Acta Astronaut. 104 (2014) 77–83. [10] B.V. Rumyantsev, A.I. Mikhaylin, Jet-charge as an effective tool in the development of spacecraft shields testing against micrometeoroids and man-made debris, Acta Astronaut. 109 (2015) 166–171. [11] S.V. Fedorov, Y.M. Bajanova, S.V. Ladov, Numerical analysis of the formation of explosive high-speed compact elements: the use of the 2 compact cumulative linings in the form of a truncated sphere or ellipsoid, in: Proceedings of the Russian Academy of Missile and Artillery Sciences, vol. 2 (82), 2014, pp. 87–96. [12] L.P. Orlenko, The physics of the explosion and shock, Textbook for High Schools – M.: FIZMATLIT, 2006. [13] D.A. Chemezov, Description of library materials software package ANSYS AUTODYN, ISJ Theor. Appl. Sci. 8 (16) (2014) 4–23.
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