The hottest penetration target based on ansyslsdyn

2022-08-23
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Numerical simulation of shaped charge jet penetrating target plate based on ANSYS/ls.dyna

linear shaped charge (LSC) is also known as half face symmetrical shaped charge, which is shaped like a wedge. After the explosion of the explosive, the high turbulence and high pressure detonation products spread rapidly to the normal direction of the surface of the cavity. Due to the hole, the products gather to the axis and form a high-speed and high-pressure air flow, which acts on the reduction cover with a pressure of up to hundreds of thousands of atmospheres and collapses it. The plane moves backward towards the axis of symmetry, and a high-speed collision occurs on the axis of symmetry. The metal near the inner wall of the reduction cover extrudes a sheet metal jet on the symmetrical half plane moving towards the bottom of the installation at a high speed. When the jet interacts with the target, it forces the pressure on the surface of the target to suddenly reach millions of atmospheres. Under the action of high pressure, the media on the surface of the target plate is displaced and stacked to the side area. Linear shaped charge is based on this kind of flaky "shaped knife" to realize the cutting of target plate. Through the mutual verification and guidance of numerical simulation and experiment, the linear shaped charge cutter is studied to cut the target plate, and the cutter model is reasonably established, which is numerically simulated by ANSYS/ls.dyna3d software

1 theoretical analysis and experimental research

according to the steady theory of Birkhoff et al., when the detonation wave strikes the wedge-shaped reduction cover, it is assumed that the pressure on the whole cover wall is equal everywhere, and it is compressed inward at a small speed K. Since the detonation wave takes a certain time from the top of the cover to the surface of the cover, the included angle 2 between the moving cover walls is greater than the original top angle 2 α。 Figure L shows the geometry of the pressing process. The wedge-shaped shroud is symmetrical, so α Represents half of the wedge apex angle, β Indicates the pressing angle

after pushing to the calculation, it can be seen that ∠ app 'in the semicolon l of the carbamide speed K of the approximate cover, the pressed cover wall moves inward from both sides of the wedge, and the collision point V1 on both sides moves from a to B. Applying the sine theorem, it is concluded that:

Birkhoff et al. Can predict the speed and mass of the steady-state jet and pestle formed by the wedge-shaped reducing cover with water

in the test, the assembly method as shown in Figure 2 is adopted, and the top angle of the cover is 70 °. The shape reducing cover and shell are made of lead antimony alloy, and the target plate is made of 5A06 aluminum alloy. The detonation mode is simultaneous detonation on the edge

three tests were carried out on the cutter with a top angle of 70 °, and the penetration depths were 6.15mm, 6.02 mm and 6.23mm respectively. The average penetration depth of the three tests was 6.133mm

2 numerical simulation and simulation results

the linear shaped energy cutter with the same materials and parameters as the above test is used as the model. The dredging model has the characteristics of small volume and good cutting effect. Its structural dimensions are shown in Figure 3. Unit: mm

the materials and parameters in the numerical simulation are the same as those in the above tests. Due to the symmetrical parts of the structure, 1/2 longitudinal section structure is used for modeling. Assuming that the initiation mode is simultaneous initiation on the edge, in the calculation, multiple initiation points are set, and these points detonate at the same time, so as to achieve the purpose of simultaneous initiation on the edge. Considering the actual situation, the zero explosion height is adopted between the linear cutter and the target plate

according to the simulation results, the penetration depth is 6.72 mm, while the cutting depth of the above test is 6.133 mm, with a difference of 8.74%. Through comparison, the reliability and correctness of the simulation are proved. The above errors may be due to the selection of parameters and state equations, the initiation mode of multi-point initiation instead of line initiation, lattice division and so on

3 analysis of simulation results

when the explosive is detonated, the detonation wave propagates rapidly along the longitudinal and transverse directions at the same time, causing pressure on the liner and shell, and crushing the liner. Under the action of detonation wave, the liner accelerates and collides on the symmetrical armor surface, forming a high-speed metal jet and a relatively low velocity pestle. As the liner continues to collapse, the jet mass and energy continue to flow in, and the jet head continues to accelerate to the maximum. Due to the different velocities of the pestle and the jet head, the jet gradually stretches and breaks in the process of movement. Then, as the inflow of jet mass and energy decreases, the velocity of jet head decreases gradually

in this example, the physical images of the formation of the shaped jet and the penetration of the target plate at different times are shown in Figure 4, and the longitudinal velocity changes of different nodes are shown in Figure 5

in Figure 4, a is the initial time when the linear shaped charge cutter penetrates the target plate, and zero explosion height is adopted. B is explosive explosion L μ After s, the jet is about to be generated, but it is blocked by the target plate. At this time, the velocity of the jet head is the maximum. C is 2.6 after initiation μ S state, because the velocity of the jet head is greater than the velocity of the pestle, the jet is gradually stretched and cut off. D is the final state of penetration. Due to the reduction of energy and jet mass, the velocity of jet head decreases to the same as that of pestle. When the energy is lower than a certain value, the penetration ends

in Figure 5, a is the node of the jet head, with the maximum speed, reaching 4000m, and the body temperature will certainly continue to rise above/s. B is the middle and rear node of the jet, and the speed is small, only more than 1500m/s. C refers to the accumulation of the jet that has lost penetration ability at the bottom of the perforation, causing agitation. When the jet head is at 1 female, the velocity reaches the maximum and decreases rapidly, at 1.5 μ The speed decreases to about 1000 MLS

4 conclusion

the wood simulation adopts the ignition mode of zero explosion height and simultaneous initiation on the edge. Through the numerical simulation of the linear shaped charge cutter penetrating the target plate, the following conclusions are drawn: the concept of environmental protection is deeply rooted in the hearts of the people

1) computer simulation technology plays an increasingly important role in the development, testing and evaluation of weapon systems, which show a high level of tear resistance, The premise of numerical simulation is to establish the zigzag experiment, which is mainly used to determine the simulation model of the limit accuracy of zigzag strength of materials or components. In the process of LS-DYNA numerical simulation, the parameters are selected correctly, and the results can correctly reflect the formation of linear shaped charge cutter jet and the process of penetrating the target plate, which is consistent with the test results

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